如何映射到泛型类型？

Question

PageInfoDto<T>

：

public class PageInfoDto<T> {
    private int currentPageNum;
    private int totalPageNum;
    private int perPageNum;
    private int totalItemNum;
    private List<T> list;
}

Page<T>

：

public class Page<T> {
    private int current;
    private int total;
    private int size;
    private int items;
    private List<T> list;
}

我有学校名单和学生名单。

我想将

Page<School>

映射到

PageInfoDto<SchoolDto>

并将

Page<Student>

映射到

PageInfoDto<StudentDto>

。

这就是我的映射器的样子：

@Mapper(config = CentralConfig.class, uses = {StudentMapper.class, SchoolMapper.class}, componentModel = "spring")
public interface PageInfoMapper {
    @Mappings({
        @Mapping(target = "list", source = "pageInfo.records"),
        @Mapping(target = "currentPageNum", source = "pageInfo.current"),
        @Mapping(target = "totalPageNum", source = "pageInfo.pages"),
        @Mapping(target = "perPageNum", source = "pageInfo.size"),
        @Mapping(target = "totalItemNum", source = "pageInfo.total"),
    })
    PageInfoDto<SchoolDto> toPageInfoDto1(Page<School> pageInfo);

    @Mappings({
        @Mapping(target = "list", source = "pageInfo.records"),
        @Mapping(target = "currentPageNum", source = "pageInfo.current"),
        @Mapping(target = "totalPageNum", source = "pageInfo.pages"),
        @Mapping(target = "perPageNum", source = "pageInfo.size"),
        @Mapping(target = "totalItemNum", source = "pageInfo.total"),
    })
    PageInfoDto<StudentDto> toPageInfoDto2(Page<Student> pageInfo);
}

这显然不是一个聪明的方法，必须重复相同的代码。有更好的方法吗？

Answer 1

Mapstruct 是一个代码生成器。因此它需要知道要构造哪些类型才能生成方法实现。话虽如此，您可以通过使用基本映射方法来更智能地完成此操作，在该方法上定义所有

@Mapping

注释并忽略通用类型映射。您仍然可以使用上面的方法，但只需指定

@InheritConfiguration

或者，您可以考虑使用对象工厂，使用

@TargetType

来构造正确的泛型类型。我不确定这是否适用于通用映射方法签名。我无法检查它，但请告诉我这是否有效

例如

    public interface BasePageMapper<S, DTO> {

        @Mapping(target = "list", source = "records"),
        @Mapping(target = "currentPageNum", source = "current"),
        @Mapping(target = "totalPageNum", source = "pages"),
        @Mapping(target = "perPageNum", source = "size"),
        @Mapping(target = "totalItemNum", source = "total"),
        PageInfoDto<DTO> toPageInfoDto(Page<S> pageInfo);

        DTO toDto(S source);
    }

@Mapper( config = CentralConfig.class, uses = StudentMapper.class, componentModel = "spring")
    public interface StudentMapper extends BasePageMapper<Student, StudentDto> {

    }

@Mapper( config = CentralConfig.class, uses = SchoolMapper.class, componentModel = "spring")
    public interface SchoolMapper extends BasePageMapper<School, SchoolDto> {

    }