java后台实现三级查询的功能

java后台实现这种数据类型：

[
    {
        "nextlevel1": [
            {
                "nextlevel2": [
                    {
                        "nextlevel3": [
                            {
                                "dept_name": "深圳总公司研发部门下级部门",
                                "dept_id": 114
                            }
                        ],
                        "dept_name": "研发部门",
                        "dept_id": 103
                    },
                    {
                        "dept_name": "运维部门",
                        "dept_id": 107
                    }
                ],
                "dept_name": "深圳总公司",
                "dept_id": 101
            },
            {
                "nextlevel2": [
                    {
                        "dept_name": "市场部门",
                        "dept_id": 108
                    },
                    {
                        "dept_name": "财务部门",
                        "dept_id": 109
                    }
                ],
                "dept_name": "长沙分公司",
                "dept_id": 102
            },
            {
                "nextlevel2": [
                    {
                        "dept_name": "财务部门",
                        "dept_id": 127
                    },
                    {
                        "dept_name": "财务部门11",
                        "dept_id": 131
                    }
                ],
                "dept_name": "日照分公司",
                "dept_id": 123
            },
            {
                "dept_name": "弗格森市分公司的感受到跟不上",
                "dept_id": 124
            },
            {
                "dept_name": "财务部门5",
                "dept_id": 128
            }
        ],
        "dept_name": "RuoYi科技",
        "dept_id": 100
    },
    {
        "nextlevel1": [
            {
                "nextlevel2": [
                    {
                        "nextlevel3": [
                            {
                                "nextlevel4": [
                                    {
                                        "nextlevel5": [
                                            {
                                                "dept_name": "6级",
                                                "dept_id": 142
                                            }
                                        ],
                                        "dept_name": "5级",
                                        "dept_id": 141
                                    }
                                ],
                                "dept_name": "4级",
                                "dept_id": 140
                            }
                        ],
                        "dept_name": "应急财务部门",
                        "dept_id": 112
                    },
                    {
                        "dept_name": "应急市场部门",
                        "dept_id": 113
                    }
                ],
                "dept_name": "应急分局",
                "dept_id": 111
            }
        ],
        "dept_name": "应急局",
        "dept_id": 110
    }
]

方法一：只实现三级查询

 

java代码如下：
   

startPage();
List<Map> levelone  = wxGovUserService.selectWxGovDepList();
List<Map> list1 = new ArrayList<>();
List<Map> levelthree = new ArrayList<>();
List<Map> leveltwo  = new ArrayList<>();
for (int i= 0;i<levelone.size();i++){

    levelone.get(i).put("levelone_deptname",levelone.get(i).remove("dept_name"));
    levelone.get(i).put("levelone_deptid",levelone.get(i).remove("dept_id"));
    String DepId =  levelone.get(i).get("levelone_deptid").toString();
    leveltwo  =  wxGovUserService.selectWxGovDepofficeList(DepId);
    for(int j = 0; j < leveltwo.size(); j++){
        leveltwo.get(j).put("leveltwo_deptname",leveltwo.get(j).remove("dept_name"));
        leveltwo.get(j).put("leveltwo_deptid",leveltwo.get(j).remove("dept_id"));

        String DepIdThree =  leveltwo.get(j).get("leveltwo_deptid").toString();
        levelthree  =  wxGovUserService.selectWxGovDepofficeList(DepIdThree);
        for(int m = 0; m < levelthree.size(); m++){
            levelthree.get(m).put("levelthreedept_deptid",levelthree.get(m).remove("dept_id"));
            levelthree.get(m).put("levelthreedept_name",levelthree.get(m).remove("dept_name"));
        }
        leveltwo.get(j).put("levelthree_list",levelthree);
    }
    levelone.get(i).put("leveltwo_list", leveltwo);
    list1.add(levelone.get(i));
}
return list1;

方法二：通过递归实现n级查询

    
　　　　 //递归调用函数
　　　　 private  List<Map> getdeplistcircle(String DepId,int m) {
        List<Map> leveldown = new ArrayList<>();
        int j = m;
        leveldown  =  wxGovUserService.selectWxGovDepofficeList(DepId);
        if(leveldown != null){
            for (int i = 0; i < leveldown.size(); i++) {
                String DepIdDown = leveldown.get(i).get("dept_id").toString();
                if(DepIdDown  != null){
                    int x = ++j;
                    List<Map> nextlevel = getdeplistcircle(DepIdDown,x);
                    if(nextlevel.size() == 0){
                        continue;
                    }else{
                        int n = 1 +j++;
                        String nextleveljoin = "nextlevel" + m;
                        leveldown.get(i).put(nextleveljoin,nextlevel);
                    }
                }else{
                    continue;
                }
            }
            return leveldown;
        }else{
            return null;
        }
    }

   //主函数
　　@PostMapping("/getgfgdgdlist")
    @ResponseBody
    @CrossOrigin
    public List getdeplist()
    {
        startPage();
        List<Map> levelone  = wxGovUserService.selectWxGovDepList();
        List<Map> list1 = new ArrayList<>();
        List<Map> levelthree = new ArrayList<>();
        List<Map> leveltwo  = new ArrayList<>();
        int j = 2;
        for (int i= 0;i<levelone.size();i++){

            String DepId =  levelone.get(i).get("dept_id").toString();
            if(DepId  != null){
                List<Map> leveldown = getdeplistcircle(DepId,j);

                if(leveldown.size() == 0){
                    continue;
                }else{
                    levelone.get(i).put("nextlevel1",leveldown);
                }
            }
        }
        return levelone;
    }

 三级查询mysql语句一次查出结果

 

select
    three.dept_id,three.dept_name,three.parent_id, three.ancestors
    ,jointable.dept_id,jointable.dept_name,jointable.parent_id,
    until_dept_id,until_dept_name
from sys_dept  three inner join
    (select two.dept_id,two.dept_name,two.parent_id, two.ancestors,one.dept_id as until_dept_id,one.dept_name as until_dept_name
     from sys_dept two inner join
     (select dept_id ,dept_name  from sys_dept where parent_id = 0)  one ON two.parent_id = one.dept_id)
jointable on  jointable.dept_id = three. parent_id

三级查询mysql语句一次查出结果