一、数据分析

我们可以知道一级菜单都是放在ul下面的li标签中的a标签，我们是不是可以放在同一级别进行遍历，而子级菜单都是为dd标签中，所以我们可以放在一起进行遍历。

数据格式：

[
{name:会议管理，children:[
{name:发布会议},
{name:我的会议},
{name:会议通知},
{name:历史会议}
]},
{name:menu group2},
{name:click menu item},
{name:the links}
]

二、获取数据库中的所有菜单数据

表格数据：

首先，先建立一个实体类名为Permission

package com.zking.entity;
/**
 * 数据库中t_oa_Permission表对应的实体类
 * @author Administrator
 *
 */
public class Permission {
	private long id;
	private String name;//菜单名字
	private String description;//菜单描述
	private String url;//点击菜单跳转的页面
	private long pid;//父级菜单id
	private int ismenu;//菜单/按钮
	private long displayno;//显示的顺序
	public long getId() {
		return id;
	}
	public void setId(long id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getDescription() {
		return description;
	}
	public void setDescription(String description) {
		this.description = description;
	}
	public String getUrl() {
		return url;
	}
	public void setUrl(String url) {
		this.url = url;
	}
	public long getPid() {
		return pid;
	}
	public void setPid(long pid) {
		this.pid = pid;
	}
	public int getIsmenu() {
		return ismenu;
	}
	public void setIsmenu(int ismenu) {
		this.ismenu = ismenu;
	}
	public long getDisplayno() {
		return displayno;
	}
	public void setDisplayno(long displayno) {
		this.displayno = displayno;
	}
	public Permission(long id, String name, String description, String url, long pid, int ismenu, long displayno) {
		super();
		this.id = id;
		this.name = name;
		this.description = description;
		this.url = url;
		this.pid = pid;
		this.ismenu = ismenu;
		this.displayno = displayno;
	}
	public Permission() {
		// TODO Auto-generated constructor stub
	}
	@Override
	public String toString() {
		return "Permission [id=" + id + ", name=" + name + ", description=" + description + ", url=" + url + ", pid="
				+ pid + ", ismenu=" + ismenu + ", displayno=" + displayno + "]";
	}
	
}

写一个dao方法：MenuDao

package com.zking.dao;

import java.util.List;

import com.zking.entity.Permission;
import com.zking.util.BaseDao;
import com.zking.util.PageBean;

public class MenuDao extends BaseDao<Permission>{
	
	//查询t_oa_permission表中的数据
	public List<Permission> executeQuery(Permission permission, PageBean pageBean) throws Exception {
		String sql="SELECT * from t_oa_permission";
		return super.executeQuery(sql, Permission.class, pageBean);
	}
}

运行结果：

三、将菜单表中的数据在后台构建父子关系

将数据转为Json格式

package com.zking.dao;
 
import static org.junit.Assert.*;
 
import java.util.List;
 
import org.junit.Test;
 
import com.fasterxml.jackson.databind.ObjectMapper;
import com.zking.entity.Permission;
 
public class PermissionDaoTest {
 
	private PermissionDao pd = new PermissionDao();
	
	@Test
	public void testList() {
		try {
			List<Permission> list = pd.list(null,null);
			for (Permission permission : list) {
				//System.out.println(permission);
			}
			ObjectMapper om = new ObjectMapper();
			System.out.println(om.writeValueAsString(list));
		
