How to implement menu tree recursively in Java-javaTutorial-php.cn

How to implement menu tree recursively in Java

pom file

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <!--  可选修改：之前的一些案例按照此版本搭建      -->
        <version>2.1.3.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>demo</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <!--  spring boot 整合mybatis的核心依赖-->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.1.1</version>
        </dependency>
        <!--        数据库驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <!--pageHelper分页插件-->
        <dependency>
            <groupId>com.github.pagehelper</groupId>
            <artifactId>pagehelper-spring-boot-starter</artifactId>
            <version>1.3.0</version>
        </dependency>
        <!-- 引入lombok，简化pojo类-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <!--        引入Mybatis plus 依赖  增强mybatis-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.2</version>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

Copy after login

application.yaml file

spring:
  datasource:   
    url: jdbc:mysql://localhost:3306/springboot?useUnicode=true&characterEncoding=utf-8&serverTimezone=CTT
    username: root
    password: 2020
    driver-class-name: com.mysql.cj.jdbc.Driver
pagehelper:
  helperDialect: mysql
  reasonable: true # 修改默认值
# mybatis-plus配置
mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
  typeAliasesPackage: com.qcby.entity
  mapperLocations: classpath:mapper/*.xml
  # 全局配置id自增  =>
  global-config:
    db-config:
      id-type: auto

Copy after login

Database table design As follows

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;
-- ----------------------------
-- Table structure for menu
-- ----------------------------
DROP TABLE IF EXISTS `menu`;
CREATE TABLE `menu`  (
  `id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT &#39;主键id&#39;,
  `name` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_bin DEFAULT NULL COMMENT &#39;名称&#39;,
  `pid` bigint(20) DEFAULT NULL COMMENT &#39;父级id&#39;,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 10 CHARACTER SET = utf8mb4 COLLATE = utf8mb4_bin ROW_FORMAT = Compact;
-- ----------------------------
-- Records of menu
-- ----------------------------
INSERT INTO `menu` VALUES (1, &#39;主菜单1&#39;, 0);
INSERT INTO `menu` VALUES (2, &#39;主菜单2&#39;, 0);
INSERT INTO `menu` VALUES (3, &#39;主菜单3&#39;, 0);
INSERT INTO `menu` VALUES (4, &#39;菜单1.1&#39;, 1);
INSERT INTO `menu` VALUES (5, &#39;菜单1.2&#39;, 1);
INSERT INTO `menu` VALUES (6, &#39;菜单1.1.1&#39;, 4);
INSERT INTO `menu` VALUES (7, &#39;菜单2.1&#39;, 2);
INSERT INTO `menu` VALUES (8, &#39;菜单2.2&#39;, 2);
INSERT INTO `menu` VALUES (9, &#39;菜单1.1.2&#39;, 4);
SET FOREIGN_KEY_CHECKS = 1;

Copy after login

Menu class

package com.qcby.entity;
import lombok.Data;
import java.util.List;
@Data//lombok实现简化 get、set、tostring方法
public class Menu {
    // 菜单id
    private String  id;
    //菜单名称
    private String name;
    // 父菜单id
    private String pid;
    // 子菜单
    private List<Menu> menuChildren;
}

Copy after login

xml file

<?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.qcby.mapper.MenuMapper">
    <select id="selectByPid" resultType="com.qcby.entity.Menu">
        SELECT * FROM menu WHERE  pid=#{pid}
    </select>
    <select id="selectAll" resultType="com.qcby.entity.Menu">
        SELECT * FROM menu
    </select>
    <select id="selectAllNotBase" resultType="com.qcby.entity.Menu">
        SELECT * FROM menu where pid!= 0
    </select>
</mapper>

Copy after login

Mapper layer

package com.qcby.mapper;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.qcby.entity.Menu;
import org.apache.ibatis.annotations.Mapper;
import java.util.List;
@Mapper
public interface MenuMapper extends BaseMapper<Menu> {
    List<Menu> selectByPid(Integer pid);
    List<Menu> selectAll();
    List<Menu> selectAllNotBase();
}

Copy after login

service layer

package com.qcby.service;
import com.baomidou.mybatisplus.extension.service.IService;
import com.qcby.entity.Menu;
import java.util.List;
public interface MenuService extends IService<Menu> {
    List<Menu> selectByPid(Integer pid);
    List<Menu> selectAll();
    List<Menu> selectAllNotBase();
}

Copy after login

serviceImpl

package com.qcby.service.Impl;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.qcby.entity.Menu;
import com.qcby.mapper.MenuMapper;
import com.qcby.service.MenuService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.List;
@Service
public class MenuServiceImpl extends ServiceImpl<MenuMapper, Menu> implements MenuService {
    @Autowired
    private MenuMapper menuMapper;
    @Override
    public List<Menu> selectByPid(Integer pid) {
        return menuMapper.selectByPid(pid);
    }
    @Override
    public List<Menu> selectAll() {
        return menuMapper.selectAll();
    }
    @Override
    public List<Menu> selectAllNotBase() {
        return menuMapper.selectAllNotBase();
    }
}

Copy after login

controller layer

package com.qcby.controller;
import com.baomidou.mybatisplus.core.toolkit.StringUtils;
import com.qcby.entity.Menu;
import com.qcby.mapper.MenuMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import java.util.ArrayList;
import java.util.List;
@RestController
@RequestMapping("menu")
public class MenuController {
    @Autowired
    private MenuMapper menuMapper;
    @RequestMapping("/getMenuTree")
    public List<Menu> getMenuTree(){
        List<Menu> menusBase = menuMapper.selectByPid(0);
        List<Menu> menuLNotBase = menuMapper.selectAllNotBase();
        for (Menu menu : menusBase) {
            List<Menu> menus = iterateMenus(menuLNotBase, menu.getId());
            menu.setMenuChildren(menus);
        }
        return  menusBase;
    }
    /**
     *多级菜单查询方法
     * @param menuVoList 不包含最高层次菜单的菜单集合
     * @param pid 父类id
     * @return
     */
    public List<Menu> iterateMenus(List<Menu> menuVoList,String pid){
        List<Menu> result = new ArrayList<Menu>();
        for (Menu menu : menuVoList) {
            //获取菜单的id
            String menuid = menu.getId();
            //获取菜单的父id
            String parentid = menu.getPid();
            if(StringUtils.isNotBlank(parentid)){
                if(parentid.equals(pid)){
                    //递归查询当前子菜单的子菜单
                    List<Menu> iterateMenu = iterateMenus(menuVoList,menuid);
                    menu.setMenuChildren(iterateMenu);
                    result.add(menu);
                }
            }
        }
        return result;
    }
}

Copy after login

Result display

How to implement menu tree recursively in Java

The above is the detailed content of How to implement menu tree recursively in Java. For more information, please follow other related articles on the PHP Chinese website!