Question

我们正在映射一个对象，该对象具有全部实现父接口但可能具有不同实现的对象列表。但是，当我们映射列表时，似乎仅映射了ParentClass的值，而不映射了子级的值。但是直接映射子项是可行的。

public class ParentClass{
String name;
int anotherParentField;
List<ParentClass> relation;
}

public class ChildClass1 extends ParentClass{
String customCLass1Field;
}

public class ChildClass2 extends ParentClass {
int intField;
}


public class ParentClassDto{
String name;
int anotherParentField;
List<ParentClassDto> relation;
}

public class ChildClass1Dto extends ParentClassDto{
String customCLass1Field;
}

public class ChildClass2Dto extends ParentClassDto {
int intField;
}

地图绘制者

@Mapper
public interface ParentClassMapper{
    ParentClassDto convertToDto(ParentClass p);
    ParentClass convertDTOToModel(ParentClassDto dto);
}


@Mapper
public interface ChildClass1Mapper implements ParentClassMapper
{
    ChildClass1Dto convertToDto(ChildClass1 p);
    ChildClass1 convertDTOToModel(ChildClass1Dto dto);
}

@Mapper
public interface ChildClass2Mapper implements ParentClassMapper
{
    ChildClass2Dto convertToDto(ChildClass2 p);
    ChildClass2 convertDTOToModel(ChildClass2Dto dto);
}

与此同时，如果我们在列表中映射包含ChildClass2和ChildClass1的对象ChildClass1，则会得到。

要映射的对象：子对象ChildClass1的json格式如下：

{
   "name":"myName",
   "anotherParentField":"10",
   "customCLass1Field":"custom name",
   "relation":[
      {
         (This is of Object Type : ChildClass1)
         "name":"firstRelationName",
         "anotherParentField":"110",
         "customCLass1Field":"relationcustom name"
      },
      {
         (This is of Object Type : ChildClass2)
         "name":"secondRelationName",
         "anotherParentField":"110",
         "intField":"4"
      }
   ]
}

但是当我们使用上面的映射器映射到dto时，我们得到：

{
   "name":"myName",
   "anotherParentField":"10",
   "customCLass1Field":"custom name",
   "relation":[
      {
         "name":"firstRelationName",
         "anotherParentField":"110",
      },
      {
         "name":"secondRelationName",
         "anotherParentField":"110",
      }
   ]
}

子类的任何字段均未映射。缺少什么？

Answer 1

除了自定义映射器之外，我看不到其他方法。

这是我所说的decorator的解决方案：

public abstract class ParentClassMapperDecorator implements ParentClassMapper {

  private final ParentClassMapper delegate;

  public ParentClassMapperDecorator(ParentClassMapper delegate) {
    this.delegate = delegate;
  }

  @Override
  public ParentClass convertDTOToModel(ParentClassDto dto) {
    ParentClass parentClass = null;

    if (dto instanceof ChildClass1Dto) {
      parentClass = Mappers.getMapper(ChildClass1Mapper.class).convertDTOToModel((ChildClass1Dto) dto);
    } else if (dto instanceof ChildClass2Dto) {
      parentClass = Mappers.getMapper(ChildClass2Mapper.class).convertDTOToModel((ChildClass2Dto) dto);
    } else {
      parentClass = this.delegate.convertDTOToModel(dto);
    }

    return parentClass;
  }

  @Override
  public ParentClassDto convertToDto(ParentClass p) {
    // Do the job here
  }
}

然后在ParentClassMapper中添加@DecoratedWith批注：

@Mapper
@DecoratedWith(ParentClassMapperDecorator.class)
public interface ParentClassMapper {

  ParentClassDto convertToDto(ParentClass p);

  ParentClass convertDTOToModel(ParentClassDto dto);
}

对于孩子：

@Mapper(uses = {ParentClassMapper.class})
public interface ChildClass1Mapper{

  ChildClass1Dto convertToDto(ChildClass1 p);

  ChildClass1 convertDTOToModel(ChildClass1Dto dto);
}

@Mapper(uses = {ParentClassMapper.class})
public interface ChildClass2Mapper {

  ChildClass2Dto convertToDto(ChildClass2 p);

  ChildClass2 convertDTOToModel(ChildClass2Dto dto);
}

如果要测试：

@Test
  public void mapStruct_Inheritance_Test() throws Exception {

    ChildClass1Dto childClass1Dto = new ChildClass1Dto();
    childClass1Dto.name = "name1";
    childClass1Dto.anotherParentField = 1;
    childClass1Dto.customCLass1Field = "customCLass1Field1";

    List<ParentClassDto> parentClassDtos = new ArrayList<>();
    ChildClass1Dto childClass11Dto = new ChildClass1Dto();
    childClass11Dto.name = "name12";
    childClass11Dto.anotherParentField = 12;
    childClass11Dto.customCLass1Field = "customCLass1Field12";
    parentClassDtos.add(childClass11Dto);

    ChildClass2Dto childClass21Dto = new ChildClass2Dto();
    childClass21Dto.name = "name12";
    childClass21Dto.anotherParentField = 21;
    childClass21Dto.intField = 210;
    parentClassDtos.add(childClass21Dto);

    childClass1Dto.relation = parentClassDtos;

    ParentClass parentClass = Mappers.getMapper(ParentClassMapper.class).convertDTOToModel(childClass1Dto);
  }

与mapstruct不同类型的列表的映射元素

1 个答案: