文章出自：http://www.cnblogs.com/dingyingsi/p/3699870.html
maven pom.xml
<dependency> <groupId>commons-collections</groupId> <artifactId>commons-collections</artifactId> <version>3.2.1</version> </dependency>
TreeBuilder.java
package com.yusj;
import java.util.ArrayList;
import java.util.List;
import org.apache.commons.collections.CollectionUtils;
public class TreeBuilder {
@SuppressWarnings("unchecked")
private List<Node> buildListToTree(List<Node> dirs) {
List<Node> roots = findRoots(dirs);
List<Node> notRoots = (List<Node>) CollectionUtils
.subtract(dirs, roots);
for (Node root : roots) {
root.setChildren(findChildren(root, notRoots));
}
return roots;
}
public List<Node> findRoots(List<Node> allNodes) {
List<Node> results = new ArrayList<Node>();
for (Node node : allNodes) {
boolean isRoot = true;
for (Node comparedOne : allNodes) {
if (node.getParentId() == comparedOne.getId()) {
isRoot = false;
break;
}
}
if (isRoot) {
node.setLevel(0);
results.add(node);
node.setRootId(node.getId());
}
}
return results;
}
@SuppressWarnings("unchecked")
private List<Node> findChildren(Node root, List<Node> allNodes) {
List<Node> children = new ArrayList<Node>();
for (Node comparedOne : allNodes) {
if (comparedOne.getParentId() == root.getId()) {
comparedOne.setParent(root);
comparedOne.setLevel(root.getLevel() + 1);
children.add(comparedOne);
}
}
List<Node> notChildren = (List<Node>) CollectionUtils.subtract(allNodes, children);
for (Node child : children) {
List<Node> tmpChildren = findChildren(child, notChildren);
if (tmpChildren == null || tmpChildren.size() < 1) {
child.setLeaf(true);
} else {
child.setLeaf(false);
}
child.setChildren(tmpChildren);
}
return children;
}
private List<Node> getLeafChildren(List<Node> resultList, List<Node> children){
for(Node node : children){
if(node.isLeaf()){
resultList.add(node);
}else{
getLeafChildren(resultList, node.getChildren());
}
}
return resultList;
}
public static void main(String[] args) {
TreeBuilder tb = new TreeBuilder();
List<Node> allNodes = new ArrayList<Node>();
allNodes.add(new Node(1, 0, "节点1"));
allNodes.add(new Node(2, 0, "节点2"));
allNodes.add(new Node(3, 0, "节点3"));
allNodes.add(new Node(4, 1, "节点4"));
allNodes.add(new Node(5, 1, "节点5"));
allNodes.add(new Node(6, 1, "节点6"));
allNodes.add(new Node(7, 4, "节点7"));
allNodes.add(new Node(8, 4, "节点8"));
allNodes.add(new Node(9, 5, "节点9"));
allNodes.add(new Node(10, 5, "节点10"));
allNodes.add(new Node(11, 7, "节点11"));
allNodes.add(new Node(12, 7, "节点12"));
// 显示所有节点
List<Node> roots = tb.buildListToTree(allNodes);
for (Node n : roots) {
System.out.println(n);
}
System.out.println("------------------");
// 查找所有子节点
List<Node> children = tb.findChildren(new Node(1, 0, "节点1"), allNodes);
for (Node n : children) {
System.out.println(n);
}
// 查找所有叶子节点
System.out.println("------------------");
List<Node> resultList = tb.getLeafChildren(new ArrayList<Node>(), children);
for (Node n : resultList) {
System.out.println(n);
}
}
}
Node.java
package com.yusj;
import java.util.List;
public class Node implements java.io.Serializable {
private static final long serialVersionUID = -2721191232926604726L;
private int id;
private int parentId;
private Node parent;
private List<Node> children;
private String name;
private int level;
private int sort;
private int rootId;
private String type;
private boolean isLeaf;
private String description;
public Node() {
super();
}
public Node(int id, int parentId, String name) {
super();
this.id = id;
