mapstruct#597 Built-In conversion between String and StringBuilder

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

@@ -231,4 +231,15 @@ public final class ConversionUtils {
     public static String dateTimeFormat(ConversionContext conversionContext) {
         return typeReferenceName( conversionContext, JodaTimeConstants.DATE_TIME_FORMAT_FQN );
     }
+
+    /**
+     * Name for {@link java.lang.StringBuilder}.
+     *
+     * @param conversionContext Conversion context
+     *
+     * @return Name or fully-qualified name.
+     */
+    public static String stringBuilder(ConversionContext conversionContext) {
+        return typeReferenceName( conversionContext, StringBuilder.class );
+    }
 }

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

@@ -175,6 +175,7 @@ public class Conversions {
         register( Character.class, String.class, new CharWrapperToStringConversion() );
         register( BigInteger.class, String.class, new BigIntegerToStringConversion() );
         register( BigDecimal.class, String.class, new BigDecimalToStringConversion() );
+        register( StringBuilder.class, String.class, new StringBuilderToStringConversion() );
 
         registerJodaConversions();
 

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

@@ -0,0 +1,25 @@
+/*
+ * 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.internal.conversion;
+
+import org.mapstruct.ap.internal.model.common.ConversionContext;
+
+/**
+ * Handles conversion between a target type {@link StringBuilder} and {@link String}.
+ *
+ */
+public class StringBuilderToStringConversion extends SimpleConversion {
+
+    @Override
+    protected String getToExpression(ConversionContext conversionContext) {
+        return "<SOURCE>.toString()";
+    }
+
+    @Override
+    protected String getFromExpression(ConversionContext conversionContext) {
+        return "new " + ConversionUtils.stringBuilder( conversionContext ) + "( <SOURCE> )";
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/conversion/string/Source.java

@@ -23,6 +23,7 @@ public class Source {
     private Boolean boolBool;
     private char c;
     private Character cc;
+    private StringBuilder sb;
     private Object object;
 
     public byte getB() {
@@ -160,4 +161,12 @@ public class Source {
     public void setObject(Object object) {
         this.object = object;
     }
+
+    public StringBuilder getSb() {
+        return sb;
+    }
+
+    public void setSb(StringBuilder sb) {
+        this.sb = sb;
+    }
 }

processor/src/test/java/org/mapstruct/ap/test/conversion/string/StringConversionTest.java

@@ -48,6 +48,7 @@ public class StringConversionTest {
         source.setBoolBool( Boolean.TRUE );
         source.setC( 'G' );
         source.setCc( 'H' );
+        source.setSb( new StringBuilder( "SB" ) );
 
         Target target = SourceTargetMapper.INSTANCE.sourceToTarget( source );
 
@@ -68,6 +69,7 @@ public class StringConversionTest {
         assertThat( target.getBoolBool() ).isEqualTo( "true" );
         assertThat( target.getC() ).isEqualTo( "G" );
         assertThat( target.getCc() ).isEqualTo( "H" );
+        assertThat( target.getSb() ).isEqualTo( "SB" );
     }
 
     @Test
@@ -89,6 +91,7 @@ public class StringConversionTest {
         target.setBoolBool( "true" );
         target.setC( "G" );
         target.setCc( "H" );
+        target.setSb( "SB" );
 
         Source source = SourceTargetMapper.INSTANCE.targetToSource( target );
 
@@ -109,6 +112,7 @@ public class StringConversionTest {
         assertThat( source.getBoolBool() ).isEqualTo( true );
         assertThat( source.getC() ).isEqualTo( 'G' );
         assertThat( source.getCc() ).isEqualTo( 'H' );
+        assertThat( source.getSb().toString() ).isEqualTo( "SB" );
     }
 
     @Test

processor/src/test/java/org/mapstruct/ap/test/conversion/string/Target.java

@@ -23,6 +23,7 @@ public class Target {
     private String boolBool;
     private String c;
     private String cc;
+    private String sb;
     private String object;
 
     public String getB() {
@@ -160,4 +161,12 @@ public class Target {
     public void setObject(String object) {
         this.object = object;
     }
+
+    public String getSb() {
+        return sb;
+    }
+
+    public void setSb(String sb) {
+        this.sb = sb;
+    }
 }

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

@@ -9,8 +9,8 @@ import javax.annotation.Generated;
 
 @Generated(
     value = "org.mapstruct.ap.MappingProcessor",
-    date = "2016-12-30T19:22:52+0100",
+    date = "2020-10-24T17:41:29+0300",
-    comments = "version: , compiler: javac, environment: Java 1.8.0_112 (Oracle Corporation)"
+    comments = "version: , compiler: javac, environment: Java 1.8.0_265 (AdoptOpenJDK)"
 )
 public class SourceTargetMapperImpl implements SourceTargetMapper {
 
@@ -54,6 +54,9 @@ public class SourceTargetMapperImpl implements SourceTargetMapper {
         if ( source.getCc() != null ) {
             target.setCc( source.getCc().toString() );
         }
+        if ( source.getSb() != null ) {
+            target.setSb( source.getSb().toString() );
+        }
 
         return target;
     }
@@ -115,6 +118,9 @@ public class SourceTargetMapperImpl implements SourceTargetMapper {
             source.setCc( target.getCc().charAt( 0 ) );
         }
         source.setObject( target.getObject() );
+        if ( target.getSb() != null ) {
+            source.setSb( new StringBuilder( target.getSb() ) );
+        }
 
         return source;
     }