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
 
}

得到Json数据：

[{
   "id": 10,
   "name": "会议管理",
   "description": null,
   "url": null,
   "pid": -1,
   "ismenu": 1,
   "displayno": 1
}, {
   "id": 11,
   "name": "投票管理",
   "description": null,
   "url": null,
   "pid": -1,
   "ismenu": 1,
   "displayno": 9
}, {
   "id": 12,
   "name": "会议室管理",
   "description": null,
   "url": "jsp/meeting/meetingRoom.jsp",
   "pid": -1,
   "ismenu": 1,
   "displayno": 14
}, {
   "id": 13,
   "name": "系统管理",
   "description": null,
   "url": null,
   "pid": -1,
   "ismenu": 1,
   "displayno": 15
}, {
   "id": 1001,
   "name": "会议发布",
   "description": "发起会议",
   "url": "jsp/meeting/addMeeting.jsp",
   "pid": 10,
   "ismenu": 1,
   "displayno": 2
}, {
   "id": 1002,
   "name": "会议通知",
   "description": "别人发起的会议，需要你确认是否参加",
   "url": "jsp/meeting/meetingNotify.jsp",
   "pid": 10,
   "ismenu": 1,
   "displayno": 3
}, {
   "id": 1003,
   "name": "我的会议",
   "description": "我发起的，未审核->已审核",
   "url": "jsp/meeting/myMeeting.jsp",
   "pid": 10,
   "ismenu": 1,
   "displayno": 4
}, {
   "id": 1004,
   "name": "我的审批",
   "description": "我审批的会议",
   "url": "jsp/meeting/myAudit.jsp",
   "pid": 10,
   "ismenu": 1,
   "displayno": 5
}, {
   "id": 1005,
   "name": "待开会议",
   "description": "我参与的，但是还未开始的",
   "url": "jsp/meeting/meetingWaiting.jsp",
   "pid": 10,
   "ismenu": 1,
   "displayno": 6
}, {
   "id": 1006,
   "name": "历史会议",
   "description": "已经参与的",
   "url": "jsp/meeting/meetingHistory.jsp",
   "pid": 10,
   "ismenu": 1,
   "displayno": 7
}, {
   "id": 1007,
   "name": "所有会议",
   "description": "对所有会议进行汇总",
   "url": "jsp/meeting/meetingAll.jsp",
   "pid": 10,
   "ismenu": 1,
   "displayno": 8
}, {
   "id": 1101,
   "name": "投票标题",
   "description": "需要关联到会议标题（议题）",
   "url": null,
   "pid": 11,
   "ismenu": 1,
   "displayno": 10
}, {
   "id": 1102,
   "name": "投票选项",
   "description": "需要关联到投票标题",
   "url": null,
   "pid": 11,
   "ismenu": 1,
   "displayno": 11
}, {
   "id": 1103,
   "name": "投票结果",
   "description": "需要保留数据，可以看到谁投了什么票",
   "url": null,
   "pid": 11,
   "ismenu": 1,
   "displayno": 12
}, {
   "id": 1104,
   "name": "投票报表",
   "description": "哪标题的哪个选项共投了多少票",
   "url": null,
   "pid": 11,
   "ismenu": 1,
   "displayno": 13
}, {
   "id": 1301,
   "name": "用户管理",
   "description": null,
   "url": "jsp/system/userManage.jsp",
   "pid": 13,
   "ismenu": 1,
   "displayno": 16
}, {
   "id": 1302,
   "name": "角色管理",
   "description": null,
   "url": null,
   "pid": 13,
   "ismenu": 1,
   "displayno": 17
}, {
   "id": 1303,
   "name": "权限管理",
   "description": null,
   "url": null,
   "pid": 13,
   "ismenu": 1,
   "displayno": 18
}, {
   "id": 1304,
   "name": "数据字典",
   "description": null,
   "url": null,
   "pid": 13,
   "ismenu": 1,
   "displayno": 19
}]

我们根据以上Json数据可以知道，数据中还没有形成父子关系，现在我们就需要缔造父子关系，借用工具类

package com.zking.util;
 
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
 
public class BuildTree {
 
	/**
	 * 默认-1为顶级节点
	 * @param nodes
	 * @param <T>
	 * @return
	 */
	public static <T> TreeVo<T> build(List<TreeVo<T>> nodes) {
 
		if (nodes == null) {
			return null;
		}
		List<TreeVo<T>> topNodes = new ArrayList<TreeVo<T>>();
 
		for (TreeVo<T> children : nodes) {
			String pid = children.getParentId();
			if (pid == null || "-1".equals(pid)) {
				topNodes.add(children);
 
				continue;
			}
 
			for (TreeVo<T> parent : nodes) {
				String id = parent.getId();
				if (id != null && id.equals(pid)) {
					parent.getChildren().add(children);
					children.setHasParent(true);
					parent.setChildren(true);
					continue;
				}
			}
 
		}
 
		TreeVo<T> root = new TreeVo<T>();
		if (topNodes.size() == 1) {
			root = topNodes.get(0);
		} else {
			root.setId("000");
			root.setParentId("-1");
			root.setHasParent(false);
			root.setChildren(true);
			root.setChecked(true);
			root.setChildren(topNodes);
			root.setText("顶级节点");
			Map<String, Object> state = new HashMap<>(16);
			state.put("opened", true);
			root.setState(state);
		}
 
		return root;
	}
 
	/**
	 * 指定idparam为顶级节点
	 * @param nodes
	 * @param idParam
	 * @param <T>
	 * @return
	 */
	public static <T> List<TreeVo<T>> buildList(List<TreeVo<T>> nodes, String idParam) {
		if (nodes == null) {
			return null;
		}
		List<TreeVo<T>> topNodes = new ArrayList<TreeVo<T>>();
 
