polish

org.springframework.context/src/main/java/org/springframework/mapping/support/DefaultMappingTargetFactory.java

@@ -30,7 +30,7 @@ final class DefaultMappingTargetFactory implements MappingTargetFactory {
 		return ClassUtils.hasConstructor(targetType.getType(), null);
 	}
 
-	public Object createTarget(TypeDescriptor targetType) {
+	public Object createTarget(Object source, TypeDescriptor sourceType, TypeDescriptor targetType) {
 		return BeanUtils.instantiate(targetType.getType());
 	}
 

org.springframework.context/src/main/java/org/springframework/mapping/support/MappingContextHolder.java

@@ -24,7 +24,7 @@ import org.springframework.core.NamedThreadLocal;
  * @author Keith Donald
  * @see SpelMapper#map(Object, Object)
  */
-abstract class MappingContextHolder {
+public abstract class MappingContextHolder {
 
 	private static final ThreadLocal<Stack<Object>> mappingContextHolder = new NamedThreadLocal<Stack<Object>>(
 			"Mapping context");

org.springframework.context/src/main/java/org/springframework/mapping/support/MappingConverter.java

@@ -33,10 +33,20 @@ public final class MappingConverter implements GenericConverter {
 
 	private MappingTargetFactory mappingTargetFactory;
 
+	/**
+	 * Creates a new Converter that delegates to the mapper to complete the type conversion process.
+	 * Uses a {@link DefaultMappingTargetFactory} to create the target object to map and return.
+	 * @param mapper the mapper
+	 */
 	public MappingConverter(Mapper mapper) {
 		this(mapper, new DefaultMappingTargetFactory());
 	}
 
+	/**
+	 * Creates a new Converter that delegates to the mapper to complete the type conversion process.
+	 * Uses the specified MappingTargetFactory to create the target object to map and return.
+	 * @param mapper the mapper
+	 */
 	public MappingConverter(Mapper mapper, MappingTargetFactory mappingTargetFactory) {
 		this.mapper = mapper;
 		this.mappingTargetFactory = mappingTargetFactory;
@@ -52,7 +62,7 @@ public final class MappingConverter implements GenericConverter {
 		if (sourceType.isAssignableTo(targetType) && isCopyByReference(sourceType, targetType)) {
 			return source;
 		}
-		return createAndMap(targetType, source, sourceType);
+		return createTargetAndMap(source, sourceType, targetType);
 	}
 
 	private boolean isCopyByReference(TypeDescriptor sourceType, TypeDescriptor targetType) {
@@ -63,13 +73,13 @@ public final class MappingConverter implements GenericConverter {
 		}
 	}
 
-	private Object createAndMap(TypeDescriptor targetType, Object source, TypeDescriptor sourceType) {
+	private Object createTargetAndMap(Object source, TypeDescriptor sourceType, TypeDescriptor targetType) {
 		if (this.mappingTargetFactory.supports(targetType)) {
-			Object target = this.mappingTargetFactory.createTarget(targetType);
+			Object target = this.mappingTargetFactory.createTarget(source, sourceType, targetType);
 			return this.mapper.map(source, target);
 		} else {
 			IllegalStateException cause = new IllegalStateException("["
-					+ this.mappingTargetFactory.getClass().getName() + "] does not support target type ["
+					+ this.mappingTargetFactory.getClass().getName() + "] does not support targetType ["
 					+ targetType.getName() + "]");
 			throw new ConversionFailedException(sourceType, targetType, source, cause);
 		}

org.springframework.context/src/main/java/org/springframework/mapping/support/MappingTargetFactory.java

@@ -41,6 +41,6 @@ public interface MappingTargetFactory {
 	 * @param targetType the target object type descriptor
 	 * @return the target
 	 */
-	public Object createTarget(TypeDescriptor targetType);
+	public Object createTarget(Object source, TypeDescriptor sourceType, TypeDescriptor targetType);
 
