Java 树父节点递归获取树子节点

package nodes4j;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

/**
* 获取子节点
*/
public class NodeUtil {

private List<Long> returnList = new ArrayList<Long>();

/**
* 根据父节点的ID获取所有子节点
* @param list 分类表
* @param typeId 传入的父节点ID
* @return String
*/
public String getChildNodes(List<Node> list, Long typeId) {
if(list == null && typeId == null) return "";
for (Iterator<Node> iterator = list.iterator(); iterator.hasNext();) {
Node node = (Node) iterator.next();
// 一、根据传入的某个父节点ID,遍历该父节点的所有子节点
if (node.getParentId()==0 && typeId==node.getId()) {
recursionFn(list, node);
}
// 二、遍历所有的父节点下的所有子节点
/*if (node.getParentId()==0) {
recursionFn(list, node);
}*/
}
return returnList.toString();
}

private void recursionFn(List<Node> list, Node node) {
List<Node> childList = getChildList(list, node);// 得到子节点列表
if (hasChild(list, node)) {// 判断是否有子节点
returnList.add(node.getId());
Iterator<Node> it = childList.iterator();
while (it.hasNext()) {
Node n = (Node) it.next();
recursionFn(list, n);
}
} else {
returnList.add(node.getId());
}
}

// 得到子节点列表
private List<Node> getChildList(List<Node> list, Node node) {
List<Node> nodeList = new ArrayList<Node>();
Iterator<Node> it = list.iterator();
while (it.hasNext()) {
Node n = (Node) it.next();
if (n.getParentId() == node.getId()) {
nodeList.add(n);
}
}
return nodeList;
}

// 判断是否有子节点
private boolean hasChild(List<Node> list, Node node) {
return getChildList(list, node).size() > 0 ? true : false;
}

// 本地模拟数据测试
public static void main(String[] args) {
long start = System.currentTimeMillis();
List<Node> nodeList = new ArrayList<Node>();
Node node1 = new Node(1l, "蔬菜", 0l);
Node node2 = new Node(2l, "水产", 0l);
Node node3 = new Node(3l, "畜牧", 0l);
Node node4 = new Node(4l, "瓜类", 1l);
Node node5 = new Node(5l, "叶类", 1l);
Node node6 = new Node(6l, "丝瓜", 4l);
Node node7 = new Node(7l, "黄瓜", 4l);
Node node8 = new Node(8l, "白菜", 1l);
Node node9 = new Node(9l, "虾", 2l);
Node node10 = new Node(10l, "鱼", 2l);
Node node11 = new Node(11l, "牛", 3l);

nodeList.add(node1);
nodeList.add(node2);
nodeList.add(node3);
nodeList.add(node4);
nodeList.add(node5);
nodeList.add(node6);
nodeList.add(node7);
nodeList.add(node8);
nodeList.add(node9);
nodeList.add(node10);
nodeList.add(node11);

NodeUtil mt = new NodeUtil();
System.out.println(mt.getChildNodes(nodeList, 1l));
long end = System.currentTimeMillis();
System.out.println("用时:" + (end - start) + "ms");
}

}

package nodes4j;
/**
* 无限级节点模型
*/
public class Node {
/**
* 节点id
*/
private Long id;

/**
* 节点名称
*/
private String nodeName;

/**
* 父节点id
*/
private Long parentId;

public Node() {
}

Node(Long id, Long parentId) {
this.id = id;
this.parentId = parentId;
}

Node(Long id, String nodeName, Long parentId) {
this.id = id;
this.nodeName = nodeName;
this.parentId = parentId;
}

public Long getId() {
return id;
}

public void setId(Long id) {
this.id = id;
}

public Long getParentId() {
return parentId;
}

public void setParentId(Long parentId) {
this.parentId = parentId;
}

public String getNodeName() {
return nodeName;
}

public void setNodeName(String nodeName) {
this.nodeName = nodeName;
}

}