		for (TreeVo<T> children : nodes) {
 
			String pid = children.getParentId();
			if (pid == null || idParam.equals(pid)) {
				topNodes.add(children);
 
				continue;
			}
 
			for (TreeVo<T> parent : nodes) {
				String id = parent.getId();
				if (id != null && id.equals(pid)) {
					parent.getChildren().add(children);
					children.setHasParent(true);
					parent.setChildren(true);
 
					continue;
				}
			}
 
		}
		return topNodes;
	}
 
}

在MenuDao中调用

package com.zking.dao;

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

import com.zking.entity.Permission;
import com.zking.util.BaseDao;
import com.zking.util.BuildTree;
import com.zking.util.PageBean;
import com.zking.util.TreeVo;

public class MenuDao extends BaseDao<Permission>{
	
	//查询t_oa_permission表中的数据
	public List<Permission> executeQuery(Permission permission, PageBean pageBean) throws Exception {
		String sql="SELECT * from t_oa_permission";
		return super.executeQuery(sql, Permission.class, pageBean);
	}
	
	public List<TreeVo<Permission>> menus(Permission permission, PageBean pageBean) throws Exception {
		List<TreeVo<Permission>> trees=new ArrayList<TreeVo<Permission>>();
		//从数据库中拿到的菜单数据，此时数据都是平级的，不具备父子关系
		List<Permission> list = this.executeQuery(permission, pageBean);
		for (Permission p : list) {
			TreeVo<Permission> vo=new TreeVo<>();
			vo.setId(p.getId()+"");
			vo.setText(p.getName());//节点的名字
			vo.setParentId(p.getPid()+"");
			trees.add(vo);
		}
		return BuildTree.buildList(trees, "-1");
	}
}

在测试类中调用 :MenuDaoTest

package com.zking.dao;

import static org.junit.jupiter.api.Assertions.*;

import java.util.List;

import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.zking.entity.Permission;
import com.zking.util.TreeVo;

class MenuDaoTest {
	private MenuDao menuDao=new MenuDao();
	
	@BeforeEach
	void setUp() throws Exception {
	}

	@AfterEach
	void tearDown() throws Exception {
	}

	@Test
	void testExecuteQueryPermissionPageBean() {
		try {
			List<Permission> list = menuDao.executeQuery(null, null);
			for (Permission permission : list) {
				System.out.println(permission);
			}
			ObjectMapper om=new ObjectMapper();
			System.out.println(om.writeValueAsString(list));
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	
	@Test
	void testMenus() {
		try {
			List<TreeVo<Permission>> list = menuDao.menus(null, null);
			for (TreeVo<Permission> treeVo : list) {
				System.out.println(treeVo);
			}
			ObjectMapper om=new ObjectMapper();
			System.out.println(om.writeValueAsString(list));
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}

效果：

四、前端代码实现

写web层

PermissionAction ：

package com.zking.web;

import java.util.List;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.zking.dao.PermissionDao;
import com.zking.entity.Permission;
import com.zking.framework.ActionSupport;
import com.zking.framework.ModelDriver;
import com.zking.util.ResponseUtil;
import com.zking.util.TreeVo;

public class PermissionAction extends ActionSupport implements ModelDriver<Permission>{
	private Permission permission=new Permission();
	private PermissionDao permissionDao= new PermissionDao();
	@Override
	public Permission getModel() {
		// TODO Auto-generated method stub
		return permission;
	}
	
	public String menus(HttpServletRequest req, HttpServletResponse resp) {
		try {
			List<TreeVo<Permission>> menus = permissionDao.menus(null,null);
			//向前端响应树型结构
			ResponseUtil.writeJson(resp, menus);
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return null;
	}
}

mvc.xml:

<?xml version="1.0" encoding="UTF-8"?>
<config>
	<action path="/blog" type="com.zking.web.BlogAction">
		<forward name="list" path="/blogList.jsp" redirect="false" />
		<forward name="toList" path="/blog.action?methodName=list"
			redirect="true" />
		<forward name="toEdit" path="/blogEdit.jsp" redirect="false" />
	</action>


	<action path="/user" type="com.zking.web.UserAction">
	</action>

	<action path="/permission" type="com.zking.web.PermissionAction">
	</action>	
</config>

