#3628 Add support for locale parameter for numberFormat and dateFormat

core/src/main/java/org/mapstruct/IterableMapping.java

@@ -66,19 +66,38 @@ public @interface IterableMapping {
     /**
      * A format string as processable by {@link SimpleDateFormat} if the annotated method maps from an iterable of
      * {@code String} to an iterable {@link Date} or vice-versa. Will be ignored for all other element types.
+     * <p>
+     * If the {@link #locale()} is also specified, the format will consider the specified locale when processing
+     * the date. Otherwise, the system's default locale will be used.
      *
      * @return A date format string as processable by {@link SimpleDateFormat}.
+     * @see #locale()
      */
     String dateFormat() default "";
 
     /**
      * A format string as processable by {@link DecimalFormat} if the annotated method maps from a
      *  {@link Number} to a {@link String} or vice-versa. Will be ignored for all other element types.
+     * <p>
+     * If the {@link #locale()} is also specified, the number format will be applied in the context of the given locale.
+     * Otherwise, the system's default locale will be used to process the number format.
      *
      * @return A decimal format string as processable by {@link DecimalFormat}.
+     * @see #locale()
      */
     String numberFormat() default "";
 
+    /**
+     * Specifies the locale to be used when processing {@link #dateFormat()} or {@link #numberFormat()}.
+     * <p>
+     * The locale should be a plain tag representing the language, such as "en" for English, "de" for German, etc.
+     * <p>
+     * If no locale is specified, the system's default locale will be used.
+     *
+     * @return A string representing the locale to be used when formatting dates or numbers.
+     */
+    String locale() default "";
+
     /**
      * A qualifier can be specified to aid the selection process of a suitable mapper. This is useful in case multiple
      * mappers (hand written of internal) qualify and result in an 'Ambiguous mapping methods found' error.

core/src/main/java/org/mapstruct/MapMapping.java

@@ -56,8 +56,12 @@ public @interface MapMapping {
     /**
      * A format string as processable by {@link SimpleDateFormat} if the annotated method maps from a map with key type
      * {@code String} to an map with key type {@link Date} or vice-versa. Will be ignored for all other key types.
+     * <p>
+     * If the {@link #locale()} is specified, the format will consider the specified locale when processing the date.
+     * Otherwise, the system's default locale will be used.
      *
      * @return A date format string as processable by {@link SimpleDateFormat}.
+     * @see #locale()
      */
     String keyDateFormat() default "";
 
@@ -65,27 +69,50 @@ public @interface MapMapping {
      * A format string as processable by {@link SimpleDateFormat} if the annotated method maps from a map with value
      * type {@code String} to an map with value type {@link Date} or vice-versa. Will be ignored for all other value
      * types.
+     * <p>
+     * If the {@link #locale()} is specified, the format will consider the specified locale when processing the date.
+     * Otherwise, the system's default locale will be used.
      *
      * @return A date format string as processable by {@link SimpleDateFormat}.
+     * @see #locale()
      */
     String valueDateFormat() default "";
 
     /**
      * A format string as processable by {@link DecimalFormat} if the annotated method maps from a
      *  {@link Number} to a {@link String} or vice-versa. Will be ignored for all other key types.
+     * <p>
+     * If the {@link #locale()} is specified, the number format will be applied in the context of the given locale.
+     * Otherwise, the system's default locale will be used.
      *
      * @return A decimal format string as processable by {@link DecimalFormat}.
+     * @see #locale()
      */
     String keyNumberFormat() default "";
 
     /**
      * A format string as processable by {@link DecimalFormat} if the annotated method maps from a
      *  {@link Number} to a {@link String} or vice-versa. Will be ignored for all other value types.
+     * <p>
+     * If the {@link #locale()} is specified, the number format will be applied in the context of the given locale.
+     * Otherwise, the system's default locale will be used.
      *
      * @return A decimal format string as processable by {@link DecimalFormat}.
+     * @see #locale()
      */
     String valueNumberFormat() default "";
 
+    /**
+     * Specifies the locale to be used when processing {@link SimpleDateFormat} or {@link DecimalFormat} for key or
+     * value mappings in maps. The locale should be a plain tag representing the language, such as "en" for English,
+     * "de" for German, etc.
+     * <p>
+     * If no locale is specified, the system's default locale will be used.
+     *
+     * @return A string representing the locale to be used when formatting dates or numbers in maps.
+     */
+    String locale() default "";
+
     /**
      * A key value qualifier can be specified to aid the selection process of a suitable mapper. This is useful in
      * case multiple mappers (hand written of internal) qualify and result in an 'Ambiguous mapping methods found'

core/src/main/java/org/mapstruct/Mapping.java

@@ -175,19 +175,38 @@ public @interface Mapping {
     /**
      * A format string as processable by {@link SimpleDateFormat} if the attribute is mapped from {@code String} to
      * {@link Date} or vice-versa. Will be ignored for all other attribute types and when mapping enum constants.
+     * <p>
+     * If the {@link #locale()} is also specified, the format will consider the specified locale when processing
+     * the date. Otherwise, the system's default locale will be used.
      *
      * @return A date format string as processable by {@link SimpleDateFormat}.
+     * @see #locale()
      */
     String dateFormat() default "";
 
     /**
      * A format string as processable by {@link DecimalFormat} if the annotated method maps from a
      *  {@link Number} to a {@link String} or vice-versa. Will be ignored for all other element types.
+     * <p>
+     * If the {@link #locale()} is also specified, the number format will be applied in the context of the given locale.
+     * Otherwise, the system's default locale will be used to process the number format.
      *
      * @return A decimal format string as processable by {@link DecimalFormat}.
+     * @see #locale()
      */
     String numberFormat() default "";
 
+    /**
+     * Specifies the locale to be used when processing {@link #dateFormat()} or {@link #numberFormat()}.
+     * <p>
+     * The locale should be a plain tag representing the language, such as "en" for English, "de" for German, etc.
+     * <p>
+     * If no locale is specified, the system's default locale will be used.
+     *
+     * @return A string representing the locale to be used when formatting dates or numbers.
+     */
+    String locale() default "";
+
     /**
      * A constant {@link String} based on which the specified target property is to be set.
      * <p>

processor/src/main/java/org/mapstruct/ap/internal/conversion/BigDecimalToStringConversion.java

@@ -14,8 +14,9 @@ import org.mapstruct.ap.internal.model.HelperMethod;
 import org.mapstruct.ap.internal.model.common.ConversionContext;
 import org.mapstruct.ap.internal.model.common.Type;
 
-import static org.mapstruct.ap.internal.util.Collections.asSet;
 import static org.mapstruct.ap.internal.conversion.ConversionUtils.bigDecimal;
+import static org.mapstruct.ap.internal.conversion.ConversionUtils.locale;
+import static org.mapstruct.ap.internal.util.Collections.asSet;
 
 /**
  * Conversion between {@link BigDecimal} and {@link String}.
@@ -64,18 +65,31 @@ public class BigDecimalToStringConversion extends AbstractNumberToStringConversi
     public List<HelperMethod> getRequiredHelperMethods(ConversionContext conversionContext) {
         List<HelperMethod> helpers = new ArrayList<>();
         if ( conversionContext.getNumberFormat() != null ) {
-            helpers.add( new CreateDecimalFormat( conversionContext.getTypeFactory() ) );
+            helpers.add( new CreateDecimalFormat(
+                conversionContext.getTypeFactory(),
+                conversionContext.getLocale() != null
+            ) );
         }
         return helpers;
     }
 
     private void appendDecimalFormatter(StringBuilder sb, ConversionContext conversionContext) {
-        sb.append( "createDecimalFormat( " );
+        boolean withLocale = conversionContext.getLocale() != null;
+        sb.append( "createDecimalFormat" );
+        if ( withLocale ) {
+            sb.append( "WithLocale" );
+        }
+        sb.append( "( " );
         if ( conversionContext.getNumberFormat() != null ) {
             sb.append( "\"" );
             sb.append( conversionContext.getNumberFormat() );
             sb.append( "\"" );
         }
+        if ( withLocale ) {
+            sb.append( ", " ).append( locale( conversionContext ) ).append( ".forLanguageTag( \"" );
+            sb.append( conversionContext.getLocale() );
+            sb.append( "\" )" );
+        }
 
         sb.append( " )" );
     }

processor/src/main/java/org/mapstruct/ap/internal/conversion/BigIntegerToStringConversion.java

@@ -15,9 +15,10 @@ import org.mapstruct.ap.internal.model.HelperMethod;
 import org.mapstruct.ap.internal.model.common.ConversionContext;
 import org.mapstruct.ap.internal.model.common.Type;
 
-import static org.mapstruct.ap.internal.util.Collections.asSet;
+import static org.mapstruct.ap.internal.conversion.ConversionUtils.locale;
 import static org.mapstruct.ap.internal.conversion.ConversionUtils.bigDecimal;
 import static org.mapstruct.ap.internal.conversion.ConversionUtils.bigInteger;
+import static org.mapstruct.ap.internal.util.Collections.asSet;
 
 /**
  * Conversion between {@link BigInteger} and {@link String}.
@@ -72,18 +73,31 @@ public class BigIntegerToStringConversion extends AbstractNumberToStringConversi
     public List<HelperMethod> getRequiredHelperMethods(ConversionContext conversionContext) {
         List<HelperMethod> helpers = new ArrayList<>();
         if ( conversionContext.getNumberFormat() != null ) {
-            helpers.add( new CreateDecimalFormat( conversionContext.getTypeFactory() ) );
+            helpers.add( new CreateDecimalFormat(
+                conversionContext.getTypeFactory(),
+                conversionContext.getLocale() != null
+            ) );
         }
         return helpers;
     }
 
     private void appendDecimalFormatter(StringBuilder sb, ConversionContext conversionContext) {
-        sb.append( "createDecimalFormat( " );
+        boolean withLocale = conversionContext.getLocale() != null;
+        sb.append( "createDecimalFormat" );
+        if ( withLocale ) {
+            sb.append( "WithLocale" );
+        }
+        sb.append( "( " );
         if ( conversionContext.getNumberFormat() != null ) {
             sb.append( "\"" );
             sb.append( conversionContext.getNumberFormat() );
             sb.append( "\"" );
         }
+        if ( withLocale ) {
+            sb.append( ", " ).append( locale( conversionContext ) ).append( ".forLanguageTag( \"" );
+            sb.append( conversionContext.getLocale() );
+            sb.append( "\" )" );
+        }
 
         sb.append( " )" );
     }

processor/src/main/java/org/mapstruct/ap/internal/conversion/ConversionUtils.java

