查询城市列表

@Override
public String listCity(String parentId) throws Exception {
    List<City> all = cityMapper.selectProvinceInfo();
    Map<String, City> cityMap = new HashMap<>();
    List<City> result = new ArrayList<>();
    for (City city : all){
        cityMap.put(city.getCitycode(), city);
    }
    for (City city : all){
        if (city.getCityparentcode().equals("0")){
            result.add(city);
        }else {
            cityMap.get(city.getCityparentcode()).getChildren().add(city);
        }
    }


    return JSONObject.toJSONString(result);
}

public class City {
    private String citycode;

    private String cityname;

    private String cityparentcode;

    private Integer citylevel;
    private List<City> children = new ArrayList<>();

    public List<City> getChildren() {
        return children;
    }

    public void setChildren(List<City> children) {
        this.children = children;
    }

    public String getCitycode() {
        return citycode;
    }

    public void setCitycode(String citycode) {
        this.citycode = citycode == null ? null : citycode.trim();
    }

    public String getCityname() {
        return cityname;
    }

    public void setCityname(String cityname) {
        this.cityname = cityname == null ? null : cityname.trim();
    }

    public String getCityparentcode() {
        return cityparentcode;
    }

    public void setCityparentcode(String cityparentcode) {
        this.cityparentcode = cityparentcode == null ? null : cityparentcode.trim();
    }

    public Integer getCitylevel() {
        return citylevel;
    }

    public void setCitylevel(Integer citylevel) {
        this.citylevel = citylevel;
    }
}