this.parentId = parentId;
this.name = name;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public Node getParent() {
return parent;
}
public void setParent(Node parent) {
this.parent = parent;
}
public int getParentId() {
return parentId;
}
public void setParentId(int parentId) {
this.parentId = parentId;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getLevel() {
return level;
}
public void setLevel(int level) {
this.level = level;
}
public String getType() {
return type;
}
public List<Node> getChildren() {
return children;
}
public void setChildren(List<Node> children) {
this.children = children;
}
public void setType(String type) {
this.type = type;
}
public boolean isLeaf() {
return isLeaf;
}
public void setLeaf(boolean isLeaf) {
this.isLeaf = isLeaf;
}
public int getSort() {
return sort;
}
public void setSort(int sort) {
this.sort = sort;
}
public int getRootId() {
return rootId;
}
public void setRootId(int rootId) {
this.rootId = rootId;
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + id;
result = prime * result + parentId;
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
Node other = (Node) obj;
if (id != other.id)
return false;
if (parentId != other.parentId)
return false;
return true;
}
@Override
public String toString() {
return "Node {id=" + id + ", parentId=" + parentId + ", children="
+ children + ", name=" + name + ", level =" + level + ", isLeaf =" + isLeaf + "}";
}
}
shell
---------所有节点---------
Node {id=1, parentId=0, children=[Node {id=4, parentId=1, children=[Node {id=7, parentId=4, children=[Node {id=11, parentId=7, children=[], name=节点11, level =3, isLeaf =true}, Node {id=12, parentId=7, children=[], name=节点12, level =3, isLeaf =true}], name=节点7, level =2, isLeaf =false}, Node {id=8, parentId=4, children=[], name=节点8, level =2, isLeaf =true}], name=节点4, level =1, isLeaf =false}, Node {id=5, parentId=1, children=[Node {id=9, parentId=5, children=[], name=节点9, level =2, isLeaf =true}, Node {id=10, parentId=5, children=[], name=节点10, level =2, isLeaf =true}], name=节点5, level =1, isLeaf =false}, Node {id=6, parentId=1, children=[], name=节点6, level =1, isLeaf =true}], name=节点1, level =0, isLeaf =false}
Node {id=2, parentId=0, children=[], name=节点2, level =0, isLeaf =false}
Node {id=3, parentId=0, children=[], name=节点3, level =0, isLeaf =false}
---------<节点1>子节点---------
Node {id=4, parentId=1, children=[Node {id=7, parentId=4, children=[Node {id=11, parentId=7, children=[], name=节点11, level =3, isLeaf =true}, Node {id=12, parentId=7, children=[], name=节点12, level =3, isLeaf =true}], name=节点7, level =2, isLeaf =false}, Node {id=8, parentId=4, children=[], name=节点8, level =2, isLeaf =true}], name=节点4, level =1, isLeaf =false}
Node {id=5, parentId=1, children=[Node {id=9, parentId=5, children=[], name=节点9, level =2, isLeaf =true}, Node {id=10, parentId=5, children=[], name=节点10, level =2, isLeaf =true}], name=节点5, level =1, isLeaf =false}
Node {id=6, parentId=1, children=[], name=节点6, level =1, isLeaf =true}
--------<节点1>叶子节点----------
Node {id=11, parentId=7, children=[], name=节点11, level =3, isLeaf =true}
Node {id=12, parentId=7, children=[], name=节点12, level =3, isLeaf =true}
Node {id=8, parentId=4, children=[], name=节点8, level =2, isLeaf =true}
Node {id=9, parentId=5, children=[], name=节点9, level =2, isLeaf =true}
Node {id=10, parentId=5, children=[], name=节点10, level =2, isLeaf =true}
Node {id=6, parentId=1, children=[], name=节点6, level =1, isLeaf =true}