@@ -11,6 +11,7 @@ import java.net.URL;
 import java.sql.Time;
 import java.sql.Timestamp;
 import java.text.DecimalFormat;
+import java.text.DecimalFormatSymbols;
 import java.text.SimpleDateFormat;
 import java.time.LocalDate;
 import java.time.LocalDateTime;
@@ -279,4 +280,15 @@ public final class ConversionUtils {
         return typeReferenceName( conversionContext, URL.class );
     }
 
+    /**
+     * Name for {@link java.text.DecimalFormatSymbols}.
+     *
+     * @param conversionContext Conversion context
+     *
+     * @return Name or fully-qualified name.
+     */
+    public static String decimalFormatSymbols(ConversionContext conversionContext) {
+        return typeReferenceName( conversionContext, DecimalFormatSymbols.class );
+    }
+
 }

processor/src/main/java/org/mapstruct/ap/internal/conversion/CreateDecimalFormat.java

@@ -5,9 +5,11 @@
  */
 package org.mapstruct.ap.internal.conversion;
 
-import static org.mapstruct.ap.internal.util.Collections.asSet;
-
 import java.text.DecimalFormat;
+import java.text.DecimalFormatSymbols;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Locale;
 import java.util.Set;
 
 import org.mapstruct.ap.internal.model.HelperMethod;
@@ -16,6 +18,8 @@ import org.mapstruct.ap.internal.model.common.Type;
 import org.mapstruct.ap.internal.model.common.TypeFactory;
 import org.mapstruct.ap.internal.model.source.MappingMethodOptions;
 
+import static org.mapstruct.ap.internal.util.Collections.asSet;
+
 /**
  * HelperMethod that creates a {@link java.text.DecimalFormat}
  *
@@ -27,14 +31,31 @@ import org.mapstruct.ap.internal.model.source.MappingMethodOptions;
 public class CreateDecimalFormat extends HelperMethod {
 
     private final Parameter parameter;
+    private final Parameter localeParameter;
     private final Type returnType;
     private final Set<Type> importTypes;
 
-    public CreateDecimalFormat(TypeFactory typeFactory) {
+    public CreateDecimalFormat(TypeFactory typeFactory, boolean withLocale) {
         this.parameter = new Parameter( "numberFormat", typeFactory.getType( String.class ) );
+        this.localeParameter = withLocale ? new Parameter( "locale", typeFactory.getType( Locale.class ) ) : null;
         this.returnType = typeFactory.getType( DecimalFormat.class );
+        if ( withLocale ) {
+            this.importTypes = asSet(
+                parameter.getType(),
+                returnType,
+                typeFactory.getType( DecimalFormatSymbols.class ),
+                typeFactory.getType( Locale.class )
+            );
+        }
+        else {
             this.importTypes = asSet( parameter.getType(), returnType );
         }
+    }
+
+    @Override
+    public String getName() {
+        return localeParameter == null ? "createDecimalFormat" : "createDecimalFormatWithLocale";
+    }
 
     @Override
     public Set<Type> getImportTypes() {
@@ -60,4 +81,12 @@ public class CreateDecimalFormat extends HelperMethod {
     public String describe() {
         return null;
     }
+
+    @Override
+    public List<Parameter> getParameters() {
+        if ( localeParameter == null ) {
+            return super.getParameters();
+        }
+        return Arrays.asList( getParameter(), localeParameter );
+    }
 }

processor/src/main/java/org/mapstruct/ap/internal/conversion/DateToStringConversion.java

@@ -10,15 +10,18 @@ import java.text.SimpleDateFormat;
 import java.util.Collections;
 import java.util.Date;
 import java.util.List;
+import java.util.Locale;
+import java.util.Set;
 
 import org.mapstruct.ap.internal.model.HelperMethod;
 import org.mapstruct.ap.internal.model.TypeConversion;
 import org.mapstruct.ap.internal.model.common.Assignment;
 import org.mapstruct.ap.internal.model.common.ConversionContext;
+import org.mapstruct.ap.internal.model.common.Type;
 
-import static java.util.Arrays.asList;
+import static org.mapstruct.ap.internal.conversion.ConversionUtils.locale;
-import static org.mapstruct.ap.internal.util.Collections.asSet;
 import static org.mapstruct.ap.internal.conversion.ConversionUtils.simpleDateFormat;
+import static org.mapstruct.ap.internal.util.Collections.asSet;
 
 /**
  * Conversion between {@link String} and {@link Date}.
@@ -29,7 +32,7 @@ public class DateToStringConversion implements ConversionProvider {
 
     @Override
     public Assignment to(ConversionContext conversionContext) {
-        return new TypeConversion( asSet( conversionContext.getTypeFactory().getType( SimpleDateFormat.class ) ),
+        return new TypeConversion( getImportTypes( conversionContext ),
             Collections.emptyList(),
             getConversionExpression( conversionContext, "format" )
         );
@@ -37,8 +40,8 @@ public class DateToStringConversion implements ConversionProvider {
 
     @Override
     public Assignment from(ConversionContext conversionContext) {
-        return new TypeConversion( asSet( conversionContext.getTypeFactory().getType( SimpleDateFormat.class ) ),
+        return new TypeConversion( getImportTypes( conversionContext ),
-            asList( conversionContext.getTypeFactory().getType( ParseException.class ) ),
+            Collections.singletonList( conversionContext.getTypeFactory().getType( ParseException.class ) ),
             getConversionExpression( conversionContext, "parse" )
         );
     }
@@ -48,6 +51,17 @@ public class DateToStringConversion implements ConversionProvider {
         return Collections.emptyList();
     }
 
+    private Set<Type> getImportTypes(ConversionContext conversionContext) {
+        if ( conversionContext.getLocale() == null ) {
+            return Collections.singleton( conversionContext.getTypeFactory().getType( SimpleDateFormat.class ) );
+        }
+
+        return asSet(
+            conversionContext.getTypeFactory().getType( SimpleDateFormat.class ),
+            conversionContext.getTypeFactory().getType( Locale.class )
+        );
+    }
+
     private String getConversionExpression(ConversionContext conversionContext, String method) {
         StringBuilder conversionString = new StringBuilder( "new " );
         conversionString.append( simpleDateFormat( conversionContext ) );
@@ -57,6 +71,15 @@ public class DateToStringConversion implements ConversionProvider {
             conversionString.append( " \"" );
             conversionString.append( conversionContext.getDateFormat() );
             conversionString.append( "\"" );
+
+            if ( conversionContext.getLocale() != null ) {
+                conversionString.append( ", " ).append( locale( conversionContext ) ).append( ".forLanguageTag( \"" );
+                conversionString.append( conversionContext.getLocale() );
+                conversionString.append( "\" ) " );
+            }
+            else {
+                conversionString.append( " " );
+            }
         }
 
         conversionString.append( ")." );

processor/src/main/java/org/mapstruct/ap/internal/conversion/PrimitiveToStringConversion.java

@@ -6,7 +6,9 @@
 package org.mapstruct.ap.internal.conversion;
 
 import java.text.DecimalFormat;
+import java.text.DecimalFormatSymbols;
 import java.util.Collections;
+import java.util.Locale;
 import java.util.Set;
 
 import org.mapstruct.ap.internal.model.common.ConversionContext;
@@ -15,6 +17,9 @@ import org.mapstruct.ap.internal.util.NativeTypes;
 import org.mapstruct.ap.internal.util.Strings;
 
 import static org.mapstruct.ap.internal.conversion.ConversionUtils.decimalFormat;
+import static org.mapstruct.ap.internal.conversion.ConversionUtils.decimalFormatSymbols;
+import static org.mapstruct.ap.internal.conversion.ConversionUtils.locale;
+import static org.mapstruct.ap.internal.util.Collections.asSet;
 
 /**
  * Conversion between primitive types such as {@code byte} or {@code long} and
@@ -53,11 +58,17 @@ public class PrimitiveToStringConversion extends AbstractNumberToStringConversio
     @Override
     public Set<Type> getToConversionImportTypes(ConversionContext conversionContext) {
         if ( requiresDecimalFormat( conversionContext ) ) {
-            return Collections.singleton(
+            if ( conversionContext.getLocale() != null ) {
-                conversionContext.getTypeFactory().getType( DecimalFormat.class )
+                return asSet(
+                    conversionContext.getTypeFactory().getType( DecimalFormat.class ),
+                    conversionContext.getTypeFactory().getType( DecimalFormatSymbols.class ),
+                    conversionContext.getTypeFactory().getType( Locale.class )
                 );
             }
 
+            return Collections.singleton( conversionContext.getTypeFactory().getType( DecimalFormat.class ) );
+        }
+
         return Collections.emptySet();
     }
 
@@ -80,11 +91,17 @@ public class PrimitiveToStringConversion extends AbstractNumberToStringConversio
     @Override
     protected Set<Type> getFromConversionImportTypes(ConversionContext conversionContext) {
         if ( requiresDecimalFormat( conversionContext ) ) {
-            return Collections.singleton(
+            if ( conversionContext.getLocale() != null ) {
-                conversionContext.getTypeFactory().getType( DecimalFormat.class )
+                return asSet(
+                    conversionContext.getTypeFactory().getType( DecimalFormat.class ),
+                    conversionContext.getTypeFactory().getType( DecimalFormatSymbols.class ),
+                    conversionContext.getTypeFactory().getType( Locale.class )
                 );
             }
 
+            return Collections.singleton( conversionContext.getTypeFactory().getType( DecimalFormat.class ) );
+        }
+
         return Collections.emptySet();
     }
 
@@ -97,6 +114,16 @@ public class PrimitiveToStringConversion extends AbstractNumberToStringConversio
             sb.append( "\"" );
             sb.append( conversionContext.getNumberFormat() );
             sb.append( "\"" );
+
+            if ( conversionContext.getLocale() != null ) {
+                sb.append( ", " )
+                    .append( decimalFormatSymbols( conversionContext ) )
+                    .append( ".getInstance( " )
+                    .append( locale( conversionContext ) )
+                    .append( ".forLanguageTag( \"" )
+                    .append( conversionContext.getLocale() )
+                    .append( " \" ) )" );
+            }
         }
 
         sb.append( " )" );

processor/src/main/java/org/mapstruct/ap/internal/conversion/WrapperToStringConversion.java

