首先看看两种树形菜单结构的代码示例。
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SingleTreeNode：
package com.zzj.tree;
public class SingleTreeNode {
private int id;
private int pId;
private String name;
public SingleTreeNode() {
}
public SingleTreeNode(int id, int pId, String name) {
this.id = id;
this.pId = pId;
this.name = name;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public int getpId() {
return pId;
}
public void setpId(int pId) {
this.pId = pId;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@Override
public String toString() {
return "SingleTreeNode [id=" + id + ", pId=" + pId + ", name=" + name + "]";
}
}这种结构很适合存储到关系型数据库中。
MultiTreeNode：
package com.zzj.tree;
import java.util.List;
public class MultiTreeNode {
private int id;
private String name;
private List children;
public MultiTreeNode() {
}
public MultiTreeNode(int id, String name) {
this.id = id;
this.name = name;
}
public MultiTreeNode(int id, String name, List children) {
this.id = id;
this.name = name;
this.children = children;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public List getChildren() {
return children;
}
public void setChildren(List children) {
this.children = children;
}
@Override
public String toString() {
return "MultiTreeNode [id=" + id + ", name=" + name + ", children=" + children + "]";
}
} 两种转换器
ToMultiTreeTransformer：
package com.zzj.tree;
import java.util.ArrayList;
import java.util.List;
public class ToMultiTreeTransformer {
private List singleTreeNodes;
private List multiTreeNodes = new ArrayList<>();
public ToMultiTreeTransformer(List singleTreeNodes) {
this.singleTreeNodes = singleTreeNodes;
}
public List transform(){
// 先找出所有的根节点
for (int i = 0; i < singleTreeNodes.size(); i++) {
SingleTreeNode singleTreeNode = singleTreeNodes.get(i);
Boolean isRoot = true;
for (int j = 0; j < singleTreeNodes.size(); j++) {
SingleTreeNode temp = singleTreeNodes.get(j);
if (singleTreeNode.getpId() == temp.getId()) {
isRoot = false;
break;
}
}
if (isRoot) {
MultiTreeNode multiTreeNode = new MultiTreeNode(singleTreeNode.getId(),
singleTreeNode.getName());
multiTreeNodes.add(multiTreeNode);
}
}
// 设置子节点
for (int i = 0; i < multiTreeNodes.size(); i++) {
MultiTreeNode multiTreeNode = multiTreeNodes.get(i);
setChildren(multiTreeNode);
}
return multiTreeNodes;
}
/**
* 设置子节点
* @param multiTreeNode
*/
private void setChildren(MultiTreeNode multiTreeNode){
for (int j = 0; j < singleTreeNodes.size(); j++) {
SingleTreeNode temp = singleTreeNodes.get(j);
if (temp.getpId() == multiTreeNode.getId()) {
MultiTreeNode child = new MultiTreeNode(temp.getId(),
temp.getName());
List children = multiTreeNode.getChildren();
if (children == null) {
children = new ArrayList<>();
multiTreeNode.setChildren(children);
}
children.add(child);
setChildren(child);
}
}
}
} ToSingleTreeTransformer：
package com.zzj.tree;
import java.util.ArrayList;
import java.util.List;
public class ToSingleTreeTransformer {
private List multiTreeNodes;
private List singleTreeNodes = new ArrayList<>();
public ToSingleTreeTransformer(List multiTreeNodes) {
this.multiTreeNodes = multiTreeNodes;
}
public List transform(){
// 先获取根节点
for (int i = 0; i < multiTreeNodes.size(); i++) {
MultiTreeNode multiTreeNode = multiTreeNodes.get(i);
SingleTreeNode singleTreeNode = new SingleTreeNode(multiTreeNode.getId(),
0, multiTreeNode.getName());
singleTreeNodes.add(singleTreeNode);
}
// 获取子节点
for (int i = 0; i < multiTreeNodes.size(); i++) {
MultiTreeNode multiTreeNode = multiTreeNodes.get(i);
getChildren(multiTreeNode);
}
return singleTreeNodes;
}
/**
* 获取子节点
* @param multiTreeNode
*/
private void getChildren(MultiTreeNode multiTreeNode){
for (int i = 0; i < singleTreeNodes.size(); i++) {
SingleTreeNode temp = singleTreeNodes.get(i);
if (multiTreeNode.getId() == temp.getId()) {
List children = multiTreeNode.getChildren();
if (children != null) {
for (int j = 0; j < children.size(); j++) {
MultiTreeNode child = children.get(j);
SingleTreeNode singleTreeNode = new SingleTreeNode(child.getId(),
multiTreeNode.getId(), child.getName());
singleTreeNodes.add(singleTreeNode);
getChildren(child);
}
}
}
}
}
} 测试
package com.zzj.tree;
import java.util.ArrayList;
import java.util.List;
public class TreeTransformerTest {
private final static List SINGLE_TREE = new ArrayList();
static {
SingleTreeNode China = new SingleTreeNode(1, 0, "中国");
SINGLE_TREE.add(China);
SingleTreeNode Hunan = new SingleTreeNode(2, 1, "湖南");
SINGLE_TREE.add(Hunan);
SingleTreeNode Changsha = new SingleTreeNode(3, 2, "长沙");
SINGLE_TREE.add(Changsha);
SingleTreeNode Hubei = new SingleTreeNode(4, 1, "湖北");
SINGLE_TREE.add(Hubei);
SingleTreeNode Wuhan = new SingleTreeNode(5, 4, "武汉");
SINGLE_TREE.add(Wuhan);
SingleTreeNode America = new SingleTreeNode(6, 0, "美国");
SINGLE_TREE.add(America);
SingleTreeNode California = new SingleTreeNode(7, 6, "加利福尼亚");
SINGLE_TREE.add(California);
SingleTreeNode LosAngeles = new SingleTreeNode(8, 7, "洛杉矶");
SINGLE_TREE.add(LosAngeles);
}
public static void main(String[] args) throws Exception {
ToMultiTreeTransformer multiTreeTransformer = new ToMultiTreeTransformer(SINGLE_TREE);
List multiTreeNodes = multiTreeTransformer.transform();
System.out.println(multiTreeNodes);
ToSingleTreeTransformer singleTreeTransformer = new ToSingleTreeTransformer(multiTreeNodes);
List singleTreeNodes = singleTreeTransformer.transform();
System.out.println(singleTreeNodes);
}
} 输出结果：
[MultiTreeNode [id=1, name=中国, children=[MultiTreeNode [id=2, name=湖南, children=[MultiTreeNode [id=3, name=长沙, children=null]]], MultiTreeNode [id=4, name=湖北, children=[MultiTreeNode [id=5, name=武汉, children=null]]]]], MultiTreeNode [id=6, name=美国, children=[MultiTreeNode [id=7, name=加利福尼亚, children=[MultiTreeNode [id=8, name=洛杉矶, children=null]]]]]] [SingleTreeNode [id=1, pId=0, name=中国], SingleTreeNode [id=6, pId=0, name=美国], SingleTreeNode [id=2, pId=1, name=湖南], SingleTreeNode [id=3, pId=2, name=长沙], SingleTreeNode [id=4, pId=1, name=湖北], SingleTreeNode [id=5, pId=4, name=武汉], SingleTreeNode [id=7, pId=6, name=加利福尼亚], SingleTreeNode [id=8, pId=7, name=洛杉矶]]
总结
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