springboot实现省市区三级联查

在Spring Boot中实现省市区三级联查，通常需要建立数据库表格来存储省、市、区的数据，并提供相应的API接口。以下是一个简单的示例：

1. 创建数据库表格：

CREATE TABLE `region` (
  `id` bigint NOT NULL AUTO_INCREMENT,
  `name` varchar(255) NOT NULL,
  `parent_id` bigint DEFAULT NULL,
  PRIMARY KEY (`id`)
);

2. 实体类（Region.java）：

import javax.persistence.Entity;
import javax.persistence.Id;
 
@Entity
public class Region {
    @Id
    private Long id;
    private String name;
    private Long parentId;
 
    // 省略getter和setter
}

3. Repository接口（RegionRepository.java）：

import org.springframework.data.jpa.repository.JpaRepository;
 
public interface RegionRepository extends JpaRepository<Region, Long> {
    List<Region> findByParentId(Long parentId);
}

4. 服务类（RegionService.java）：

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
 
import java.util.List;
 
@Service
public class RegionService {
    @Autowired
    private RegionRepository regionRepository;
 
    public List<Region> getProvinceList() {
        return regionRepository.findByParentId(null);
    }
 
    public List<Region> getCityList(Long provinceId) {
        return regionRepository.findByParentId(provinceId);
    }
 
    public List<Region> getDistrictList(Long cityId) {
        return regionRepository.findByParentId(cityId);
    }
}

5. 控制器类（RegionController.java）：

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
 
import java.util.List;
 
@RestController
public class RegionController {
    @Autowired
    private RegionService regionService;
 
    @GetMapping("/region/province")
    public List<Region> getProvinceList() {
        return regionService.getProvinceList();
    }
 
    @GetMapping("/region/city")
    public List<Region> getCityList(@RequestParam Long provinceId) {
        return regionService.getCityList(provinceId);
    }
 
    @GetMapping("/region/district")
    public List<Region> getDistrictList(@RequestParam Long cityId) {
        retur