@@ -6,7 +6,9 @@
 package org.mapstruct.ap.internal.conversion;
 
 import java.text.DecimalFormat;
+import java.text.DecimalFormatSymbols;
 import java.util.Collections;
+import java.util.Locale;
 import java.util.Set;
 
 import org.mapstruct.ap.internal.model.common.ConversionContext;
@@ -15,6 +17,9 @@ import org.mapstruct.ap.internal.util.NativeTypes;
 import org.mapstruct.ap.internal.util.Strings;
 
 import static org.mapstruct.ap.internal.conversion.ConversionUtils.decimalFormat;
+import static org.mapstruct.ap.internal.conversion.ConversionUtils.decimalFormatSymbols;
+import static org.mapstruct.ap.internal.conversion.ConversionUtils.locale;
+import static org.mapstruct.ap.internal.util.Collections.asSet;
 
 /**
  * Conversion between wrapper types such as {@link Integer} and {@link String}.
@@ -52,11 +57,17 @@ public class WrapperToStringConversion extends AbstractNumberToStringConversion
     @Override
     public Set<Type> getToConversionImportTypes(ConversionContext conversionContext) {
         if ( requiresDecimalFormat( conversionContext ) ) {
-            return Collections.singleton(
+            if ( conversionContext.getLocale() != null ) {
-                conversionContext.getTypeFactory().getType( DecimalFormat.class )
+                return asSet(
+                    conversionContext.getTypeFactory().getType( DecimalFormat.class ),
+                    conversionContext.getTypeFactory().getType( DecimalFormatSymbols.class ),
+                    conversionContext.getTypeFactory().getType( Locale.class )
                 );
             }
 
+            return Collections.singleton( conversionContext.getTypeFactory().getType( DecimalFormat.class ) );
+        }
+
         return Collections.emptySet();
     }
 
@@ -79,11 +90,17 @@ public class WrapperToStringConversion extends AbstractNumberToStringConversion
     @Override
     protected Set<Type> getFromConversionImportTypes(ConversionContext conversionContext) {
         if ( requiresDecimalFormat( conversionContext ) ) {
-            return Collections.singleton(
+            if ( conversionContext.getLocale() != null ) {
-                conversionContext.getTypeFactory().getType( DecimalFormat.class )
+                return asSet(
+                    conversionContext.getTypeFactory().getType( DecimalFormat.class ),
+                    conversionContext.getTypeFactory().getType( DecimalFormatSymbols.class ),
+                    conversionContext.getTypeFactory().getType( Locale.class )
                 );
             }
 
+            return Collections.singleton( conversionContext.getTypeFactory().getType( DecimalFormat.class ) );
+        }
+
         return Collections.emptySet();
     }
 
@@ -96,6 +113,16 @@ public class WrapperToStringConversion extends AbstractNumberToStringConversion
             sb.append( "\"" );
             sb.append( conversionContext.getNumberFormat() );
             sb.append( "\"" );
+
+            if ( conversionContext.getLocale() != null ) {
+                sb.append( ", " )
+                    .append( decimalFormatSymbols( conversionContext ) )
+                    .append( ".getInstance( " )
+                    .append( locale( conversionContext ) )
+                    .append( ".forLanguageTag( \"" )
+                    .append( conversionContext.getLocale() )
+                    .append( " \" ) )" );
+            }
         }
 
         sb.append( " )" );

processor/src/main/java/org/mapstruct/ap/internal/model/common/ConversionContext.java

@@ -32,6 +32,8 @@ public interface ConversionContext {
 
     String getNumberFormat();
 
+    String getLocale();
+
     TypeFactory getTypeFactory();
 
 }

processor/src/main/java/org/mapstruct/ap/internal/model/common/DefaultConversionContext.java

@@ -21,6 +21,7 @@ public class DefaultConversionContext implements ConversionContext {
     private final FormattingParameters formattingParameters;
     private final String dateFormat;
     private final String numberFormat;
+    private final String locale;
     private final TypeFactory typeFactory;
 
     public DefaultConversionContext(TypeFactory typeFactory, FormattingMessager messager, Type sourceType,
@@ -32,6 +33,7 @@ public class DefaultConversionContext implements ConversionContext {
         this.formattingParameters = formattingParameters;
         this.dateFormat = this.formattingParameters.getDate();
         this.numberFormat = this.formattingParameters.getNumber();
+        this.locale = this.formattingParameters.getLocale();
         validateDateFormat();
     }
 
@@ -64,6 +66,11 @@ public class DefaultConversionContext implements ConversionContext {
         return numberFormat;
     }
 
+    @Override
+    public String getLocale() {
+        return locale != null ? locale.toString() : null;
+    }
+
     @Override
     public String getDateFormat() {
         return dateFormat;

processor/src/main/java/org/mapstruct/ap/internal/model/common/FormattingParameters.java

@@ -15,21 +15,23 @@ import javax.lang.model.element.Element;
  */
 public class FormattingParameters {
 
-    public static final FormattingParameters EMPTY = new FormattingParameters( null, null, null, null, null );
+    public static final FormattingParameters EMPTY = new FormattingParameters( null, null, null, null, null, null );
 
     private final String date;
     private final String number;
     private final AnnotationMirror mirror;
     private final AnnotationValue dateAnnotationValue;
     private final Element element;
+    private final String locale;
 
     public FormattingParameters(String date, String number, AnnotationMirror mirror,
-        AnnotationValue dateAnnotationValue, Element element) {
+        AnnotationValue dateAnnotationValue, Element element, String locale) {
         this.date = date;
         this.number = number;
         this.mirror = mirror;
         this.dateAnnotationValue = dateAnnotationValue;
         this.element = element;
+        this.locale = locale;
     }
 
     public String getDate() {
@@ -51,4 +53,8 @@ public class FormattingParameters {
     public Element getElement() {
         return element;
     }
+
+    public String getLocale() {
+        return locale;
+    }
 }

processor/src/main/java/org/mapstruct/ap/internal/model/source/IterableMappingOptions.java

@@ -55,7 +55,8 @@ public class IterableMappingOptions extends DelegatingOptions {
             iterableMapping.numberFormat().get(),
             iterableMapping.mirror(),
             iterableMapping.dateFormat().getAnnotationValue(),
-            method
+            method,
+            iterableMapping.locale().getValue()
         );
 
         IterableMappingOptions options =

processor/src/main/java/org/mapstruct/ap/internal/model/source/MapMappingOptions.java

@@ -8,14 +8,14 @@ package org.mapstruct.ap.internal.model.source;
 import java.util.Optional;
 import javax.lang.model.element.AnnotationMirror;
 import javax.lang.model.element.ExecutableElement;
-import org.mapstruct.ap.internal.util.ElementUtils;
-import org.mapstruct.ap.internal.util.TypeUtils;
 
-import org.mapstruct.ap.internal.model.common.FormattingParameters;
 import org.mapstruct.ap.internal.gem.MapMappingGem;
 import org.mapstruct.ap.internal.gem.NullValueMappingStrategyGem;
+import org.mapstruct.ap.internal.model.common.FormattingParameters;
+import org.mapstruct.ap.internal.util.ElementUtils;
 import org.mapstruct.ap.internal.util.FormattingMessager;
 import org.mapstruct.ap.internal.util.Message;
+import org.mapstruct.ap.internal.util.TypeUtils;
 import org.mapstruct.tools.gem.GemValue;
 
 /**
@@ -47,6 +47,8 @@ public class MapMappingOptions extends DelegatingOptions {
             return options;
         }
 
+        String locale = mapMapping.locale().getValue();
+
         SelectionParameters keySelection = new SelectionParameters(
             mapMapping.keyQualifiedBy().get(),
             mapMapping.keyQualifiedByName().get(),
@@ -66,7 +68,8 @@ public class MapMappingOptions extends DelegatingOptions {
             mapMapping.keyNumberFormat().get(),
             mapMapping.mirror(),
             mapMapping.keyDateFormat().getAnnotationValue(),
-            method
+            method,
+            locale
         );
 
         FormattingParameters valueFormatting = new FormattingParameters(
@@ -74,7 +77,8 @@ public class MapMappingOptions extends DelegatingOptions {
             mapMapping.valueNumberFormat().get(),
             mapMapping.mirror(),
             mapMapping.valueDateFormat().getAnnotationValue(),
-            method
+            method,
+            locale
         );
 
         MapMappingOptions options = new MapMappingOptions(

processor/src/main/java/org/mapstruct/ap/internal/model/source/MappingOptions.java

@@ -18,16 +18,16 @@ import javax.lang.model.element.AnnotationMirror;
 import javax.lang.model.element.AnnotationValue;
 import javax.lang.model.element.Element;
 import javax.lang.model.element.ExecutableElement;
-import org.mapstruct.ap.internal.util.ElementUtils;
-import org.mapstruct.ap.internal.util.TypeUtils;
 
 import org.mapstruct.ap.internal.gem.MappingGem;
 import org.mapstruct.ap.internal.gem.MappingsGem;
 import org.mapstruct.ap.internal.gem.NullValueCheckStrategyGem;
 import org.mapstruct.ap.internal.gem.NullValuePropertyMappingStrategyGem;
 import org.mapstruct.ap.internal.model.common.FormattingParameters;
+import org.mapstruct.ap.internal.util.ElementUtils;
 import org.mapstruct.ap.internal.util.FormattingMessager;
 import org.mapstruct.ap.internal.util.Message;
+import org.mapstruct.ap.internal.util.TypeUtils;
 import org.mapstruct.tools.gem.GemValue;
 
 /**
@@ -118,6 +118,8 @@ public class MappingOptions extends DelegatingOptions {
         String conditionExpression = getConditionExpression( mapping, method, messager );
         String dateFormat = mapping.dateFormat().getValue();
         String numberFormat = mapping.numberFormat().getValue();
+        String locale = mapping.locale().getValue();
+
         String defaultValue = mapping.defaultValue().getValue();
 
         Set<String> dependsOn = mapping.dependsOn().hasValue() ?
@@ -129,7 +131,8 @@ public class MappingOptions extends DelegatingOptions {
             numberFormat,
             mapping.mirror(),
             mapping.dateFormat().getAnnotationValue(),
-            method
+            method,
+            locale
         );
         SelectionParameters selectionParams = new SelectionParameters(
             mapping.qualifiedBy().get(),

processor/src/main/resources/org/mapstruct/ap/internal/conversion/CreateDecimalFormat.ftl

@@ -5,9 +5,10 @@
     Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
 
 -->
-private DecimalFormat ${name}( String numberFormat ) {
+<#-- @ftlvariable name="" type="org.mapstruct.ap.internal.model.SupportingMappingMethod" -->
+private DecimalFormat ${name}( <#list parameters as param><@includeModel object=param/><#if param_has_next>, </#if></#list> ) {
 
