Java recursively gets TreeJson

Union MyBatis, which is obtained by Map

The source code is as follows

Package com.zl.demo;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;/** * Java recursively obtains TreeJson * @ author ZhangLi * @ date at 11:10:45 on June 18, 2019 * @ WeiXin zl4828 * @ original provision of foam gold foam, for reference only * / public class TreeJson {public static void main (String [] args) {TreeJson treeJson = new TreeJson () TreeJson.treeMap.add (new HashMap () {{put ("ID", "0"); put ("NAME", "root node"); put ("PID", "null");}}); treeJson.treeMap.add (new HashMap () {{put ("ID", "1"); put ("NAME", "Node 1") Put ("PID", "0");}}); treeJson.treeMap.add (new HashMap () {{put ("ID", "2"); put ("NAME", "Node 2"); put ("PID", "0");}}) TreeJson.treeMap.add (new HashMap () {{put ("ID", "3"); put ("NAME", "Node 3"); put ("PID", "0");}}); treeJson.treeMap.add (new HashMap () {{put ("ID", "11"); put ("NAME", "Node 11") Put ("PID", "1");}}); treeJson.treeMap.add (new HashMap () {{put ("ID", "12"); put ("NAME", "node 12"); put ("PID", "1");}}) TreeJson.treeMap.add (new HashMap () {{put ("ID", "13"); put ("NAME", "Node 13"); put ("PID", "1");}}); System.out.println (treeJson.recursiveTree ("0"));} private List treeMap = new ArrayList () / / Global variable / * * Recursive algorithm parses into a tree structure * @ param pid * / public Map recursiveTree (String pid) {Map node = getNodeById (pid); List childrenList = new ArrayList (); if (null==node) {return node;} List childTreeNodes = getChildTreeById (pid) For (Map child: childTreeNodes) {Map n = recursiveTree (String.valueOf (child.get ("ID"); childrenList.add (n);} node.put ("children", childrenList); return node } / * query node objects according to pid * / public Map getNodeById (String pid) {for (Map node: treeMap) {if (null! = pid) {if (pid.equals (node.get ("ID") {return node;} return null } / * all nodes are obtained according to the parent node pid * / public List getChildTreeById (String pid) {List list = new ArrayList () If (null! = treeMap) {for (Map node: treeMap) {if (null! = pid) {if (pid.equals (node.get ("PID") {list.add (node);} return list }}

Application scenario

For example, the Echarts tree graph

Note that using JSON transformations

{name: 'root node', pid: null, id: 0, children: [{name: 'node 1 node, pid: 0, id: 1, children: [{name:' node 11 node, pid: 1, id: 11, children: []} {name: 'node 12, pid: 1, id: 12, children: []}, {name:' node 13, pid: 1, id: 13, children: []}}, {name: 'node 2' Pid: 0, id: 2, children: []}, {name: 'node 3percent, pid: 0, id: 3, children: []}}

Above, copy and run locally, any application.