如下，我们要返回下面的数据格式

 

{      "value": "3",      "label": "安徽省",      "children": [        {          "value": "安庆市",          "label": "36",          "children1s": [            {              "label": "398",              "value": "迎江区"            },            {              "label": "399",              "value": "大观区"            },            {              "label": "400",              "value": "宜秀区"            },            {              "label": "401",              "value": "桐城市"            },            {              "label": "402",              "value": "怀宁县"            },            {              "label": "403",              "value": "枞阳县"            },            {

那么可以通过构造辅助类来完成

 

这里因为这里是三级，所以我就构造了三个辅助类

 

@Getter@Setterpublic class Data {    private String value;    private String label;    private List
    
      children;}
    

@Setter@Getterpublic class Children {    private String value;    private String label;    private List
    
      children1s;}
    

@Getter@Setterpublic class Children1 {    private String label;    private String value;}

我的mapper

 

 

//查询所有的省    @Select("select * from zone where pid = 1")    List
    
      selectProvince();    //查询该省所有的市    @Select("select * from zone where  pid =#{provinceId}")    List
     
       selectCityByProvinceId(String provinceId);    //查询该市对应的县    @Select("select * from zone where  pid =#{cityId}")    List
      
        selectCountyByCityId(String cityId);
      
     
    

接下来是我的serviceimpl

 

 

@Override    public Result selectAll() {        List dataList = null;        try {            dataList = new ArrayList();            List
      
        provinces = zoneInfoMapper.selectProvince();            for (ZoneInfo province : provinces) {                Data data = new Data();                data.setValue(String.valueOf(province.getId()));                data.setLabel(province.getDistrict());                List
       
         cities = zoneInfoMapper.selectCityByProvinceId(String.valueOf(province.getId()));                List
        
          childrenList = new ArrayList
         
          (); for (ZoneInfo city : cities) { Children children = new Children(); children.setLabel(String.valueOf(city.getId())); children.setValue(city.getDistrict()); childrenList.add(children); List
          
            counties = zoneInfoMapper.selectCountyByCityId(String.valueOf(city.getId())); List
           
             children1s = new ArrayList
            
             (); for (ZoneInfo county : counties) { Children1 children1 = new Children1(); children1.setLabel(String.valueOf(county.getId())); children1.setValue(county.getDistrict()); children1s.add(children1); } children.setChildren1s(children1s); } data.setChildren(childrenList); dataList.add(data); } } catch (Exception e) { Logger.logMsg(4, e.getMessage()); return Result.build(500, ErrorCode.UNKNOWN_ERROR.getStatusMsg()); } return Result.ok(dataList); }
            
           
          
         
        
       
      

这里需要注意的是

 

Data data = new Data();需要在for循环里面创建，因为对于不同的province都是一个data,然后每一个data最终添加到datalist里面。如果是在for循环外面实例化，就会被覆盖掉，导致datalist里面的数据只有最后一个

同样的下面的children以及children1也一样