 }

org.springframework.context/src/main/java/org/springframework/mapping/support/SpelMapper.java

@@ -170,7 +170,8 @@ public class SpelMapper implements Mapper<Object, Object> {
 	 */
 	public void addNestedMapper(Class<?> sourceType, Class<?> targetType, Mapper<?, ?> nestedMapper,
 			MappingTargetFactory targetFactory) {
-		this.conversionService.addGenericConverter(sourceType, targetType, new MappingConverter(nestedMapper));
+		this.conversionService.addGenericConverter(sourceType, targetType, new MappingConverter(nestedMapper,
+				targetFactory));
 	}
 
 	/**

org.springframework.context/src/test/java/org/springframework/mapping/support/SpelMapperTests.java

@@ -14,6 +14,7 @@ import java.util.Set;
 
 import org.junit.Test;
 import org.springframework.core.convert.ConversionService;
+import org.springframework.core.convert.TypeDescriptor;
 import org.springframework.core.convert.converter.Converter;
 import org.springframework.core.io.ClassPathResource;
 import org.springframework.expression.AccessException;
@@ -201,6 +202,41 @@ public class SpelMapperTests {
 		assertEquals("bar and baz", target.nested.foo);
 	}
 
+	@Test
+	public void mapBeanNestedCustomNestedMapperCustomMappingTargetFactory() {
+		PersonDto source = new PersonDto();
+		final NestedDto nested = new NestedDto();
+		nested.foo = "bar";
+		source.setNested(nested);
+
+		Person target = new Person();
+
+		SpelMapper nestedMapper = new SpelMapper();
+		nestedMapper.setAutoMappingEnabled(false);
+		nestedMapper.addMapping("foo").setConverter(new Converter<String, String>() {
+			public String convert(String source) {
+				return source + " and baz";
+			}
+		});
+		mapper.addNestedMapper(NestedDto.class, Nested.class, nestedMapper, new MappingTargetFactory() {
+			public boolean supports(TypeDescriptor targetType) {
+				return true;
+			}
+			
+			public Object createTarget(Object source, TypeDescriptor sourceType, TypeDescriptor targetType) {
+				NestedDto nestedDto = (NestedDto) source;
+				assertEquals(nested, nestedDto);
+				return new Nested();
+			}
+		});
+
+		mapper.setAutoMappingEnabled(false);
+		mapper.addMapping("nested");
+		mapper.map(source, target);
+
+		assertEquals("bar and baz", target.nested.foo);
+	}
+	
 	@Test
 	public void mapBeanNestedCustomNestedMapperHandCoded() {
 		PersonDto source = new PersonDto();
@@ -225,6 +261,37 @@ public class SpelMapperTests {
 
 		assertEquals("bar and baz", target.nested.foo);
 	}
+	
+	@Test
+	public void mapBeanNestedCustomConverterDelegatingToMapper() {
+		PersonDto source = new PersonDto();
+		NestedDto nested = new NestedDto();
+		nested.foo = "bar";
+		source.setNested(nested);
+
+		Person target = new Person();
+
+		mapper.getConverterRegistry().addConverter(new Converter<NestedDto, Nested>() {
+			public Nested convert(NestedDto source) {
+				// allows construction of target to be controlled by the converter
+				Nested nested = new Nested();
+				// mapping can do whatever, here we delegate to nested SpelMapper
+				SpelMapper nestedMapper = new SpelMapper();
+				nestedMapper.addMapping("foo").setConverter(new Converter<String, String>() {
+					public String convert(String source) {
+						return source + " and baz";
+					}
+				});
+				return (Nested) nestedMapper.map(source, nested);
+			}
+		});
+
+		mapper.setAutoMappingEnabled(false);
+		mapper.addMapping("nested");
+		mapper.map(source, target);
+
+		assertEquals("bar and baz", target.nested.foo);
+	}
 
 	@Test
 	public void mapList() {