MapStruct 用于DTO等代码解耦

知识点

MapStruct 是一款基于注解的类字段映射工具，能够自动生成类字段映射的代码。可以自动或手动实现复杂的字段映射，深嵌套也能自动适配。

需求

业务对外提供Dubbo接口的时候，通常通过DTO与外部进行数据交换。要实现类的深拷贝非常麻烦，基于序列化的耗时，自己写的太麻烦。

处理方法

1. PO 和 DTO 代码

@Data
public class AnProjectInfoPo {
    private Integer id;
    private String projectName;
    private Integer type;
    private String desc;
    private String columns;
    private Integer createType;
    private Integer state;
    private Date createTime;
    private Date updateTime;
    private Integer createUser;
    private Integer updateUser;
    private Boolean isDeleted;
}

@Data
public class AnProjectInfoDTO {
    private Integer id;
    private String projectName;
    private Integer type;
    private String desc;
    private String columns;
    private Integer createType;
    private Integer state;
    private Date createTime;
    private Date updateTime;
    private Integer createUser;
    private Integer updateUser;
    private Boolean isDeleted;
}

2. 定义Mapper（不是Mybatis的那个）

public interface CommonMS<P,D> {
  D toDTO(P p);
  P toPo(D d);
  List<D> toDTO(List<P> pList);
  PageInfo<D> toPage(PageInfo<P> pageInfo);
}

@Mapper(componentModel = "spring")
public interface AnProjectInfoMS extends CommonMS<AnProjectInfoPo,AnProjectInfoDTO> {
  AnProjectInfoMS INSTANCE = Mappers.getMapper(AnProjectInfoMS.class);
}

3. 自动生成在target目录下的代码

@Generated(
    value = "org.mapstruct.ap.MappingProcessor",
    date = "2019-03-18T21:44:52+0800",
    comments = "version: 1.2.0.Final, compiler: javac, environment: Java 1.8.0_181 (Oracle Corporation)"
)
@Component
public class AnProjectInfoMSImpl implements AnProjectInfoMS {

    @Override
    public AnProjectInfoDTO toDTO(AnProjectInfoPo p) {
        if ( p == null ) {
            return null;
        }

        AnProjectInfoDTO anProjectInfoDTO = new AnProjectInfoDTO();

        anProjectInfoDTO.setId( p.getId() );
        anProjectInfoDTO.setProjectName( p.getProjectName() );
        anProjectInfoDTO.setType( p.getType() );
        anProjectInfoDTO.setDesc( p.getDesc() );
        anProjectInfoDTO.setColumns( p.getColumns() );
        anProjectInfoDTO.setCreateType( p.getCreateType() );
        anProjectInfoDTO.setState( p.getState() );
        anProjectInfoDTO.setCreateTime( p.getCreateTime() );
        anProjectInfoDTO.setUpdateTime( p.getUpdateTime() );
        anProjectInfoDTO.setCreateUser( p.getCreateUser() );
        anProjectInfoDTO.setUpdateUser( p.getUpdateUser() );
        anProjectInfoDTO.setIsDeleted( p.getIsDeleted() );

        return anProjectInfoDTO;
    }

    @Override
    public AnProjectInfoPo toPo(AnProjectInfoDTO d) {
        if ( d == null ) {
            return null;
        }

        AnProjectInfoPo anProjectInfoPo = new AnProjectInfoPo();

        anProjectInfoPo.setId( d.getId() );
        anProjectInfoPo.setProjectName( d.getProjectName() );
        anProjectInfoPo.setType( d.getType() );
        anProjectInfoPo.setDesc( d.getDesc() );
        anProjectInfoPo.setColumns( d.getColumns() );
        anProjectInfoPo.setCreateType( d.getCreateType() );
        anProjectInfoPo.setState( d.getState() );
        anProjectInfoPo.setCreateTime( d.getCreateTime() );
        anProjectInfoPo.setUpdateTime( d.getUpdateTime() );
        anProjectInfoPo.setCreateUser( d.getCreateUser() );
        anProjectInfoPo.setUpdateUser( d.getUpdateUser() );
        anProjectInfoPo.setIsDeleted( d.getIsDeleted() );

        return anProjectInfoPo;
    }

    @Override
    public List<AnProjectInfoDTO> toDTO(List<AnProjectInfoPo> pList) {
        if ( pList == null ) {
            return null;
        }

        List<AnProjectInfoDTO> list = new ArrayList<AnProjectInfoDTO>( pList.size() );
        for ( AnProjectInfoPo anProjectInfoPo : pList ) {
            list.add( toDTO( anProjectInfoPo ) );
        }

        return list;
    }

    @Override
    public PageInfo<AnProjectInfoDTO> toPage(PageInfo<AnProjectInfoPo> pageInfo) {
        if ( pageInfo == null ) {
            return null;
        }

        PageInfo<AnProjectInfoDTO> pageInfo1 = new PageInfo<AnProjectInfoDTO>();

        pageInfo1.setPageNum( pageInfo.getPageNum() );
        pageInfo1.setPageSize( pageInfo.getPageSize() );
        pageInfo1.setSize( pageInfo.getSize() );
        pageInfo1.setStartRow( pageInfo.getStartRow() );
        pageInfo1.setEndRow( pageInfo.getEndRow() );
        pageInfo1.setTotal( pageInfo.getTotal() );
        pageInfo1.setPages( pageInfo.getPages() );
        pageInfo1.setList( toDTO( pageInfo.getList() ) );
        pageInfo1.setFirstPage( pageInfo.getFirstPage() );
        pageInfo1.setPrePage( pageInfo.getPrePage() );
        pageInfo1.setNextPage( pageInfo.getNextPage() );
        pageInfo1.setLastPage( pageInfo.getLastPage() );
        pageInfo1.setIsFirstPage( pageInfo.isIsFirstPage() );
        pageInfo1.setIsLastPage( pageInfo.isIsLastPage() );
        pageInfo1.setHasPreviousPage( pageInfo.isHasPreviousPage() );
        pageInfo1.setHasNextPage( pageInfo.isHasNextPage() );
        pageInfo1.setNavigatePages( pageInfo.getNavigatePages() );
        int[] navigatepageNums = pageInfo.getNavigatepageNums();
        if ( navigatepageNums != null ) {
            pageInfo1.setNavigatepageNums( Arrays.copyOf( navigatepageNums, navigatepageNums.length ) );
        }
        pageInfo1.setNavigateFirstPage( pageInfo.getNavigateFirstPage() );
        pageInfo1.setNavigateLastPage( pageInfo.getNavigateLastPage() );

        return pageInfo1;
    }
}

4. Dubbo代码中使用，Dao层处理都用的PO，对外全提供DTO

import com.alibaba.dubbo.config.annotation.Service;
@Slf4j
@Service //com.alibaba.dubbo.config.annotation.Service;
@Component
public class ProjectInfoServiceImpl implements ProjectInfoService {

    @Autowired
    private AnProjectInfoDao anProjectInfoDao;
    
    @Override
    public List<AnProjectInfoDTO> selectById(int projectId) {
        return AnProjectInfoMS.INSTANCE.toDTO(anProjectInfoDao.selectById(projectId));
    }

    @Override
    public AnProjectInfoDTO selectOne(int projectId) {
        return AnProjectInfoMS.INSTANCE.toDTO(anProjectInfoDao.selectOneById(projectId));
    }
}