如何映射到泛型类型？

Question

页面信息

public class PageInfoDto<T> implements Serializable {

    private int currentPageNum;

    private int totalPageNum;

    private int perPageNum;

    private int totalItemNum;

    private List<T> list;

}

页

public class Page<T> implements Serializable {

    private int current;

    private int total;

    private int size;

    private int items;

    private List<T> list;

}

比如说，我有一个学校名单和一个学生名单。

我想将 Page 映射到 PageInfoDto 并将 Page 映射到 PageInfoDto？

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做法。有一个更好的方法吗？

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执行此操作，您可以在该方法上定义所有@Mapping注释并忽略泛型类型映射。您仍然可以使用上述方法，但您只需指定@InheritConfiguration

或者，您可以考虑使用 objectfactory@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，但请告诉我它是否有效

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> {

    }