本文转载自：https://www.cnblogs.com/lucky-pin/p/10740037.html
这篇文章写得很好，解决了我的一个需求问题。
递归生成一个如图的菜单，编写两个类数据模型Menu、和创建树形的MenuTree。通过以下过程实现：
1.首先从菜单数据中获取所有根节点。
2.为根节点建立次级子树并拼接上。
3.递归为子节点建立次级子树并接上，直至为末端节点拼接上空的”树”。
首先，编写数据模型Menu。每条菜单有自己的id、父节点parentId、菜单名称text、菜单还拥有次级菜单children。
import java.util.List;
public class Menu {
private String id;
private String parentId;
private String text;
private String url;
private String yxbz;
private List children;
public Menu(String id,String parentId,String text,String url,String yxbz) {
this.id=id;
this.parentId=parentId;
this.text=text;
this.url=url;
this.yxbz=yxbz;
}
/*省略get\set*/
}
创建树形结构的类MenuTree。方法getRootNode获取所有根节点，方法builTree将根节点汇总创建树形结构，buildChilTree为节点建立次级树并拼接上当前树，递归调用buildChilTree不断为当前树开枝散叶直至找不到新的子树。完成递归，获取树形结构。
import java.util.ArrayList;
import java.util.List;
public class MenuTree {
private List menuList = new ArrayList();
public MenuTree(List menuList) {
this.menuList=menuList;
}
//建立树形结构
public List builTree(){
List treeMenus =new ArrayList();
for(Menu menuNode : getRootNode()) {
menuNode=buildChilTree(menuNode);
treeMenus.add(menuNode);
}
return treeMenus;
}
//递归，建立子树形结构
private Menu buildChilTree(Menu pNode){
List chilMenus =new ArrayList();
for(Menu menuNode : menuList) {
if(menuNode.getParentId().equals(pNode.getId())) {
chilMenus.add(buildChilTree(menuNode));
}
}
pNode.setChildren(chilMenus);
return pNode;
}
//获取根节点
private List getRootNode() {
List rootMenuLists =new ArrayList();
for(Menu menuNode : menuList) {
if(menuNode.getParentId().equals("0")) {
rootMenuLists.add(menuNode);
}
}
return rootMenuLists;
}
}
最后，插入一些数据试试效果。得到的json就可以生成图一菜单了。
import java.util.ArrayList;
import java.util.List;
import com.alibaba.fastjson.JSON;
public class Hello {
public static void main(String []args) {
List menuList= new ArrayList();
/*插入一些数据*/
menuList.add(new Menu("GN001D000","0","系统管理","/admin","Y"));
menuList.add(new Menu("GN001D100","GN001D000","权限管理","/admin","Y"));
menuList.add(new Menu("GN001D110","GN001D100","密码修改","/admin","Y"));
menuList.add(new Menu("GN001D120","GN001D100","新加用户","/admin","Y"));
menuList.add(new Menu("GN001D200","GN001D000","系统监控","/admin","Y"));
menuList.add(new Menu("GN001D210","GN001D200","在线用户","/admin","Y"));
menuList.add(new Menu("GN002D000","0","订阅区","/admin","Y"));
menuList.add(new Menu("GN003D000","0","未知领域","/admin","Y"));
/*让我们创建树*/
MenuTree menuTree =new MenuTree(menuList);
menuList=menuTree.builTree();
/*转为json看看效果*/
String jsonOutput= JSON.toJSONString(menuList);
System.out.println(jsonOutput);
}
}
Original: https://www.cnblogs.com/miaoying/p/14804670.html
Author: miaoying
Title: JAVA递归生成树形菜单
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