-    DecimalFormat df = new DecimalFormat( numberFormat );
+    DecimalFormat df = new DecimalFormat( numberFormat<#if parameters.size() &gt; 1>, DecimalFormatSymbols.getInstance( locale )</#if> );
     df.setParseBigDecimal( true );
     return df;
 }

processor/src/test/java/org/mapstruct/ap/internal/model/common/DefaultConversionContextTest.java

@@ -70,7 +70,7 @@ public class DefaultConversionContextTest {
             statefulMessagerMock,
             type,
             type,
-            new FormattingParameters( "qwertz", null, null, null, null )
+            new FormattingParameters( "qwertz", null, null, null, null, null )
         );
         assertThat( statefulMessagerMock.getLastKindPrinted() ).isEqualTo( Diagnostic.Kind.ERROR );
     }
@@ -84,7 +84,7 @@ public class DefaultConversionContextTest {
             statefulMessagerMock,
             type,
             type,
-            new FormattingParameters( null, null, null, null, null )
+            new FormattingParameters( null, null, null, null, null, null )
         );
         assertThat( statefulMessagerMock.getLastKindPrinted() ).isNull();
     }
@@ -97,7 +97,7 @@ public class DefaultConversionContextTest {
             statefulMessagerMock,
             type,
             type,
-            new FormattingParameters( "qwertz", null, null, null, null )
+            new FormattingParameters( "qwertz", null, null, null, null, null )
         );
         assertThat( statefulMessagerMock.getLastKindPrinted() ).isNull();
     }

processor/src/test/java/org/mapstruct/ap/test/conversion/date/DateConversionTest.java

@@ -54,6 +54,21 @@ public class DateConversionTest {
         assertThat( target.getAnotherDate() ).isEqualTo( "14.02.13 00:00" );
     }
 
+    @ProcessorTest
+    @EnabledOnJre( JRE.JAVA_8 )
+    // See https://bugs.openjdk.java.net/browse/JDK-8211262, there is a difference in the default formats on Java 9+
+    public void shouldApplyDateFormatForConversionsWithCustomLocale() {
+        Source source = new Source();
+        source.setDate( new GregorianCalendar( 2013, Calendar.JULY, 6 ).getTime() );
+        source.setAnotherDate( new GregorianCalendar( 2013, Calendar.FEBRUARY, 14 ).getTime() );
+
+        Target target = SourceTargetMapper.INSTANCE.sourceToTargetWithCustomLocale( source );
+
+        assertThat( target ).isNotNull();
+        assertThat( target.getDate() ).isEqualTo( "juillet 06, 2013" );
+        assertThat( target.getAnotherDate() ).isEqualTo( "14.02.13, 00:00" );
+    }
+
     @ProcessorTest
     @EnabledForJreRange(min = JRE.JAVA_11)
     // See https://bugs.openjdk.java.net/browse/JDK-8211262, there is a difference in the default formats on Java 9+
@@ -69,6 +84,21 @@ public class DateConversionTest {
         assertThat( target.getAnotherDate() ).isEqualTo( "14.02.13, 00:00" );
     }
 
+    @ProcessorTest
+    @EnabledForJreRange(min = JRE.JAVA_11)
+    // See https://bugs.openjdk.java.net/browse/JDK-8211262, there is a difference in the default formats on Java 9+
+    public void shouldApplyDateFormatForConversionsJdk11WithCustomLocale() {
+        Source source = new Source();
+        source.setDate( new GregorianCalendar( 2013, Calendar.JULY, 6 ).getTime() );
+        source.setAnotherDate( new GregorianCalendar( 2013, Calendar.FEBRUARY, 14 ).getTime() );
+
+        Target target = SourceTargetMapper.INSTANCE.sourceToTargetWithCustomLocale( source );
+
+        assertThat( target ).isNotNull();
+        assertThat( target.getDate() ).isEqualTo( "juillet 06, 2013" );
+        assertThat( target.getAnotherDate() ).isEqualTo( "14.02.13, 00:00" );
+    }
+
     @ProcessorTest
     @EnabledOnJre(JRE.JAVA_8)
     // See https://bugs.openjdk.java.net/browse/JDK-8211262, there is a difference in the default formats on Java 9+
@@ -86,6 +116,23 @@ public class DateConversionTest {
         );
     }
 
+    @ProcessorTest
+    @EnabledOnJre(JRE.JAVA_8)
+    // See https://bugs.openjdk.java.net/browse/JDK-8211262, there is a difference in the default formats on Java 9+
+    public void shouldApplyDateFormatForConversionInReverseMappingWithCustomLocale() {
+        Target target = new Target();
+        target.setDate( "juillet 06, 2013" );
+        target.setAnotherDate( "14.02.13 8:30" );
+
+        Source source = SourceTargetMapper.INSTANCE.targetToSourceWithCustomLocale( target );
+
+        assertThat( source ).isNotNull();
+        assertThat( source.getDate() ).isEqualTo( new GregorianCalendar( 2013, Calendar.JULY, 6 ).getTime() );
+        assertThat( source.getAnotherDate() ).isEqualTo(
+            new GregorianCalendar( 2013, Calendar.FEBRUARY, 14, 8, 30 ).getTime()
+        );
+    }
+
     @ProcessorTest
     @EnabledForJreRange(min = JRE.JAVA_11)
     // See https://bugs.openjdk.java.net/browse/JDK-8211262, there is a difference in the default formats on Java 9+
@@ -103,6 +150,23 @@ public class DateConversionTest {
         );
     }
 
+    @ProcessorTest
+    @EnabledForJreRange(min = JRE.JAVA_11)
+    // See https://bugs.openjdk.java.net/browse/JDK-8211262, there is a difference in the default formats on Java 9+
+    public void shouldApplyDateFormatForConversionInReverseMappingJdk11WithCustomLocale() {
+        Target target = new Target();
+        target.setDate( "juillet 06, 2013" );
+        target.setAnotherDate( "14.02.13, 8:30" );
+
+        Source source = SourceTargetMapper.INSTANCE.targetToSourceWithCustomLocale( target );
+
+        assertThat( source ).isNotNull();
+        assertThat( source.getDate() ).isEqualTo( new GregorianCalendar( 2013, Calendar.JULY, 6 ).getTime() );
+        assertThat( source.getAnotherDate() ).isEqualTo(
+            new GregorianCalendar( 2013, Calendar.FEBRUARY, 14, 8, 30 ).getTime()
+        );
+    }
+
     @ProcessorTest
     public void shouldApplyStringConversionForIterableMethod() {
         List<Date> dates = Arrays.asList(
@@ -117,6 +181,20 @@ public class DateConversionTest {
         assertThat( stringDates ).containsExactly( "06.07.2013", "14.02.2013", "11.04.2013" );
     }
 
+    @ProcessorTest
+    public void shouldApplyStringConversionForIterableMethodWithCustomLocale() {
+        List<Date> dates = Arrays.asList(
+            new GregorianCalendar( 2013, Calendar.JULY, 6 ).getTime(),
+            new GregorianCalendar( 2013, Calendar.FEBRUARY, 14 ).getTime(),
+            new GregorianCalendar( 2013, Calendar.APRIL, 11 ).getTime()
+        );
+
+        List<String> stringDates = SourceTargetMapper.INSTANCE.stringListToDateListWithCustomLocale( dates );
+
+        assertThat( stringDates ).isNotNull();
+        assertThat( stringDates ).containsExactly( "juillet 06, 2013", "février 14, 2013", "avril 11, 2013" );
+    }
+
     @ProcessorTest
     public void shouldApplyStringConversionForArrayMethod() {
         List<Date> dates = Arrays.asList(
@@ -131,6 +209,20 @@ public class DateConversionTest {
         assertThat( stringDates ).isEqualTo( new String[]{ "06.07.2013", "14.02.2013", "11.04.2013" } );
     }
 
+    @ProcessorTest
+    public void shouldApplyStringConversionForArrayMethodWithCustomLocale() {
+        List<Date> dates = Arrays.asList(
+            new GregorianCalendar( 2013, Calendar.JULY, 6 ).getTime(),
+            new GregorianCalendar( 2013, Calendar.FEBRUARY, 14 ).getTime(),
+            new GregorianCalendar( 2013, Calendar.APRIL, 11 ).getTime()
+        );
+
+        String[] stringDates = SourceTargetMapper.INSTANCE.stringListToDateArrayWithCustomLocale( dates );
+
+        assertThat( stringDates ).isNotNull();
+        assertThat( stringDates ).isEqualTo( new String[]{ "juillet 06, 2013", "février 14, 2013", "avril 11, 2013" } );
+    }
+
     @ProcessorTest
     public void shouldApplyStringConversionForReverseIterableMethod() {
         List<String> stringDates = Arrays.asList( "06.07.2013", "14.02.2013", "11.04.2013" );
@@ -145,6 +237,20 @@ public class DateConversionTest {
         );
     }
 
+    @ProcessorTest
+    public void shouldApplyStringConversionForReverseIterableMethodWithCustomLocale() {
+        List<String> stringDates = Arrays.asList( "juillet 06, 2013", "février 14, 2013", "avril 11, 2013" );
+
+        List<Date> dates = SourceTargetMapper.INSTANCE.dateListToStringListWithCustomLocale( stringDates );
+
+        assertThat( dates ).isNotNull();
+        assertThat( dates ).containsExactly(
+            new GregorianCalendar( 2013, Calendar.JULY, 6 ).getTime(),
+            new GregorianCalendar( 2013, Calendar.FEBRUARY, 14 ).getTime(),
+            new GregorianCalendar( 2013, Calendar.APRIL, 11 ).getTime()
+        );
+    }
+
     @ProcessorTest
     public void shouldApplyStringConversionForReverseArrayMethod() {
         String[] stringDates = new String[]{ "06.07.2013", "14.02.2013", "11.04.2013" };
@@ -159,6 +265,20 @@ public class DateConversionTest {
         );
     }
 
+    @ProcessorTest
+    public void shouldApplyStringConversionForReverseArrayMethodWithCustomLocale() {
+        String[] stringDates = new String[]{ "juillet 06, 2013", "février 14, 2013", "avril 11, 2013" };
+
+        List<Date> dates = SourceTargetMapper.INSTANCE.stringArrayToDateListWithCustomLocale( stringDates );
+
+        assertThat( dates ).isNotNull();
+        assertThat( dates ).containsExactly(
+            new GregorianCalendar( 2013, Calendar.JULY, 6 ).getTime(),
+            new GregorianCalendar( 2013, Calendar.FEBRUARY, 14 ).getTime(),
+            new GregorianCalendar( 2013, Calendar.APRIL, 11 ).getTime()
+        );
+    }
+
     @ProcessorTest
     public void shouldApplyStringConversionForReverseArrayArrayMethod() {
          Date[] dates = new Date[]{

processor/src/test/java/org/mapstruct/ap/test/conversion/date/SourceTargetMapper.java

