省市区三级联动（后端）

前提：springboot、mybatis-plus、swagger

数据库：

文章顶部

实体类：

City

package com.itfly.entity;


import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableId;
import java.time.LocalDateTime;
import java.io.Serializable;


import io.swagger.annotations.ApiModel;
import io.swagger.annotations.ApiModelProperty;
import lombok.Data;


/**
 * <p>
 * 基础表-省市区
 * </p>
 *
 * @author author
 * @since 2025-01-02
 */
@Data
@ApiModel(value="City对象", description="市")
public class City implements Serializable {

    private static final long serialVersionUID = 1L;

    @ApiModelProperty(value = "ID")
    @TableId(value = "city_id", type = IdType.AUTO)
    private Long cityId;

    @ApiModelProperty(value = "创建时间")
    private LocalDateTime createTime;

    @ApiModelProperty(value = "更新时间")
    private LocalDateTime updateTime;

    @ApiModelProperty(value = "名称")
    private String name;

    @ApiModelProperty(value = "区域编号")
    private String code;

    @ApiModelProperty(value = "层级 1,2,3")
    private Integer level;

    @ApiModelProperty(value = "父级ID")
    private Integer parentId;

    @ApiModelProperty(value = "拼音首字母缩写")
    private String acronym;

    @ApiModelProperty(value = "排序")
    private Integer sort;


}

DTO：省份---ProvinceDto

package com.itfly.dto.city;

import io.swagger.annotations.ApiModel;
import io.swagger.annotations.ApiModelProperty;
import lombok.Data;

import java.util.List;

@Data
@ApiModel(value="ProvinceDto", description="省")
public class ProvinceDto {
    @ApiModelProperty(value = "ID")
    private Long cityId;

    @ApiModelProperty(value = "名称")
    private String name;

    @ApiModelProperty(value = "区域编号")
    private String code;

    @ApiModelProperty(value = "层级 1,2,3")
    private Integer level;

    @ApiModelProperty(value = "父级ID")
    private Integer parentId;


    @ApiModelProperty(value = "2级市列表")
    private List<CityDto> cityList;
}

市：CityDto

package com.itfly.dto.city;


import io.swagger.annotations.ApiModel;
import io.swagger.annotations.ApiModelProperty;
import lombok.Data;

import java.util.List;

/**
 * <p>
 * 基础表-省市区
 * </p>
 *
 * @author author
 * @since 2025-01-02
 */
@Data
@ApiModel(value="CityDto", description="市")
public class CityDto {


    @ApiModelProperty(value = "ID")
    private Long cityId;

    @ApiModelProperty(value = "名称")
    private String name;

    @ApiModelProperty(value = "区域编号")
    private String code;

    @ApiModelProperty(value = "层级 1,2,3")
    private Integer level;

    @ApiModelProperty(value = "父级ID")
    private Integer parentId;

    @ApiModelProperty(value = "3级区县列表")
    private List<DistrictDto> districtList;


}

区县：DistrictDto

package com.itfly.dto.city;

import io.swagger.annotations.ApiModel;
import io.swagger.annotations.ApiModelProperty;
import lombok.Data;

@Data

@ApiModel(value="DistrictDto", description="区县")
public class DistrictDto {
    @ApiModelProperty(value = "ID")
    private Long cityId;

    @ApiModelProperty(value = "名称")
    private String name;

    @ApiModelProperty(value = "区域编号")
    private String code;

    @ApiModelProperty(value = "层级 1,2,3")
    private Integer level;

    @ApiModelProperty(value = "父级ID")
    private Integer parentId;


}

业务层逻辑：

控制器：

package com.itfly.controller;



import com.itfly.conf.result.R;
import com.itfly.service.ICityService;
import io.swagger.annotations.Api;
import io.swagger.annotations.ApiOperation;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

