MapStruct：多个相同的平面源到多个相同的目标

Question

我想映射这个 DTO :

public class BikeDTO {
    private String wheel_1_color;
    private String wheel_1_shape;

    private String wheel_2_color;
    private String wheel_2_shape;
}

致该实体：

public class BikeEntity {
    private WheelEntity wheel1;
    private WheelEntity wheel2;
}

public class WheelEntity {
    private String color;
    private String shape;
}

所以，我想知道是否可以只使用一个像这样的 WheelMapper :

@Mapper
public interface BikeMapper {

    BikeMapper INSTANCE = Mappers.getMapper(BikeMapper.class);

    @Mapping(target="wheel1", source=".", qualifiedByName ="dtoToWheel")
    @Mapping(target="wheel2", source=".", qualifiedByName ="dtoToWheel")
    BikeEntity dtoToEntity(BikeDTO dto);

    @Named("dtoToWheel")
    default WheelEntity dtoToWheel(BikeDTO dto) {
        return WheelMapper.INSTANCE.dtoToWheel(dto);
    }
}

@Mapper
public interface WheelMapper {

    WheelMapper INSTANCE = Mappers.getMapper(WheelMapper.class);

    @Mapping(target="color", source="wheel_" + wheelNumber + "_color")
    @Mapping(target="shape", source="wheel_" + wheelNumber + "_shape")
    WheelEntity dtoToWheel(BikeDTO dto);
}

我被

wheelNumber

困住了，不知道如何设置。

我编写了这段代码来表达我的需求，但我会采取任何对我有帮助的解决方案。

我可能想错了，我需要你的帮助？

PS：我显然无法更改我的 DTO 或实体的结构。

Answer 1

我认为在您的映射结构映射器中实现自定义映射函数会更容易。如果您不想使用 mapstruct 来实现这个简单的映射函数，您也可以将其导出到普通类或静态函数。因为您并没有真正使用任何映射结构功能，但它更容易且更具可读性:)

@Mapper
public interface BikeMapper {

    default BikeEntity dtoToEntity(BikeDTO dto) {
        return new BikeEntity(
            new WheelEntity(dto.getWheel_1_Color(), dto.getWheel_1_Shape()),
            new WheelEntity(dto.getWheel_2_Color(), dto.getWheel_2_Shape())
        );
    }

}

// easiest way would be to use lombok or define an all args contructor for each of those two entities

@AllArgsContructor 
public class BikeEntity {
    private WheelEntity wheel1;
    private WheelEntity wheel2;
}

@AllArgsContructor
public class WheelEntity {
    private String color;
    private String shape;
}

---

如果您想使用mapstructs codegen，您可以在@Mapping中使用表达式，如下所示。多一点代码，不需要通过 mapstruct 生成它。在这两种解决方案中，如果自行车现在有 3 个轮子，则您必须调整映射器。所以你自己决定吧:D

@Mapper
public interface BikeMapper {

    BikeMapper INSTANCE = Mappers.getMapper(BikeMapper.class);

    @Mapping(target = "wheel1", expression = "java(WheelMapper.INSTANCE.dtoToWheel1(dto))")
    @Mapping(target = "wheel2", expression = "java(WheelMapper.INSTANCE.dtoToWheel2(dto))")
    BikeEntity dtoToEntity(BikeDTO dto);
}

@Mapper
public interface WheelMapper {

    WheelMapper INSTANCE = Mappers.getMapper(WheelMapper.class);

    @Mapping(target = "color", source = "wheel_1_color")
    @Mapping(target = "shape", source = "wheel_1_shape")
    WheelEntity dtoToWheel1(BikeDTO dto);

    @Mapping(target = "color", source = "wheel_2_color")
    @Mapping(target = "shape", source = "wheel_2_shape")
    WheelEntity dtoToWheel2(BikeDTO dto);
}