@@ -22,21 +22,39 @@ public interface SourceTargetMapper {
     @Mapping(target = "date", dateFormat = "dd.MM.yyyy")
     Target sourceToTarget(Source source);
 
-    @InheritInverseConfiguration
+    @Mapping(target = "date", dateFormat = "MMMM dd, yyyy", locale = "fr")
+    Target sourceToTargetWithCustomLocale(Source source);
+
+    @InheritInverseConfiguration(name = "sourceToTarget")
     Source targetToSource(Target target);
 
+    @InheritInverseConfiguration(name = "sourceToTargetWithCustomLocale")
+    Source targetToSourceWithCustomLocale(Target target);
+
     @IterableMapping(dateFormat = "dd.MM.yyyy")
     List<String> stringListToDateList(List<Date> dates);
 
+    @IterableMapping(dateFormat = "MMMM dd, yyyy", locale = "fr")
+    List<String> stringListToDateListWithCustomLocale(List<Date> dates);
+
     @IterableMapping(dateFormat = "dd.MM.yyyy")
     String[] stringListToDateArray(List<Date> dates);
 
-    @InheritInverseConfiguration
+    @IterableMapping(dateFormat = "MMMM dd, yyyy", locale = "fr")
+    String[] stringListToDateArrayWithCustomLocale(List<Date> dates);
+
+    @InheritInverseConfiguration(name = "stringListToDateList")
     List<Date> dateListToStringList(List<String> strings);
 
-    @InheritInverseConfiguration
+    @InheritInverseConfiguration(name = "stringListToDateListWithCustomLocale")
+    List<Date> dateListToStringListWithCustomLocale(List<String> strings);
+
+    @InheritInverseConfiguration(name = "stringListToDateArray")
     List<Date> stringArrayToDateList(String[] dates);
 
+    @InheritInverseConfiguration(name = "stringListToDateArrayWithCustomLocale")
+    List<Date> stringArrayToDateListWithCustomLocale(String[] dates);
+
     @IterableMapping(dateFormat = "dd.MM.yyyy")
     String[] dateArrayToStringArray(Date[] dates);
 

processor/src/test/java/org/mapstruct/ap/test/conversion/numbers/NumberFormatConversionTest.java

@@ -7,14 +7,15 @@ package org.mapstruct.ap.test.conversion.numbers;
 
 import java.math.BigDecimal;
 import java.math.BigInteger;
-import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
+import org.junit.jupiter.api.extension.RegisterExtension;
 import org.junitpioneer.jupiter.DefaultLocale;
 import org.mapstruct.ap.testutil.ProcessorTest;
 import org.mapstruct.ap.testutil.WithClasses;
+import org.mapstruct.ap.testutil.runner.GeneratedSource;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.entry;
@@ -27,6 +28,10 @@ import static org.assertj.core.api.Assertions.entry;
 @DefaultLocale("en")
 public class NumberFormatConversionTest {
 
+    @RegisterExtension
+    final GeneratedSource generatedSource = new GeneratedSource()
+        .addComparisonToFixtureFor( SourceTargetMapper.class );
+
     @ProcessorTest
     public void shouldApplyStringConversions() {
         Source source = new Source();
@@ -68,6 +73,47 @@ public class NumberFormatConversionTest {
         assertThat( target.getBigInteger1() ).isEqualTo( "1.23456789E12" );
     }
 
+    @ProcessorTest
+    public void shouldApplyStringConversionsWithCustomLocale() {
+        Source source = new Source();
+        source.setI( 1 );
+        source.setIi( 2 );
+        source.setD( 3.0 );
+        source.setDd( 4.0 );
+        source.setF( 3.0f );
+        source.setFf( 4.0f );
+        source.setL( 5L );
+        source.setLl( 6L );
+        source.setB( (byte) 7 );
+        source.setBb( (byte) 8 );
+
+        source.setComplex1( 345346.456756 );
+        source.setComplex2( 5007034.3 );
+
+        source.setBigDecimal1( new BigDecimal( "987E-20" ) );
+        source.setBigInteger1( new BigInteger( "1234567890000" ) );
+
+        Target target = SourceTargetMapper.INSTANCE.sourceToTargetWithCustomLocale( source );
+
+        assertThat( target ).isNotNull();
+        assertThat( target.getI() ).isEqualTo( "1.00" );
+        assertThat( target.getIi() ).isEqualTo( "2.00" );
+        assertThat( target.getD() ).isEqualTo( "3.00" );
+        assertThat( target.getDd() ).isEqualTo( "4.00" );
+        assertThat( target.getF() ).isEqualTo( "3.00" );
+        assertThat( target.getFf() ).isEqualTo( "4.00" );
+        assertThat( target.getL() ).isEqualTo( "5.00" );
+        assertThat( target.getLl() ).isEqualTo( "6.00" );
+        assertThat( target.getB() ).isEqualTo( "7.00" );
+        assertThat( target.getBb() ).isEqualTo( "8.00" );
+
+        assertThat( target.getComplex1() ).isEqualTo( "345.35E3" );
+        assertThat( target.getComplex2() ).isEqualTo( "$5007034.30" );
+
+        assertThat( target.getBigDecimal1() ).isEqualTo( "9,87E-18" );
+        assertThat( target.getBigInteger1() ).isEqualTo( "1,23456789E12" );
+    }
+
     @ProcessorTest
     public void shouldApplyReverseStringConversions() {
         Target target = new Target();
@@ -109,17 +155,73 @@ public class NumberFormatConversionTest {
         assertThat( source.getBigInteger1() ).isEqualTo( new BigInteger( "1234567890000" ) );
     }
 
+    @ProcessorTest
+    public void shouldApplyReverseStringConversionsWithCustomLocale() {
+        Target target = new Target();
+        target.setI( "1.00" );
+        target.setIi( "2.00" );
+        target.setD( "3.00" );
+        target.setDd( "4.00" );
+        target.setF( "3.00" );
+        target.setFf( "4.00" );
+        target.setL( "5.00" );
+        target.setLl( "6.00" );
+        target.setB( "7.00" );
+        target.setBb( "8.00" );
+
+        target.setComplex1( "345.35E3" );
+        target.setComplex2( "$5007034.30" );
+
+        target.setBigDecimal1( "9,87E-18" );
+        target.setBigInteger1( "1,23456789E12" );
+
+        Source source = SourceTargetMapper.INSTANCE.targetToSourceWithCustomLocale( target );
+
+        assertThat( source ).isNotNull();
+        assertThat( source.getI() ).isEqualTo( 1 );
+        assertThat( source.getIi() ).isEqualTo( Integer.valueOf( 2 ) );
+        assertThat( source.getD() ).isEqualTo( 3.0 );
+        assertThat( source.getDd() ).isEqualTo( Double.valueOf( 4.0 ) );
+        assertThat( source.getF() ).isEqualTo( 3.0f );
+        assertThat( source.getFf() ).isEqualTo( Float.valueOf( 4.0f ) );
+        assertThat( source.getL() ).isEqualTo( 5L );
+        assertThat( source.getLl() ).isEqualTo( Long.valueOf( 6L ) );
+        assertThat( source.getB() ).isEqualTo( (byte) 7 );
+        assertThat( source.getBb() ).isEqualTo( (byte) 8 );
+
+        assertThat( source.getComplex1() ).isEqualTo( 345350.0 );
+        assertThat( source.getComplex2() ).isEqualTo( 5007034.3 );
+
+        assertThat( source.getBigDecimal1() ).isEqualTo( new BigDecimal( "987E-20" ) );
+        assertThat( source.getBigInteger1() ).isEqualTo( new BigInteger( "1234567890000" ) );
+    }
+
     @ProcessorTest
     public void shouldApplyStringConversionsToIterables() {
 
-        List<String> target = SourceTargetMapper.INSTANCE.sourceToTarget( Arrays.asList( 2f ) );
+        List<String> target = SourceTargetMapper.INSTANCE.sourceToTarget( List.of( 2f ) );
 
         assertThat( target ).hasSize( 1 );
-        assertThat( target ).isEqualTo( Arrays.asList( "2.00" ) );
+        assertThat( target ).isEqualTo( List.of( "2.00" ) );
 
         List<Float> source = SourceTargetMapper.INSTANCE.targetToSource( target );
         assertThat( source  ).hasSize( 1 );
-        assertThat( source ).isEqualTo( Arrays.asList( 2.00f ) );
+        assertThat( source ).isEqualTo( List.of( 2.00f ) );
+    }
+
+    @ProcessorTest
+    public void shouldApplyStringConversionsToIterablesWithCustomLocale() {
+
+        List<String> target = SourceTargetMapper.INSTANCE.sourceToTargetWithCustomLocale(
+            List.of( new BigDecimal("987E-20") )
+        );
+
+        assertThat( target ).hasSize( 1 );
+        assertThat( target ).isEqualTo( List.of( "9,87E-18" ) );
+
+        List<BigDecimal> source = SourceTargetMapper.INSTANCE.targetToSourceWithCustomLocale( target );
+        assertThat( source  ).hasSize( 1 );
+        assertThat( source ).isEqualTo( List.of( new BigDecimal("987E-20") ) );
     }
 
     @ProcessorTest
@@ -137,4 +239,20 @@ public class NumberFormatConversionTest {
         assertThat( source2 ).contains( entry( 1.00f, 2f ) );
 
     }
+
+    @ProcessorTest
+    public void shouldApplyStringConversionsToMapsWithCustomLocale() {
+
+        Map<BigDecimal, BigDecimal> source1 = new HashMap<>();
+        source1.put( new BigDecimal( "987E-20" ), new BigDecimal( "97E-10" ) );
+
+        Map<String, String> target = SourceTargetMapper.INSTANCE.sourceToTargetWithCustomLocale( source1 );
+        assertThat( target  ).hasSize( 1 );
+        assertThat( target ).contains( entry( "9,87E-18", "9,7E-9" ) );
+
+        Map<BigDecimal, BigDecimal> source2 = SourceTargetMapper.INSTANCE.targetToSourceWithCustomLocale( target );
+        assertThat( source2  ).hasSize( 1 );
+        assertThat( source2 ).contains( entry( new BigDecimal( "987E-20" ), new BigDecimal( "97E-10" ) ) );
+
+    }
 }

processor/src/test/java/org/mapstruct/ap/test/conversion/numbers/SourceTargetMapper.java

