java使用递归将查询的数据转JSON树状结构数据
java使用递归将查询的数据转JSON树状结构数据
1.第一种情况，从数据库中查出数据如下：
使用以下代码进行转换，先提取pId为0的父节点，再把子节点递归提取出来
`public static List<Map> toTreeByMap(List<Map> list) {
List<Map> treeList = new ArrayList<>();
for (Map tree : list) {
if ("0".equals(tree.get("pId"))) {
treeList.add(tree);
}
}
for (Map tree : list) {
toTreeChildren(treeList, tree);
}
return treeList;
}
private static void toTreeChildren(List<Map> treeList, Map tree) {
for (Map node : treeList) {
if (tree.get("pId").equals(node.get("id"))) {
if (node.get("children") == null || "".equals(node.get("children"))) {
node.put("children", new ArrayList<Map>());
}
((ArrayList<Map>) node.get("children")).add(tree);
}
if (node.get("children") != null) {
toTreeChildren((ArrayList<Map>) node.get("children"), tree);
}
}
}`
转换完的数据如下:
{
"code": 1,
"message": "成功",
"result": {
"id": "0",
"pId": "-1",
"funcode": "sysmd",
"funname": "系统功能菜单",
"checked": 0,
"children": [
{
"funcode": "sysmd1",
"checked": 1,
"pId": "0",
"id": "a0980baf639679b4016396928fbb0001",
"funname": "首页"
},
{
"funcode": "sysmd2",
"checked": 1,
"pId": "0",
"id": "a0980baf639679b4016396928fbb0002",
"funname": "首页"
},
{
"funcode": "sysmd3",
"checked": 1,
"pId": "0",
"id": "a0980baf639679b4016396928fbb0003",
"funname": "监控告警",
"children": [
{
"funcode": "sysmd31",
"checked": 1,
"pId": "a0980baf639679b4016396928fbb0003",
"id": "a0980baf639679b4016396928fbb0008",
"funname": "设备告警"
},
{
"funcode": "sysmd32",
"checked": 1,
"pId": "a0980baf639679b4016396928fbb0003",
"id": "a0980baf639679b4016396928fbb0009",
"funname": "污染告警"
}
]
}
]
}
}
2.第二种情况，前端传过来的JSON数据转成List集合：
[
{
"id": "0",
"pId": "-1",
"funcode": "sysmd",
"funname": "系统功能菜单",
"checked": true,
"children": [
{
"funcode": "sysmd1",
"checked": true,
"pId": "0",
"id": "a0980baf639679b4016396928fbb0001",
"funname": "首页"
},
{
"funcode": "sysmd2",
"checked": true,
"pId": "0",
"id": "a0980baf639679b4016396928fbb0002",
"funname": "首页"
},
{
"funcode": "sysmd3",
"checked": true,
"pId": "0",
"id": "a0980baf639679b4016396928fbb0003",
"funname": "监控告警",
"children": [
{
"funcode": "sysmd31",
"checked": true,
"pId": "a0980baf639679b4016396928fbb0003",
"id": "a0980baf639679b4016396928fbb0008",
"funname": "设备告警"
},
{
"funcode": "sysmd32",
"checked": true,
"pId": "a0980baf639679b4016396928fbb0003",
"id": "a0980baf639679b4016396928fbb0009",
"funname": "污染告警"
}
]
}
]
}
]
后端使用String接收，然后序列化为List类型:
public Object setUserFunctionPermission(@RequestParam("list") String permfunctionmaplistjson){
ObjectMapper mapper = new ObjectMapper(); // 使用ObjectMapper反序列化json串为对象
List<Map> permfunctionmaplist = new ArrayList<>();
permfunctionmaplist = mapper.readValue(permfunctionmaplistjson, permfunctionmaplist.getClass());
//用于保存转换后的集合
List<Map> treeNode = new ArrayList<>();
//使用对象工具类中的方法进行递归转换
getTreeChildren(permfunctionmaplist, treeNode);
return treeNode;
}
//提取所有子节点
public static void getTreeChildren(List<Map> treeList, List<Map> lm) {
for (Map tree : treeList) {
if (tree.get("children") != null && !"".equals(tree.get("children"))) {
getTreeChildren((ArrayList<Map>) tree.get("children"), lm);
} else {
lm.add(tree);
}
}
}
提取出来的后treeNode数据为:
[{funcode=sysmd1,checked=1,pId=0,id=a0980baf639679b4016396928fbb0001,
funname=首页},
{funcode=sysmd2,checked=1,pId=0,id=a0980baf639679b4016396928fbb0002,
funname=首页},
{funcode=sysmd31,checked=1,pId=a0980baf639679b4016396928fbb0003,id=a0980baf639679b4016396928fbb0008, funname=设备告警},
{funcode=sysmd32,checked=1,pId=a0980baf639679b4016396928fbb0003,id=a0980baf639679b4016396928fbb0009, funname=污染告警}]