#2552 Add built in conversion between URL and String

documentation/src/main/asciidoc/chapter-5-data-type-conversions.asciidoc

@@ -122,6 +122,9 @@ public interface CarMapper {
 
 * Between `String` and `StringBuilder`
 
+* Between `java.net.URL` and `String`.
+** When converting from a `String`, the value needs to be a valid https://en.wikipedia.org/wiki/URL[URL] otherwise a `MalformedURLException` is thrown.
+
 [[mapping-object-references]]
 === Mapping object references
 

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

@@ -7,6 +7,7 @@ package org.mapstruct.ap.internal.conversion;
 
 import java.math.BigDecimal;
 import java.math.BigInteger;
+import java.net.URL;
 import java.sql.Time;
 import java.sql.Timestamp;
 import java.text.DecimalFormat;
@@ -254,4 +255,15 @@ public final class ConversionUtils {
     public static String uuid(ConversionContext conversionContext) {
         return typeReferenceName( conversionContext, UUID.class );
     }
+
+    /**
+     * Name for {@link java.net.URL}.
+     *
+     * @param conversionContext Conversion context
+     *
+     * @return Name or fully-qualified name.
+     */
+    public static String url(ConversionContext conversionContext) {
+        return typeReferenceName( conversionContext, URL.class );
+    }
 }

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

@@ -7,6 +7,7 @@ package org.mapstruct.ap.internal.conversion;
 
 import java.math.BigDecimal;
 import java.math.BigInteger;
+import java.net.URL;
 import java.sql.Time;
 import java.sql.Timestamp;
 import java.time.Duration;
@@ -193,6 +194,8 @@ public class Conversions {
         register( Currency.class, String.class, new CurrencyToStringConversion() );
 
         register( UUID.class, String.class, new UUIDToStringConversion() );
+
+        registerURLConversion();
     }
 
     private void registerJodaConversions() {
@@ -294,6 +297,16 @@ public class Conversions {
         }
     }
 
+    private void registerURLConversion() {
+        if ( isJavaURLAvailable() ) {
+            register( URL.class, String.class, new URLToStringConversion() );
+        }
+    }
+
+    private boolean isJavaURLAvailable() {
+        return typeFactory.isTypeAvailable( "java.net.URL" );
+    }
+
     private void register(Class<?> sourceClass, Class<?> targetClass, ConversionProvider conversion) {
         Type sourceType = typeFactory.getType( sourceClass );
         Type targetType = typeFactory.getType( targetClass );

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

@@ -0,0 +1,46 @@
+/*
+ * 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;
+import org.mapstruct.ap.internal.model.common.Type;
+
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.util.List;
+import java.util.Set;
+
+import static org.mapstruct.ap.internal.conversion.ConversionUtils.url;
+import static org.mapstruct.ap.internal.util.Collections.asSet;
+
+/**
+ * Conversion between {@link java.net.URL} and {@link String}.
+ *
+ * @author Adam Szatyin
+ */
+public class URLToStringConversion extends SimpleConversion {
+    @Override
+    protected String getToExpression(ConversionContext conversionContext) {
+        return "<SOURCE>.toString()";
+    }
+
+    @Override
+    protected String getFromExpression(ConversionContext conversionContext) {
+        return "new " + url( conversionContext ) + "( <SOURCE> )";
+    }
+
+    @Override
+    protected Set<Type> getFromConversionImportTypes(final ConversionContext conversionContext) {
+        return asSet( conversionContext.getTypeFactory().getType( URL.class ) );
+    }
+
+    @Override
+    protected List<Type> getFromConversionExceptionTypes(ConversionContext conversionContext) {
+        return java.util.Collections.singletonList(
+                conversionContext.getTypeFactory().getType( MalformedURLException.class )
+        );
+    }
+}