@@ -5,6 +5,7 @@
  */
 package org.mapstruct.ap.test.conversion.numbers;
 
+import java.math.BigDecimal;
 import java.util.List;
 import java.util.Map;
 import org.mapstruct.InheritInverseConfiguration;
@@ -41,21 +42,55 @@ public interface SourceTargetMapper {
     } )
     Target sourceToTarget(Source source);
 
-    @InheritInverseConfiguration
+    @Mappings( {
+        @Mapping( target = "i", numberFormat = NUMBER_FORMAT, locale = "ru" ),
+        @Mapping( target = "ii", numberFormat = NUMBER_FORMAT, locale = "ru" ),
+        @Mapping( target = "d", numberFormat = NUMBER_FORMAT, locale = "ru" ),
+        @Mapping( target = "dd", numberFormat = NUMBER_FORMAT, locale = "ru" ),
+        @Mapping( target = "f", numberFormat = NUMBER_FORMAT, locale = "ru" ),
+        @Mapping( target = "ff", numberFormat = NUMBER_FORMAT, locale = "ru" ),
+        @Mapping( target = "l", numberFormat = NUMBER_FORMAT, locale = "ru" ),
+        @Mapping( target = "ll", numberFormat = NUMBER_FORMAT, locale = "ru" ),
+        @Mapping( target = "b", numberFormat = NUMBER_FORMAT, locale = "ru" ),
+        @Mapping( target = "bb", numberFormat = NUMBER_FORMAT, locale = "ru" ),
+        @Mapping( target = "complex1", numberFormat = "##0.##E0", locale = "ru" ),
+        @Mapping( target = "complex2", numberFormat = "$#.00", locale = "ru" ),
+        @Mapping( target = "bigDecimal1", numberFormat = "#0.#E0", locale = "ru" ),
+        @Mapping( target = "bigInteger1", numberFormat = "0.#############E0", locale = "ru" )
+
+    } )
+    Target sourceToTargetWithCustomLocale(Source source);
+
+    @InheritInverseConfiguration( name = "sourceToTarget" )
     Source targetToSource(Target target);
 
+    @InheritInverseConfiguration( name = "sourceToTargetWithCustomLocale" )
+    Source targetToSourceWithCustomLocale(Target target);
+
     @IterableMapping( numberFormat = NUMBER_FORMAT )
     List<String> sourceToTarget(List<Float> source);
 
-    @InheritInverseConfiguration
+    @InheritInverseConfiguration( name = "sourceToTarget" )
     List<Float> targetToSource(List<String> source);
 
+    @IterableMapping( numberFormat = "#0.#E0", locale = "fr" )
+    List<String> sourceToTargetWithCustomLocale(List<BigDecimal> source);
+
+    @InheritInverseConfiguration( name = "sourceToTargetWithCustomLocale" )
+    List<BigDecimal> targetToSourceWithCustomLocale(List<String> source);
+
     @MapMapping( keyNumberFormat = NUMBER_FORMAT, valueNumberFormat = "##" )
     Map<String, String> sourceToTarget(Map<Float, Float> source);
 
-    @InheritInverseConfiguration
+    @MapMapping( keyNumberFormat = "#0.#E0", valueNumberFormat = "0.#############E0", locale = "fr" )
+    Map<String, String> sourceToTargetWithCustomLocale(Map<BigDecimal, BigDecimal> source);
+
+    @InheritInverseConfiguration( name = "sourceToTarget" )
     Map<Float, Float> targetToSource(Map<String, String> source);
 
+    @InheritInverseConfiguration( name = "sourceToTargetWithCustomLocale" )
+    Map<BigDecimal, BigDecimal> targetToSourceWithCustomLocale(Map<String, String> source);
+
 }
 
 

processor/src/test/resources/fixtures/21/org/mapstruct/ap/test/conversion/numbers/SourceTargetMapperImpl.java

