表1：資料表，欄位主要有：id,name,file_location_id(bigint),theme_name_id(bigint), labels(String型別，實際是ids，有',')

表2：目錄表，欄位主要有：id,file_location(String)

表3：主題表，欄位主要有：id,theme_name(String)

表4：標籤表，欄位主要有：id,label(String)

VO層

@Data
public class BasicVO{
  
  private Long id;
  
  private String name;
  
  private String fileLocation;
  
  private String themeName;
  
  private String label;
}
 

serviceImpl層

@Service
public class BasicServiceImpl implements BasicService{
  @Autowired
  private BasicMapper basicMapper;
  
  @Autowired
  private LabelMapper labelMapper;
​
  @Autowired
  private FileMapper fileMapper;
​
  @Autowired
  private ThemeMapper themeMapper;
  
  /**
   * 分頁查詢
   */
  @Override
  public Page<Basic> selectList(Integer page, Integer limit) {
    Page pageData = new Page<>(page,limit);
    IPage<Basic> basicIPage = basicMapper.selectPage(pageData, null);
    List<Basic> records = basicIPage.getRecords();
        
    List<BasicVO> basicVOList = new ArrayList<>();
    for (Basic basic : records) {
      BasicVO basicVO = new BasicVO();
      BeanUtils.copyProperties(basic,basicVO);
      
      //查詢目錄的條件構造器，'id'為目錄表的id，basic.getFileLocationId()為資料表的關聯id
      QueryWrapper queryWrapper =new QueryWrapper();
      queryWrapper.eq("id",basic.getFileLocationId());
      basicVO.setFileLocation(fileMapper.selectOne(queryWrapper).getFileLocation());
      
            //查詢主題名稱的條件構造器，'id'為主題表的id，basic.getThemeNameId()為資料表的關聯id
      QueryWrapper queryWrapper1 =new QueryWrapper();
      queryWrapper1.eq("id",basic.getThemeNameId());
      basicVO.setThemeName(themeMapper.selectOne(queryWrapper1).getName());
            
      // 獲取標籤的ids
      String labels = basic.getLabels();
      String[] split = labels.split(",");
      // 將String型別的陣列 轉換成Long 型別的List
      Long[] longs =(Long[]) ConvertUtils.convert(split ,Long.class);
      List<Long> idsLong = Arrays.asList(longs);
      
      List<Label> labels = labelMapper.selectBatchIds(idsLong);
      String str ="";
      for (Label label : labels) {
        String sName = label.getName();
        str += ","+sName;
       }
      basicVO.setLabel(str.substring(1));
​
      basicVOList.add(basicVO);
     }
    pageData.setRecords(basicVOList);
    return pageData;
   }
}
​
​
 

省略其他層

根據不同需求和不同前端框架處理結果就可以了