Java从数据库读取页面树形菜单

从数据库加载菜单及子菜单主要使用递归的方法，具体实现可看代码

首先封装一个菜单pojo

public class Menu {

    // 菜单id

    private String id;

    // 菜单名称

    private String name;

    // 父菜单id

    private String parentId;

    // 菜单url

    private String url;

    // 菜单图标

    private String icon;

    // 菜单顺序

    private int order;

    // 子菜单

    private List<Menu> childMenus;

    public String getId() {

        return id;

    }

    public void setId(String id) {

        this.id = id;

    }

    public String getName() {

        return name;

    }

    public void setName(String name) {

        this.name = name;

    }

    public String getParentId() {

        return parentId;

    }

    public void setParentId(String parentId) {

        this.parentId = parentId;

    }

    public String getUrl() {

        return url;

    }

    public void setUrl(String url) {

        this.url = url;

    }

    public String getIcon() {

        return icon;

    }

    public void setIcon(String icon) {

        this.icon = icon;

    }

    public int getOrder() {

        return order;

    }

    public void setOrder(int order) {

        this.order = order;

    }

    public List<Menu> getChildMenus() {

        return childMenus;

    }

    public void setChildMenus(List<Menu> childMenus) {

        this.childMenus = childMenus;

    }

}

　　然后写dao接口

package com.xfma.dao;

import com.xfma.pojo.Menu;

import java.util.List;

public interface MenuMapper {

    /**

     * 查找用户的菜单

     * @return

     */

    public List<Menu> queryMenuList();

}

　　接着mybatis配置映射文件

<?xml version="1.0" encoding="UTF-8" ?>

<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >

<mapper namespace="com.xfma.dao.MenuMapper" >

    <select id="queryMenuList" resultType="com.xfma.pojo.Menu">

        SELECT

            id,`name`,parent_id as parentId,url,icon,`order`

        FROM

            jrbac_menu ORDER BY `order` ASC

    </select>

</mapper>

　　接下来是service接口

package com.xfma.service;

import com.xfma.pojo.Menu;

import java.util.List;

public interface IMenuService {

    public List<Menu> listMenu();

}

　　service实现类

package com.xfma.service.impl;

import com.xfma.dao.MenuMapper;

import com.xfma.pojo.Menu;

import com.xfma.service.IMenuService;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Service;

import org.springframework.util.StringUtils;

import java.util.ArrayList;

import java.util.List;

@Service

public class MenuService implements IMenuService {

    @Autowired

    private MenuMapper menuMapper;

    public List<Menu> listMenu() {

        List<Menu> rootMenus = menuMapper.queryMenuList();

        List<Menu> list = getMenuList(rootMenus);

        return list;

    }

    /**

     * 找出一级菜单和二级菜单

     * @param rootMenus

     * @return

     */

    private List<Menu> getMenuList(List<Menu> rootMenus){

        List<Menu> list = new ArrayList<Menu>();

        // 先找到所有的一级菜单

        for (int i=0;i<rootMenus.size();i++){

            Menu menu = rootMenus.get(i);

            //一级菜单  没有父节点

            if (StringUtils.isEmpty(menu.getParentId())){

                list.add(menu);

            }

        }

        //查找二级菜单

        /**

         * 利用递归找出所有子菜单

         */

        for (Menu menu: list) {

            menu.setChildMenus(getChild(menu.getId(),rootMenus));

        }

        return list;

    }

    /**

     * 找出子菜单

     * @param id

     * @param rootMenu

     * @return

     */

    private List<Menu> getChild(String id, List<Menu> rootMenu) {

        // 子菜单

        List<Menu> childList = new ArrayList<Menu>();

        for (Menu menu : rootMenu) {

            // 遍历所有节点，将父菜单id与传过来的id比较

            if (!StringUtils.isEmpty(menu.getParentId())) {

                if (menu.getParentId().equals(id)) {

                    childList.add(menu);

                }

            }

        }

        // 把子菜单的子菜单再循环一遍

        for (Menu menu : childList) {// 没有url子菜单还有子菜单

            if (StringUtils.isEmpty(menu.getUrl())) {

                // 递归

                menu.setChildMenus(getChild(menu.getId(), rootMenu));

            }

        }

        // 递归退出条件

        if (childList.size() == 0) {

            return null;

        }

        return childList;

    }

}

　　返回的结果是已经封装好的各个菜单和子菜单，只需前台遍历就可以了。

下面附上SQL脚本：

DROP TABLE IF EXISTS `jrbac_menu`;

CREATE TABLE `jrbac_menu` (

  `id` varchar(32) NOT NULL COMMENT '主键id,uuid32位',

  `name` varchar(64) NOT NULL COMMENT '登录用户名',

  `parent_id` varchar(32) default NULL COMMENT '父菜单id',

  `url` varchar(64) default NULL COMMENT '访问地址',

  `icon` varchar(32) default NULL COMMENT '菜单图标',

  `order` tinyint(4) default '0' COMMENT '菜单顺序',

  PRIMARY KEY  (`id`)

) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='菜单表';

-- ----------------------------

-- Records of jrbac_menu

-- ----------------------------

INSERT INTO `jrbac_menu` VALUES ('1', 'Forms', null, 'forms.html', 'fa fa-edit', '0');

INSERT INTO `jrbac_menu` VALUES ('2', 'UI Elements', null, '', 'fa fa-wrench', '1');

INSERT INTO `jrbac_menu` VALUES ('3', 'Buttons', '2', 'buttons.html', '', '0');

INSERT INTO `jrbac_menu` VALUES ('4', 'Icons', '2', 'icons.html', null, '1');

INSERT INTO `jrbac_menu` VALUES ('5', 'Multi-Level Dropdown', '', '', 'fa fa-sitemap', '2');

INSERT INTO `jrbac_menu` VALUES ('6', 'Second Level Item', '5', 'second.html', null, '0');

INSERT INTO `jrbac_menu` VALUES ('7', 'Third Level', '5', null, '', '1');

INSERT INTO `jrbac_menu` VALUES ('8', 'Third Level Item', '7', 'third.html', null, '0');

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Java从数据库读取页面树形菜单

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