@@ -0,0 +1,525 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.test.conversion.numbers;
+
+import java.math.BigDecimal;
+import java.text.DecimalFormat;
+import java.text.DecimalFormatSymbols;
+import java.text.ParseException;
+import java.util.ArrayList;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+import javax.annotation.processing.Generated;
+
+@Generated(
+    value = "org.mapstruct.ap.MappingProcessor",
+    date = "2024-09-14T11:37:30+0300",
+    comments = "version: , compiler: javac, environment: Java 21.0.2 (Amazon.com Inc.)"
+)
+public class SourceTargetMapperImpl implements SourceTargetMapper {
+
+    @Override
+    public Target sourceToTarget(Source source) {
+        if ( source == null ) {
+            return null;
+        }
+
+        Target target = new Target();
+
+        target.setI( new DecimalFormat( "##.00" ).format( source.getI() ) );
+        if ( source.getIi() != null ) {
+            target.setIi( new DecimalFormat( "##.00" ).format( source.getIi() ) );
+        }
+        target.setD( new DecimalFormat( "##.00" ).format( source.getD() ) );
+        if ( source.getDd() != null ) {
+            target.setDd( new DecimalFormat( "##.00" ).format( source.getDd() ) );
+        }
+        target.setF( new DecimalFormat( "##.00" ).format( source.getF() ) );
+        if ( source.getFf() != null ) {
+            target.setFf( new DecimalFormat( "##.00" ).format( source.getFf() ) );
+        }
+        target.setL( new DecimalFormat( "##.00" ).format( source.getL() ) );
+        if ( source.getLl() != null ) {
+            target.setLl( new DecimalFormat( "##.00" ).format( source.getLl() ) );
+        }
+        target.setB( new DecimalFormat( "##.00" ).format( source.getB() ) );
+        if ( source.getBb() != null ) {
+            target.setBb( new DecimalFormat( "##.00" ).format( source.getBb() ) );
+        }
+        target.setComplex1( new DecimalFormat( "##0.##E0" ).format( source.getComplex1() ) );
+        target.setComplex2( new DecimalFormat( "$#.00" ).format( source.getComplex2() ) );
+        if ( source.getBigDecimal1() != null ) {
+            target.setBigDecimal1( createDecimalFormat( "#0.#E0" ).format( source.getBigDecimal1() ) );
+        }
+        if ( source.getBigInteger1() != null ) {
+            target.setBigInteger1( createDecimalFormat( "0.#############E0" ).format( source.getBigInteger1() ) );
+        }
+
+        return target;
+    }
+
+    @Override
+    public Target sourceToTargetWithCustomLocale(Source source) {
+        if ( source == null ) {
+            return null;
+        }
+
+        Target target = new Target();
+
+        target.setI( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).format( source.getI() ) );
+        if ( source.getIi() != null ) {
+            target.setIi( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).format( source.getIi() ) );
+        }
+        target.setD( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).format( source.getD() ) );
+        if ( source.getDd() != null ) {
+            target.setDd( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).format( source.getDd() ) );
+        }
+        target.setF( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).format( source.getF() ) );
+        if ( source.getFf() != null ) {
+            target.setFf( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).format( source.getFf() ) );
+        }
+        target.setL( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).format( source.getL() ) );
+        if ( source.getLl() != null ) {
+            target.setLl( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).format( source.getLl() ) );
+        }
+        target.setB( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).format( source.getB() ) );
+        if ( source.getBb() != null ) {
+            target.setBb( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).format( source.getBb() ) );
+        }
+        target.setComplex1( new DecimalFormat( "##0.##E0", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).format( source.getComplex1() ) );
+        target.setComplex2( new DecimalFormat( "$#.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).format( source.getComplex2() ) );
+        if ( source.getBigDecimal1() != null ) {
+            target.setBigDecimal1( createDecimalFormatWithLocale( "#0.#E0", Locale.forLanguageTag( "ru" ) ).format( source.getBigDecimal1() ) );
+        }
+        if ( source.getBigInteger1() != null ) {
+            target.setBigInteger1( createDecimalFormatWithLocale( "0.#############E0", Locale.forLanguageTag( "ru" ) ).format( source.getBigInteger1() ) );
+        }
+
+        return target;
+    }
+
+    @Override
+    public Source targetToSource(Target target) {
+        if ( target == null ) {
+            return null;
+        }
+
+        Source source = new Source();
+
+        try {
+            if ( target.getI() != null ) {
+                source.setI( new DecimalFormat( "##.00" ).parse( target.getI() ).intValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getIi() != null ) {
+                source.setIi( new DecimalFormat( "##.00" ).parse( target.getIi() ).intValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getD() != null ) {
+                source.setD( new DecimalFormat( "##.00" ).parse( target.getD() ).doubleValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getDd() != null ) {
+                source.setDd( new DecimalFormat( "##.00" ).parse( target.getDd() ).doubleValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getF() != null ) {
+                source.setF( new DecimalFormat( "##.00" ).parse( target.getF() ).floatValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getFf() != null ) {
+                source.setFf( new DecimalFormat( "##.00" ).parse( target.getFf() ).floatValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getL() != null ) {
+                source.setL( new DecimalFormat( "##.00" ).parse( target.getL() ).longValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getLl() != null ) {
+                source.setLl( new DecimalFormat( "##.00" ).parse( target.getLl() ).longValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getB() != null ) {
+                source.setB( new DecimalFormat( "##.00" ).parse( target.getB() ).byteValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getBb() != null ) {
+                source.setBb( new DecimalFormat( "##.00" ).parse( target.getBb() ).byteValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getComplex1() != null ) {
+                source.setComplex1( new DecimalFormat( "##0.##E0" ).parse( target.getComplex1() ).doubleValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getComplex2() != null ) {
+                source.setComplex2( new DecimalFormat( "$#.00" ).parse( target.getComplex2() ).doubleValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getBigDecimal1() != null ) {
+                source.setBigDecimal1( (BigDecimal) createDecimalFormat( "#0.#E0" ).parse( target.getBigDecimal1() ) );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getBigInteger1() != null ) {
+                source.setBigInteger1( ( (BigDecimal) createDecimalFormat( "0.#############E0" ).parse( target.getBigInteger1() ) ).toBigInteger() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+
+        return source;
+    }
+
+    @Override
+    public Source targetToSourceWithCustomLocale(Target target) {
+        if ( target == null ) {
+            return null;
+        }
+
+        Source source = new Source();
+
+        try {
+            if ( target.getI() != null ) {
+                source.setI( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).parse( target.getI() ).intValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getIi() != null ) {
+                source.setIi( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).parse( target.getIi() ).intValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getD() != null ) {
+                source.setD( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).parse( target.getD() ).doubleValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getDd() != null ) {
+                source.setDd( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).parse( target.getDd() ).doubleValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getF() != null ) {
+                source.setF( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).parse( target.getF() ).floatValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getFf() != null ) {
+                source.setFf( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).parse( target.getFf() ).floatValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getL() != null ) {
+                source.setL( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).parse( target.getL() ).longValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getLl() != null ) {
+                source.setLl( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).parse( target.getLl() ).longValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getB() != null ) {
+                source.setB( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).parse( target.getB() ).byteValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getBb() != null ) {
+                source.setBb( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).parse( target.getBb() ).byteValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getComplex1() != null ) {
+                source.setComplex1( new DecimalFormat( "##0.##E0", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).parse( target.getComplex1() ).doubleValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getComplex2() != null ) {
+                source.setComplex2( new DecimalFormat( "$#.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).parse( target.getComplex2() ).doubleValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getBigDecimal1() != null ) {
+                source.setBigDecimal1( (BigDecimal) createDecimalFormatWithLocale( "#0.#E0", Locale.forLanguageTag( "ru" ) ).parse( target.getBigDecimal1() ) );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getBigInteger1() != null ) {
+                source.setBigInteger1( ( (BigDecimal) createDecimalFormatWithLocale( "0.#############E0", Locale.forLanguageTag( "ru" ) ).parse( target.getBigInteger1() ) ).toBigInteger() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+
+        return source;
+    }
+
+    @Override
+    public List<String> sourceToTarget(List<Float> source) {
+        if ( source == null ) {
+            return null;
+        }
+
+        List<String> list = new ArrayList<String>( source.size() );
+        for ( Float float1 : source ) {
+            list.add( new DecimalFormat( "##.00" ).format( float1 ) );
+        }
+
+        return list;
+    }
+
+    @Override
+    public List<Float> targetToSource(List<String> source) {
+        if ( source == null ) {
+            return null;
+        }
+
+        List<Float> list = new ArrayList<Float>( source.size() );
+        for ( String string : source ) {
+            try {
+                list.add( new DecimalFormat( "##.00" ).parse( string ).floatValue() );
+            }
+            catch ( ParseException e ) {
+                throw new RuntimeException( e );
+            }
+        }
+
+        return list;
+    }
+
+    @Override
+    public List<String> sourceToTargetWithCustomLocale(List<BigDecimal> source) {
+        if ( source == null ) {
+            return null;
+        }
+
+        List<String> list = new ArrayList<String>( source.size() );
+        for ( BigDecimal bigDecimal : source ) {
+            list.add( createDecimalFormatWithLocale( "#0.#E0", Locale.forLanguageTag( "fr" ) ).format( bigDecimal ) );
+        }
+
+        return list;
+    }
+
+    @Override
+    public List<BigDecimal> targetToSourceWithCustomLocale(List<String> source) {
+        if ( source == null ) {
+            return null;
+        }
+
+        List<BigDecimal> list = new ArrayList<BigDecimal>( source.size() );
+        for ( String string : source ) {
+            try {
+                list.add( (BigDecimal) createDecimalFormatWithLocale( "#0.#E0", Locale.forLanguageTag( "fr" ) ).parse( string ) );
+            }
+            catch ( ParseException e ) {
+                throw new RuntimeException( e );
+            }
+        }
+
+        return list;
+    }
+
+    @Override
+    public Map<String, String> sourceToTarget(Map<Float, Float> source) {
+        if ( source == null ) {
+            return null;
+        }
+
+        Map<String, String> map = LinkedHashMap.newLinkedHashMap( source.size() );
+
+        for ( java.util.Map.Entry<Float, Float> entry : source.entrySet() ) {
+            String key = new DecimalFormat( "##.00" ).format( entry.getKey() );
+            String value = new DecimalFormat( "##" ).format( entry.getValue() );
+            map.put( key, value );
+        }
+
+        return map;
+    }
+
+    @Override
+    public Map<String, String> sourceToTargetWithCustomLocale(Map<BigDecimal, BigDecimal> source) {
+        if ( source == null ) {
+            return null;
+        }
+
+        Map<String, String> map = LinkedHashMap.newLinkedHashMap( source.size() );
+
+        for ( java.util.Map.Entry<BigDecimal, BigDecimal> entry : source.entrySet() ) {
+            String key = createDecimalFormatWithLocale( "#0.#E0", Locale.forLanguageTag( "fr" ) ).format( entry.getKey() );
+            String value = createDecimalFormatWithLocale( "0.#############E0", Locale.forLanguageTag( "fr" ) ).format( entry.getValue() );
+            map.put( key, value );
+        }
+
+        return map;
+    }
+
+    @Override
+    public Map<Float, Float> targetToSource(Map<String, String> source) {
+        if ( source == null ) {
+            return null;
+        }
+
+        Map<Float, Float> map = LinkedHashMap.newLinkedHashMap( source.size() );
+
+        for ( java.util.Map.Entry<String, String> entry : source.entrySet() ) {
+            Float key;
+            try {
+                key = new DecimalFormat( "##.00" ).parse( entry.getKey() ).floatValue();
+            }
+            catch ( ParseException e ) {
+                throw new RuntimeException( e );
+            }
+            Float value;
+            try {
+                value = new DecimalFormat( "##" ).parse( entry.getValue() ).floatValue();
+            }
+            catch ( ParseException e ) {
+                throw new RuntimeException( e );
+            }
+            map.put( key, value );
+        }
+
+        return map;
+    }
+
+    @Override
+    public Map<BigDecimal, BigDecimal> targetToSourceWithCustomLocale(Map<String, String> source) {
+        if ( source == null ) {
+            return null;
+        }
+
+        Map<BigDecimal, BigDecimal> map = LinkedHashMap.newLinkedHashMap( source.size() );
+
+        for ( java.util.Map.Entry<String, String> entry : source.entrySet() ) {
+            BigDecimal key;
+            try {
+                key = (BigDecimal) createDecimalFormatWithLocale( "#0.#E0", Locale.forLanguageTag( "fr" ) ).parse( entry.getKey() );
+            }
+            catch ( ParseException e ) {
+                throw new RuntimeException( e );
+            }
+            BigDecimal value;
+            try {
+                value = (BigDecimal) createDecimalFormatWithLocale( "0.#############E0", Locale.forLanguageTag( "fr" ) ).parse( entry.getValue() );
+            }
+            catch ( ParseException e ) {
+                throw new RuntimeException( e );
+            }
+            map.put( key, value );
+        }
+
+        return map;
+    }
+
+    private DecimalFormat createDecimalFormatWithLocale( String numberFormat, Locale locale ) {
+
+        DecimalFormat df = new DecimalFormat( numberFormat, DecimalFormatSymbols.getInstance( locale ) );
+        df.setParseBigDecimal( true );
+        return df;
+    }
+
+    private DecimalFormat createDecimalFormat( String numberFormat ) {
+
+        DecimalFormat df = new DecimalFormat( numberFormat );
+        df.setParseBigDecimal( true );
+        return df;
+    }
+}

processor/src/test/resources/fixtures/org/mapstruct/ap/test/conversion/numbers/SourceTargetMapperImpl.java

