java递归查询省市区树形结构

具体代码实现如下：

1@RequestMapping("getTree")
2    public Map<String, Object> getTree(int id) {
3        Map<String, Object> map = new HashMap<>();
4        try {
5            ChinaCitys province = dao.findProvince(id); //查询出一个省
6            if (province != null) {
7                List<ChinaCitys> citys = dao.findChildren(province.getId());//查询省下面的所有市
8                digui(citys); //调用递归算法查询市以下的区县
9                province.setChildren(citys);
10            }
11            map.put("data", province);
12        } catch (Exception e) {
13            e.printStackTrace();
14        }
15        return map;
16    }
17
18    public void digui(List<ChinaCitys> citys) {
19        List<ChinaCitys> retList = new ArrayList<>();
20        for (ChinaCitys c : citys) {
21            retList = dao.findChildren(c.getId());
22            if (retList.size() > 0) {
23                c.setChildren(retList);
24                digui(retList); //循环调用自己
25            }
26        }
27    }

sql语句：

1<select id="findProvince" parameterType="java.lang.Integer" resultMap="BaseResultMap">
2             select id,name from china_citys
3             WHERE id = #{id}
4    </select>
5
6    <select id="findChildren" parameterType="java.lang.Integer" resultMap="BaseResultMap">
7        select id,name  from china_citys
8        WHERE upid = #{id}
9    </select>