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

@@ -0,0 +1,33 @@
+/*
+ * 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.url;
+
+import java.net.URL;
+
+/**
+ * @author Adam Szatyin
+ */
+public class Source {
+    private URL url;
+
+    private URL invalidURL;
+
+    public URL getURL() {
+        return url;
+    }
+
+    public void setURL(URL url) {
+        this.url = url;
+    }
+
+    public URL getInvalidURL() {
+        return invalidURL;
+    }
+
+    public void setInvalidURL(URL invalidURL) {
+        this.invalidURL = invalidURL;
+    }
+}

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

@@ -0,0 +1,30 @@
+/*
+ * 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.url;
+
+/**
+ * @author Adam Szatyin
+ */
+public class Target {
+    private String url;
+    private String invalidURL;
+
+    public String getURL() {
+        return this.url;
+    }
+
+    public void setURL(final String url) {
+        this.url = url;
+    }
+
+    public String getInvalidURL() {
+        return this.invalidURL;
+    }
+
+    public void setInvalidURL(final String invalidURL) {
+        this.invalidURL = invalidURL;
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/conversion/url/URLConversionTest.java

@@ -0,0 +1,76 @@
+/*
+ * 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.url;
+
+import org.mapstruct.ap.testutil.ProcessorTest;
+import org.mapstruct.ap.testutil.WithClasses;
+
+import java.net.MalformedURLException;
+import java.net.URL;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+/**
+ * Tests conversions between {@link java.net.URL} and String.
+ *
+ * @author Adam Szatyin
+ */
+@WithClasses({ Source.class, Target.class, URLMapper.class })
+public class URLConversionTest {
+
+    @ProcessorTest
+    public void shouldApplyURLConversion() throws MalformedURLException {
+        Source source = new Source();
+        source.setURL( new URL("https://mapstruct.org/") );
+
+        Target target = URLMapper.INSTANCE.sourceToTarget( source );
+
+        assertThat( target ).isNotNull();
+        assertThat( target.getURL() ).isEqualTo( source.getURL().toString() );
+    }
+
+    @ProcessorTest
+    public void shouldApplyReverseURLConversion() throws MalformedURLException {
+        Target target = new Target();
+        target.setURL( "https://mapstruct.org/" );
+
+        Source source = URLMapper.INSTANCE.targetToSource( target );
+
+        assertThat( source ).isNotNull();
+        assertThat( source.getURL() ).isEqualTo( new URL( target.getURL() ) );
+    }
+
+    @ProcessorTest
+    public void shouldHandleInvalidURLString() {
+        Target target = new Target();
+        target.setInvalidURL( "XXXXXXXXX" );
+
+        assertThatThrownBy( () -> URLMapper.INSTANCE.targetToSource( target ) )
+                .isInstanceOf( RuntimeException.class )
+                .getRootCause().isInstanceOf( MalformedURLException.class );
+    }
+
+    @ProcessorTest
+    public void shouldHandleInvalidURLStringWithMalformedURLException() {
+        Target target = new Target();
+        target.setInvalidURL( "XXXXXXXXX" );
+
+        assertThatThrownBy( () -> URLMapper.INSTANCE.targetToSourceWithMalformedURLException( target ) )
+                .isInstanceOf( MalformedURLException.class );
+    }
+
+    @ProcessorTest
+    public void shouldHandleNullURLString() {
+        Source source = new Source();
+
+        Target target = URLMapper.INSTANCE.sourceToTarget( source );
+
+        assertThat( target ).isNotNull();
+        assertThat( target.getURL() ).isNull();
+        assertThat( target.getInvalidURL() ).isNull();
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/conversion/url/URLMapper.java

@@ -0,0 +1,23 @@
+/*
+ * 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.url;
+
+import org.mapstruct.Mapper;
+import org.mapstruct.factory.Mappers;
+
+import java.net.MalformedURLException;
+
+@Mapper
+public interface URLMapper {
+
+    URLMapper INSTANCE = Mappers.getMapper( URLMapper.class );
+
+    Target sourceToTarget(Source source);
+
+    Source targetToSource(Target target);
+
+    Source targetToSourceWithMalformedURLException(Target target) throws MalformedURLException;
+}