@@ -0,0 +1,525 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.test.conversion.numbers;
+
+import java.math.BigDecimal;
+import java.text.DecimalFormat;
+import java.text.DecimalFormatSymbols;
+import java.text.ParseException;
+import java.util.ArrayList;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+import javax.annotation.processing.Generated;
+
+@Generated(
+    value = "org.mapstruct.ap.MappingProcessor",
+    date = "2024-09-14T11:36:20+0300",
+    comments = "version: , compiler: javac, environment: Java 17.0.10 (Private Build)"
+)
+public class SourceTargetMapperImpl implements SourceTargetMapper {
+
+    @Override
+    public Target sourceToTarget(Source source) {
+        if ( source == null ) {
+            return null;
+        }
+
+        Target target = new Target();
+
+        target.setI( new DecimalFormat( "##.00" ).format( source.getI() ) );
+        if ( source.getIi() != null ) {
+            target.setIi( new DecimalFormat( "##.00" ).format( source.getIi() ) );
+        }
+        target.setD( new DecimalFormat( "##.00" ).format( source.getD() ) );
+        if ( source.getDd() != null ) {
+            target.setDd( new DecimalFormat( "##.00" ).format( source.getDd() ) );
+        }
+        target.setF( new DecimalFormat( "##.00" ).format( source.getF() ) );
+        if ( source.getFf() != null ) {
+            target.setFf( new DecimalFormat( "##.00" ).format( source.getFf() ) );
+        }
+        target.setL( new DecimalFormat( "##.00" ).format( source.getL() ) );
+        if ( source.getLl() != null ) {
+            target.setLl( new DecimalFormat( "##.00" ).format( source.getLl() ) );
+        }
+        target.setB( new DecimalFormat( "##.00" ).format( source.getB() ) );
+        if ( source.getBb() != null ) {
+            target.setBb( new DecimalFormat( "##.00" ).format( source.getBb() ) );
+        }
+        target.setComplex1( new DecimalFormat( "##0.##E0" ).format( source.getComplex1() ) );
+        target.setComplex2( new DecimalFormat( "$#.00" ).format( source.getComplex2() ) );
+        if ( source.getBigDecimal1() != null ) {
+            target.setBigDecimal1( createDecimalFormat( "#0.#E0" ).format( source.getBigDecimal1() ) );
+        }
+        if ( source.getBigInteger1() != null ) {
+            target.setBigInteger1( createDecimalFormat( "0.#############E0" ).format( source.getBigInteger1() ) );
+        }
+
+        return target;
+    }
+
+    @Override
+    public Target sourceToTargetWithCustomLocale(Source source) {
+        if ( source == null ) {
+            return null;
+        }
+
+        Target target = new Target();
+
+        target.setI( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).format( source.getI() ) );
+        if ( source.getIi() != null ) {
+            target.setIi( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).format( source.getIi() ) );
+        }
+        target.setD( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).format( source.getD() ) );
+        if ( source.getDd() != null ) {
+            target.setDd( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).format( source.getDd() ) );
+        }
+        target.setF( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).format( source.getF() ) );
+        if ( source.getFf() != null ) {
+            target.setFf( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).format( source.getFf() ) );
+        }
+        target.setL( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).format( source.getL() ) );
+        if ( source.getLl() != null ) {
+            target.setLl( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).format( source.getLl() ) );
+        }
+        target.setB( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).format( source.getB() ) );
+        if ( source.getBb() != null ) {
+            target.setBb( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).format( source.getBb() ) );
+        }
+        target.setComplex1( new DecimalFormat( "##0.##E0", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).format( source.getComplex1() ) );
+        target.setComplex2( new DecimalFormat( "$#.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).format( source.getComplex2() ) );
+        if ( source.getBigDecimal1() != null ) {
+            target.setBigDecimal1( createDecimalFormatWithLocale( "#0.#E0", Locale.forLanguageTag( "ru" ) ).format( source.getBigDecimal1() ) );
+        }
+        if ( source.getBigInteger1() != null ) {
+            target.setBigInteger1( createDecimalFormatWithLocale( "0.#############E0", Locale.forLanguageTag( "ru" ) ).format( source.getBigInteger1() ) );
+        }
+
+        return target;
+    }
+
+    @Override
+    public Source targetToSource(Target target) {
+        if ( target == null ) {
+            return null;
+        }
+
+        Source source = new Source();
+
+        try {
+            if ( target.getI() != null ) {
+                source.setI( new DecimalFormat( "##.00" ).parse( target.getI() ).intValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getIi() != null ) {
+                source.setIi( new DecimalFormat( "##.00" ).parse( target.getIi() ).intValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getD() != null ) {
+                source.setD( new DecimalFormat( "##.00" ).parse( target.getD() ).doubleValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getDd() != null ) {
+                source.setDd( new DecimalFormat( "##.00" ).parse( target.getDd() ).doubleValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getF() != null ) {
+                source.setF( new DecimalFormat( "##.00" ).parse( target.getF() ).floatValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getFf() != null ) {
+                source.setFf( new DecimalFormat( "##.00" ).parse( target.getFf() ).floatValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getL() != null ) {
+                source.setL( new DecimalFormat( "##.00" ).parse( target.getL() ).longValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getLl() != null ) {
+                source.setLl( new DecimalFormat( "##.00" ).parse( target.getLl() ).longValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getB() != null ) {
+                source.setB( new DecimalFormat( "##.00" ).parse( target.getB() ).byteValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getBb() != null ) {
+                source.setBb( new DecimalFormat( "##.00" ).parse( target.getBb() ).byteValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getComplex1() != null ) {
+                source.setComplex1( new DecimalFormat( "##0.##E0" ).parse( target.getComplex1() ).doubleValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getComplex2() != null ) {
+                source.setComplex2( new DecimalFormat( "$#.00" ).parse( target.getComplex2() ).doubleValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getBigDecimal1() != null ) {
+                source.setBigDecimal1( (BigDecimal) createDecimalFormat( "#0.#E0" ).parse( target.getBigDecimal1() ) );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getBigInteger1() != null ) {
+                source.setBigInteger1( ( (BigDecimal) createDecimalFormat( "0.#############E0" ).parse( target.getBigInteger1() ) ).toBigInteger() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+
+        return source;
+    }
+
+    @Override
+    public Source targetToSourceWithCustomLocale(Target target) {
+        if ( target == null ) {
+            return null;
+        }
+
+        Source source = new Source();
+
+        try {
+            if ( target.getI() != null ) {
+                source.setI( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).parse( target.getI() ).intValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getIi() != null ) {
+                source.setIi( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).parse( target.getIi() ).intValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getD() != null ) {
+                source.setD( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).parse( target.getD() ).doubleValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getDd() != null ) {
+                source.setDd( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).parse( target.getDd() ).doubleValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getF() != null ) {
+                source.setF( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).parse( target.getF() ).floatValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getFf() != null ) {
+                source.setFf( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).parse( target.getFf() ).floatValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getL() != null ) {
+                source.setL( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).parse( target.getL() ).longValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getLl() != null ) {
+                source.setLl( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).parse( target.getLl() ).longValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getB() != null ) {
+                source.setB( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).parse( target.getB() ).byteValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getBb() != null ) {
+                source.setBb( new DecimalFormat( "##.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).parse( target.getBb() ).byteValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getComplex1() != null ) {
+                source.setComplex1( new DecimalFormat( "##0.##E0", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).parse( target.getComplex1() ).doubleValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getComplex2() != null ) {
+                source.setComplex2( new DecimalFormat( "$#.00", DecimalFormatSymbols.getInstance( Locale.forLanguageTag( "ru " ) ) ).parse( target.getComplex2() ).doubleValue() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getBigDecimal1() != null ) {
+                source.setBigDecimal1( (BigDecimal) createDecimalFormatWithLocale( "#0.#E0", Locale.forLanguageTag( "ru" ) ).parse( target.getBigDecimal1() ) );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+        try {
+            if ( target.getBigInteger1() != null ) {
+                source.setBigInteger1( ( (BigDecimal) createDecimalFormatWithLocale( "0.#############E0", Locale.forLanguageTag( "ru" ) ).parse( target.getBigInteger1() ) ).toBigInteger() );
+            }
+        }
+        catch ( ParseException e ) {
+            throw new RuntimeException( e );
+        }
+
+        return source;
+    }
+
+    @Override
+    public List<String> sourceToTarget(List<Float> source) {
+        if ( source == null ) {
+            return null;
+        }
+
+        List<String> list = new ArrayList<String>( source.size() );
+        for ( Float float1 : source ) {
+            list.add( new DecimalFormat( "##.00" ).format( float1 ) );
+        }
+
+        return list;
+    }
+
+    @Override
+    public List<Float> targetToSource(List<String> source) {
+        if ( source == null ) {
+            return null;
+        }
+
+        List<Float> list = new ArrayList<Float>( source.size() );
+        for ( String string : source ) {
+            try {
+                list.add( new DecimalFormat( "##.00" ).parse( string ).floatValue() );
+            }
+            catch ( ParseException e ) {
+                throw new RuntimeException( e );
+            }
+        }
+
+        return list;
+    }
+
+    @Override
+    public List<String> sourceToTargetWithCustomLocale(List<BigDecimal> source) {
+        if ( source == null ) {
+            return null;
+        }
+
+        List<String> list = new ArrayList<String>( source.size() );
+        for ( BigDecimal bigDecimal : source ) {
+            list.add( createDecimalFormatWithLocale( "#0.#E0", Locale.forLanguageTag( "fr" ) ).format( bigDecimal ) );
+        }
+
+        return list;
+    }
+
+    @Override
+    public List<BigDecimal> targetToSourceWithCustomLocale(List<String> source) {
+        if ( source == null ) {
+            return null;
+        }
+
+        List<BigDecimal> list = new ArrayList<BigDecimal>( source.size() );
+        for ( String string : source ) {
+            try {
+                list.add( (BigDecimal) createDecimalFormatWithLocale( "#0.#E0", Locale.forLanguageTag( "fr" ) ).parse( string ) );
+            }
+            catch ( ParseException e ) {
+                throw new RuntimeException( e );
+            }
+        }
+
+        return list;
+    }
+
+    @Override
+    public Map<String, String> sourceToTarget(Map<Float, Float> source) {
+        if ( source == null ) {
+            return null;
+        }
+
+        Map<String, String> map = new LinkedHashMap<String, String>( Math.max( (int) ( source.size() / .75f ) + 1, 16 ) );
+
+        for ( java.util.Map.Entry<Float, Float> entry : source.entrySet() ) {
+            String key = new DecimalFormat( "##.00" ).format( entry.getKey() );
+            String value = new DecimalFormat( "##" ).format( entry.getValue() );
+            map.put( key, value );
+        }
+
+        return map;
+    }
+
+    @Override
+    public Map<String, String> sourceToTargetWithCustomLocale(Map<BigDecimal, BigDecimal> source) {
+        if ( source == null ) {
+            return null;
+        }
+
+        Map<String, String> map = new LinkedHashMap<String, String>( Math.max( (int) ( source.size() / .75f ) + 1, 16 ) );
+
+        for ( java.util.Map.Entry<BigDecimal, BigDecimal> entry : source.entrySet() ) {
+            String key = createDecimalFormatWithLocale( "#0.#E0", Locale.forLanguageTag( "fr" ) ).format( entry.getKey() );
+            String value = createDecimalFormatWithLocale( "0.#############E0", Locale.forLanguageTag( "fr" ) ).format( entry.getValue() );
+            map.put( key, value );
+        }
+
+        return map;
+    }
+
+    @Override
+    public Map<Float, Float> targetToSource(Map<String, String> source) {
+        if ( source == null ) {
+            return null;
+        }
+
+        Map<Float, Float> map = new LinkedHashMap<Float, Float>( Math.max( (int) ( source.size() / .75f ) + 1, 16 ) );
+
+        for ( java.util.Map.Entry<String, String> entry : source.entrySet() ) {
+            Float key;
+            try {
+                key = new DecimalFormat( "##.00" ).parse( entry.getKey() ).floatValue();
+            }
+            catch ( ParseException e ) {
+                throw new RuntimeException( e );
+            }
+            Float value;
+            try {
+                value = new DecimalFormat( "##" ).parse( entry.getValue() ).floatValue();
+            }
+            catch ( ParseException e ) {
+                throw new RuntimeException( e );
+            }
+            map.put( key, value );
+        }
+
+        return map;
+    }
+
+    @Override
+    public Map<BigDecimal, BigDecimal> targetToSourceWithCustomLocale(Map<String, String> source) {
+        if ( source == null ) {
+            return null;
+        }
+
+        Map<BigDecimal, BigDecimal> map = new LinkedHashMap<BigDecimal, BigDecimal>( Math.max( (int) ( source.size() / .75f ) + 1, 16 ) );
+
+        for ( java.util.Map.Entry<String, String> entry : source.entrySet() ) {
+            BigDecimal key;
+            try {
+                key = (BigDecimal) createDecimalFormatWithLocale( "#0.#E0", Locale.forLanguageTag( "fr" ) ).parse( entry.getKey() );
+            }
+            catch ( ParseException e ) {
+                throw new RuntimeException( e );
+            }
+            BigDecimal value;
+            try {
+                value = (BigDecimal) createDecimalFormatWithLocale( "0.#############E0", Locale.forLanguageTag( "fr" ) ).parse( entry.getValue() );
+            }
+            catch ( ParseException e ) {
+                throw new RuntimeException( e );
+            }
+            map.put( key, value );
+        }
+
+        return map;
+    }
+
+    private DecimalFormat createDecimalFormatWithLocale( String numberFormat, Locale locale ) {
+
+        DecimalFormat df = new DecimalFormat( numberFormat, DecimalFormatSymbols.getInstance( locale ) );
+        df.setParseBigDecimal( true );
+        return df;
+    }
+
+    private DecimalFormat createDecimalFormat( String numberFormat ) {
+
+        DecimalFormat df = new DecimalFormat( numberFormat );
+        df.setParseBigDecimal( true );
+        return df;
+    }
+}