前端代码：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
    <%@ include file="common/header.jsp" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<div class="layui-layout layui-layout-admin">
  <div class="layui-header">
    <div class="layui-logo layui-hide-xs layui-bg-black">layout demo</div>
    <!-- 头部区域（可配合layui 已有的水平导航） -->
    <ul class="layui-nav layui-layout-left">
      <!-- 移动端显示 -->
      <li class="layui-nav-item layui-show-xs-inline-block layui-hide-sm" lay-header-event="menuLeft">
        <i class="layui-icon layui-icon-spread-left"></i>
      </li>
      <!-- Top导航栏 -->
      <li class="layui-nav-item layui-hide-xs"><a href="">nav 1</a></li>
      <li class="layui-nav-item layui-hide-xs"><a href="">nav 2</a></li>
      <li class="layui-nav-item layui-hide-xs"><a href="">nav 3</a></li>
      <li class="layui-nav-item">
        <a href="javascript:;">nav groups</a>
        <dl class="layui-nav-child">
          <dd><a href="">menu 11</a></dd>
          <dd><a href="">menu 22</a></dd>
          <dd><a href="">menu 33</a></dd>
        </dl>
      </li>
    </ul>
    <!-- 个人头像及账号操作 -->
    <ul class="layui-nav layui-layout-right">
      <li class="layui-nav-item layui-hide layui-show-md-inline-block">
        <a href="javascript:;">
          <img src="//tva1.sinaimg.cn/crop.0.0.118.118.180/5db11ff4gw1e77d3nqrv8j203b03cweg.jpg" class="layui-nav-img">
          tester
        </a>
        <dl class="layui-nav-child">
          <dd><a href="">Your Profile</a></dd>
          <dd><a href="">Settings</a></dd>
          <dd><a href="login.jsp">Sign out</a></dd>
        </dl>
      </li>
      <li class="layui-nav-item" lay-header-event="menuRight" lay-unselect>
        <a href="javascript:;">
          <i class="layui-icon layui-icon-more-vertical"></i>
        </a>
      </li>
    </ul>
  </div>
  
  <div class="layui-side layui-bg-black">
    <div class="layui-side-scroll">
      <!-- 左侧导航区域（可配合layui已有的垂直导航） -->
      <ul id="menu" class="layui-nav layui-nav-tree" lay-filter="menu">
        <li class="layui-nav-item layui-nav-itemed">
          <a class="" href="javascript:;">会议管理1</a>
          <dl class="layui-nav-child">
            <dd><a href="javascript:;">发布会议</a></dd>
            <dd><a href="javascript:;">我的会议</a></dd>
            <dd><a href="javascript:;">会议通知</a></dd>
            <dd><a href="">历史会议</a></dd>
          </dl>
        </li>
        <li class="layui-nav-item">
          <a href="javascript:;">menu group 2</a>
          <dl class="layui-nav-child">
            <dd><a href="javascript:;">list 1</a></dd>
            <dd><a href="javascript:;">list 2</a></dd>
            <dd><a href="">超链接</a></dd>
          </dl>
        </li>
        <li class="layui-nav-item"><a href="javascript:;">click menu item</a></li>
        <li class="layui-nav-item"><a href="">the links</a></li> 
      </ul>
    </div>
  </div>
  
  <div class="layui-body">
    <!-- 内容主体区域 -->
    <div style="padding: 15px;">内容主体区域。记得修改 layui.css 和 js 的路径</div>
  </div>
  
  <div class="layui-footer">
    <!-- 底部固定区域 -->
            底部固定区域
  </div>
</div>
<script>
layui.use(['jquery'],function(){
	let $ = layui.jquery;
	$.ajax({
		url:'${pageContext.request.contextPath}//permission.action?methodName=menus'
		,dataType:'json'
		,success:function(data){
			//console.log(data);
			let htmlstr = '';
			$.each(data,function(i,n){
				htmlstr +='<li class="layui-nav-item layui-nav-itemed">';
				htmlstr +='		<a class="" href="javascript:;">'+data[i].text+'</a>';
				//判断当前一及节点是否存在子节点
				if(data[i].hasChildren){
					htmlstr += ' <dl class="layui-nav-child">';
					let children = data[i].children;
					$.each(children,function(index,node){
						htmlstr += '<dd><a href="javascript:;">'+children[index].text+'</a></dd>';
					});
					htmlstr += '</dl>';
				}
				
				htmlstr +='</li>';
			});
			$("#menu").html(htmlstr);
		}
	});
	
});
 
</script>
</body>
</html>

效果：

原文链接：https://blog.csdn.net/m0_62604616/article/details/125669388