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 recursi
4000
onFn(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