ExtJs树的递归算法(Java)，Json格式

首先先建立Node模型

public class Node {       private int id;       private int parentId;       Node(){}       Node(int id,int parentId){           this.id=id;           this.parentId = parentId;       }       public int getId() {           return id;       }       public void setId(int id) {           this.id = id;       }       public int getParentId() {           return parentId;       }       public void setParentId(int parentId) {           this.parentId = parentId;       }   }  

 

下面这个类先手工建立List，在实际应用中是从数据库读取List，然后再Main方法里调用递归方法，得到Json字符串

import java.util.ArrayList;   import java.util.Iterator;   import java.util.List;       public class Recursion {       List nodeList =new ArrayList();       Recursion(){//构造方法里初始化模拟List           Node node1 = new Node(1,0);             Node node2 = new Node(2,1);             Node node3 = new Node(3,1);             Node node4 = new Node(4,2);             Node node5 = new Node(5,2);             Node node6 = new Node(6,2);             Node node7 = new Node(7,6);             Node node8 = new Node(8,6);                          nodeList.add(node1);             nodeList.add(node2);             nodeList.add(node3);             nodeList.add(node4);             nodeList.add(node5);             nodeList.add(node6);             nodeList.add(node7);             nodeList.add(node8);         }       StringBuffer returnStr=new StringBuffer();         public void recursionFn(List list , Node node){             if(hasChild(list,node)){                 returnStr.append("{id:");               returnStr.append(node.getId());               returnStr.append(",parentId:");               returnStr.append(node.getParentId());               returnStr.append(",children:[");                 List childList = getChildList(list,node);                 Iterator it = childList.iterator();                 while(it.hasNext()){                     Node n = (Node)it.next();                     recursionFn(list,n);                 }                 returnStr.append("]},");             }else{                 returnStr.append("{id:");               returnStr.append(node.getId());               returnStr.append(",parentId:");               returnStr.append(node.getParentId());               returnStr.append(",leaf:true},");             }                      }         public boolean hasChild(List list, Node node){  //判断是否有子节点           return getChildList(list,node).size()>0?true:false;       }       public List getChildList(List list , Node node){  //得到子节点列表           List li = new ArrayList();             Iterator it = list.iterator();             while(it.hasNext()){                 Node n = (Node)it.next();                 if(n.getParentId()==node.getId()){                     li.add(n);                 }             }             return li;         }       public String modifyStr(String returnStr){//修饰一下才能满足Extjs的Json格式           return ("["+returnStr+"]").replaceAll(",]", "]");                  }       public static void main(String[] args) {             Recursion r = new Recursion();             r.recursionFn(r.nodeList, new Node(1,0));             System.out.println(r.modifyStr(r.returnStr.toString()));         }     }  

Main方法运行效果如下：
[{id:1,parentId:0,children:[{id:2,parentId:1,children:[{id:4,parentId:2,leaf:true},{id:5,parentId:2,leaf:true},{id:6,par
entId:2,children:[{id:7,parentId:6,leaf:true},{id:8,parentId:6,leaf:true}]}]},{id:3,parentId:1,leaf:true}]}]
在具体的应用中稍加修改即可

本文章来自：http://emlyn1180.iteye.com/blog/315334