/**
 * <p>
 * 基础表-省市区 前端控制器
 * </p>
 *
 * @author author
 * @since 2025-01-02
 */
@RestController
@RequestMapping("/city")
@Api(tags = "省市区管理")
public class CityController {
    @Autowired
    private ICityService cityService;
    //查询省市列表
    @GetMapping("/getAll")
    @ApiOperation(value = "查询省市列表(三级联动)")
    public R getProvince() {
        return cityService.getProvince();
    }
}

service:

package com.itfly.service;


import com.itfly.conf.result.R;
import com.itfly.entity.City;
import com.baomidou.mybatisplus.extension.service.IService;

/**
 * <p>
 * 基础表-省市区 服务类
 * </p>
 *
 * @author author
 * @since 2025-01-02
 */
public interface ICityService extends IService<City> {

    R getProvince();
}

ServiceImpl

package com.itfly.service.impl;


import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.itfly.conf.result.R;
import com.itfly.dto.city.DistrictDto;
import com.itfly.dto.city.ProvinceDto;
import com.itfly.entity.City;
import com.itfly.dto.city.CityDto;
import com.itfly.mapper.CityMapper;
import com.itfly.service.ICityService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.itfly.vo.CityVo;
import org.springframework.stereotype.Service;
import org.springframework.util.ObjectUtils;

import java.util.List;

/**
 * <p>
 * 基础表-省市区 服务实现类
 * </p>
 *
 * @author author
 * @since 2025-01-02
 */
@Service
public class CityServiceImpl extends ServiceImpl<CityMapper, City> implements ICityService {
    @Override
    public R getProvince() {
        // 创建一个QueryWrapper用于查询省份（level为1）
        QueryWrapper<City> queryWrapperProvince = new QueryWrapper<>();
        queryWrapperProvince.eq("level", 1);
        // 查询所有省份
        List<City> listProvince = list(queryWrapperProvince);

        // 将查询到的省份列表转换为ProvinceDto列表
        List<ProvinceDto> provinceDtos = listProvince.stream().map(province -> {
            ProvinceDto provinceDto = new ProvinceDto();
            // 设置省份的基本信息
            provinceDto.setCityId(province.getCityId());
            provinceDto.setName(province.getName());
            provinceDto.setCode(province.getCode());
            provinceDto.setLevel(province.getLevel());
            provinceDto.setParentId(province.getParentId());

            // 创建一个QueryWrapper用于查询城市（level为2且parent_id为省份的cityId）
            QueryWrapper<City> queryWrapperCity = new QueryWrapper<>();
            queryWrapperCity.eq("level", 2).eq("parent_id", province.getCityId());
            // 查询所有城市
            List<City> listCity = list(queryWrapperCity);

            // 将查询到的城市列表转换为CityDto列表
            List<CityDto> cityDtos = listCity.stream().map(city -> {
                CityDto cityDto = new CityDto();
                // 设置城市的基本信息
                cityDto.setCode(city.getCode());
                cityDto.setName(city.getName());
                cityDto.setLevel(city.getLevel());
                cityDto.setParentId(city.getParentId());
                cityDto.setCityId(city.getCityId());

                // 创建一个QueryWrapper用于查询区县（level为3且parent_id为城市的cityId）
                QueryWrapper<City> queryWrapperArea = new QueryWrapper<>();
                queryWrapperArea.eq("level", 3).eq("parent_id", city.getCityId());
                // 查询所有区县
                List<City> listArea = list(queryWrapperArea);

                // 将查询到的区县列表转换为DistrictDto列表
                List<DistrictDto> areaDtos = listArea.stream().map(area -> {
                    DistrictDto areaDto = new DistrictDto();
                    // 设置区县的基本信息
                    areaDto.setCode(area.getCode());
                    areaDto.setName(area.getName());
                    areaDto.setLevel(area.getLevel());
                    areaDto.setParentId(area.getParentId());
                    areaDto.setCityId(area.getCityId());
                    return areaDto;
                }).toList();

                // 设置城市对应的区县列表
                cityDto.setDistrictList(areaDtos);
                return cityDto;
            }).toList();

            // 设置省份对应的城市列表
            provinceDto.setCityList(cityDtos);
            return provinceDto;
        }).toList();

        // 返回封装好的省份、城市和区县列表
        return R.Success(provinceDtos);
    }

}

打开swagger查看：