转载 树结构

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;   
    }   
}


public class Recursion {

StringBuffer returnStr=new StringBuffer(); 
    List nodeList =new ArrayList();   
//  构造方法里初始化模拟List,添加测试数据 
    Recursion() 
    { 
        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);     
    }   
     
    /**
     * 递归函数
     * @param list 要递归的节点对象集合
     * @param node 要进行递归的节点
     */ 
    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},");     
        }     
             
    }     
     
    /**
     * 判断是否有孩子
     * @param list
     * @param node
     * @return
     */ 
    public boolean hasChild(List list, Node node){  //判断是否有子节点   
        return getChildList(list,node).size()>0?true:false;   
    }   
     
    /**
     * 找去node的所有子节点
     * @param list 进行遍历的节点
     * @param node 要找孩子的节点
     * @return
     */ 
    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()));     
    }     
}