java实现递归菜单树

本文实例为大家分享了java实现递归菜单树的具体代码，供大家参考，具体内容如下

1.表结构

SET FOREIGN_KEY_CHECKS=0;

-- ----------------------------
-- Table structure for menu
-- ----------------------------
DROP TABLE IF EXISTS `menu`;
CREATE TABLE `menu` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`menu_name` varchar(64) NOT NULL COMMENT '菜单名称',
`order_num` int(11) DEFAULT NULL COMMENT '菜单顺序',
`url` varchar(64) DEFAULT NULL COMMENT '菜单路径',
`pid` varchar(11) DEFAULT NULL COMMENT '上级Id',
`icon` varchar(255) DEFAULT NULL COMMENT '菜单图标',
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=11 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of menu
-- ----------------------------
INSERT INTO `menu` VALUES ('1', '系统管理', '1', '', '0', null);
INSERT INTO `menu` VALUES ('2', '轨迹查询', '2', '', '0', null);
INSERT INTO `menu` VALUES ('3', '设备信息', '3', '', '0', null);
INSERT INTO `menu` VALUES ('4', '用户信息', '1', '', '1', null);
INSERT INTO `menu` VALUES ('5', '客户信息', '2', null, '1', null);
INSERT INTO `menu` VALUES ('6', '用户资料', '1', null, '4', null);
INSERT INTO `menu` VALUES ('7', '客户资料', '1', null, '5', null);
INSERT INTO `menu` VALUES ('8', '切割机', '1', null, '3', null);
INSERT INTO `menu` VALUES ('9', '铲车', '2', null, '3', null);
INSERT INTO `menu` VALUES ('10', '割片', '1', null, '8', null);

2.菜单实体类

import lombok.Data;
import java.io.Serializable;
import java.util.List;
import javax.persistence.*;

/**
*
* @author m
* @email 123456789@qq.com
* @date 2019-12-13 16:54:59
*/
@Data
@Table(name = "menu")
public class Menu implements Serializable {
private static final long serialVersionUID = 1L;

//
@Id
private Integer id;

//菜单名称
@Column(name = "menu_name")
private String menuName;

//菜单顺序
@Column(name = "order_num")
private Integer orderNum;

//菜单路径
@Column(name = "url")
private String url;

//上级Id
@Column(name = "pid")
private String pid;

//菜单图标
@Column(name = "icon")
private String icon;

//子菜单
@Transient
private List<Menu> children;

}

3.菜单树

/**
 * 获取菜单树
 * @return
 */
public List<Menu> menuTree() {
 //查询所有菜单
 List<Menu> menus = mapper.selectAll();
 //返回的菜单树
 List<Menu> rootMenus = new ArrayList<>();
 for (Menu menu : menus) {
  //pid（上级Id）为0的是根菜单
  if ("0".equals(menu.getPid())) {
   rootMenus.add(menu);
  }
 }
 //遍历，找到二级菜单（根菜单的id和所有菜单中的pid比较）
 for (Menu rootMenu : rootMenus) {
  List<Menu> child = getChild(String.valueOf(rootMenu.getId()), menus);
  rootMenu.setChildren(child);
 }
 return rootMenus;
}

/**
 * 递归获取下级菜单
 * @param pid 上级Id
 * @param menus 所有菜单
 * @return
 */
public List<Menu> getChild(String pid, List<Menu> menus) {
 //子菜单列表
 List<Menu> childList = new ArrayList<>();
 for (Menu menu : menus) {
  if (pid.equals(menu.getPid())) {
   childList.add(menu);
  }
 }
 //遍历 获取子菜单的子菜单
 for (Menu menu : childList) {
  List<Menu> child = getChild(String.valueOf(menu.getId()), menus);
  menu.setChildren(child);
 }
 //递归出口 childList长度为0
 if (childList.size() == 0) {
  return new ArrayList<>();
 }
 return childList;
}

4.测试

{
"status": 200,
"message": "操作成功",
"data": [
 {
  "id": 1,
  "menuName": "系统管理",
  "orderNum": 1,
  "url": "",
  "pid": "0",
  "icon": null,
  "children": [
   {
    "id": 4,
    "menuName": "用户信息",
    "orderNum": 1,
    "url": "",
    "pid": "1",
    "icon": null,
    "children": [
     {
      "id": 6,
      "menuName": "用户资料",
      "orderNum": 1,
      "url": null,
      "pid": "4",
      "icon": null,
      "children": []
     }
    ]
   },
   {
    "id": 5,
    "menuName": "客户信息",
    "orderNum": 2,
    "url": null,
    "pid": "1",
    "icon": null,
    "children": [
     {
      "id": 7,
      "menuName": "客户资料",
      "orderNum": 1,
      "url": null,
      "pid": "5",
      "icon": null,
      "children": []
     }
    ]
   }
  ]
 },
 {
  "id": 2,
  "menuName": "轨迹查询",
  "orderNum": 2,
  "url": "",
  "pid": "0",
  "icon": null,
  "children": []
 },
 {
  "id": 3,
  "menuName": "设备信息",
  "orderNum": 3,
  "url": "",
  "pid": "0",
  "icon": null,
  "children": [
   {
    "id": 8,
    "menuName": "切割机",
    "orderNum": 1,
    "url": null,
    "pid": "3",
    "icon": null,
    "children": [
     {
      "id": 10,
      "menuName": "割片",
      "orderNum": 1,
      "url": null,
      "pid": "8",
      "icon": null,
      "children": []
     }
    ]
   },
   {
    "id": 9,
    "menuName": "铲车",
    "orderNum": 2,
    "url": null,
    "pid": "3",
    "icon": null,
    "children": []
   }
  ]
 }
]
}

5.菜单树工具类

菜单树工具类

来源：https://blog.csdn.net/weixin_42740530/article/details/103564528