Mybatis Plus 通用枚举的使用

日常开发中经常会用到枚举类型，在 Mybatis Plus 中使用枚举，可以提高代码的可读性，省去数据类型的转换，非常方便。

首先把依赖的包添加进去：

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <scope>test</scope>
</dependency>
<!-- lombok -->
<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
</dependency>
<!-- hutool -->
<dependency>
    <groupId>cn.hutool</groupId>
    <artifactId>hutool-all</artifactId>
    <version>5.2.5</version>
</dependency>
<!-- mybatis plus -->
<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>mybatis-plus-boot-starter</artifactId>
    <version>3.0.5</version>
</dependency>
<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>mybatis-plus-extension</artifactId>
    <version>3.4.0</version>
</dependency>
<!-- druid -->
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid-spring-boot-starter</artifactId>
    <version>1.1.21</version>
    <scope>compile</scope>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!-- mysql -->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <scope>runtime</scope>
</dependency>
<dependency>
    <groupId>org.springframework.data</groupId>
    <artifactId>spring-data-commons</artifactId>
    <version>2.2.4.RELEASE</version>
</dependency>

之后按照步骤一步一步配置：

1.定义枚举类型

package com.example.demo.enums;

import com.baomidou.mybatisplus.annotation.IEnum;
import lombok.Getter;

@Getter
public enum GenderTypeEnum implements IEnum<Integer> {

    /**
     * 女
     */
    WOMAN(0, "女"),

    /**
     * 男
     */
    MAN(1, "男"),

    /**
     * 保密
     */
    PRIVACY(2, "保密");

    private Integer value;

    private String message;

    GenderTypeEnum(Integer value, String message) {
        this.value = value;
        this.message = message;
    }

    @Override
    public Integer getValue() {
        return this.value;
    }

    @Override
    public String toString() {
        return this.message;
    }
}

2.配置枚举包扫描

有两种方式进行配置：

(1) 在配置文件中新增配置项

mybatis-plus.type-enums-package=com.example.demo.enums

(2) 在Java 配置类中添加配置项

	@Bean("sqlSessionFactory")
    public SqlSessionFactory sqlSessionFactory() throws Exception {
        MybatisSqlSessionFactoryBean sqlSessionFactory = new MybatisSqlSessionFactoryBean();
        ......
        sqlSessionFactory.setTypeEnumsPackage("com.example.demo.enums");
        return sqlSessionFactory.getObject();
    }

这里的路径: com.example.demo.enums 配置的是枚举类所在包名。

3.创建数据库表

CREATE TABLE `user` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) DEFAULT NULL,
  `sex` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

4.创建使用枚举的实体类

package com.example.demo.entity;

import com.baomidou.mybatisplus.annotations.TableId;
import com.baomidou.mybatisplus.annotations.TableName;
import com.baomidou.mybatisplus.enums.IdType;
import com.example.demo.enums.GenderTypeEnum;
import lombok.Data;
import org.springframework.data.annotation.Id;

/**
 * @author: jichunyang
 * @description: 用户实体类
 * @date: 2021/3/18 10:34
 **/
@Data
@TableName("user")
public class User {
    /**
     * 主键
     */
    @Id
    @TableId(type = IdType.AUTO)
    private Long id;

    /**
     * 名字
     */
    private String name;

    /**
     * 性别(定义为枚举类型)
     */
    private GenderTypeEnum sex = GenderTypeEnum.PRIVACY;
}

这里的性别被定义为枚举类型，实际库表中存储的是整型，数据内容如下所示：

5.创建查询使用的服务类

package com.example.demo.service;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.example.demo.entity.User;
import com.example.demo.enums.GenderTypeEnum;
import com.example.demo.entity.mapper.UserMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * @author: jichunyang
 * @description: 服务类
 * @date: 2021/3/18 14:52
 **/
@Service
public class EnumService {

    @Autowired
    private UserMapper userMapper;

    public Map getAllUsers() {
        QueryWrapper<User> queryWrapper = new QueryWrapper<>();
        // 只查询性别为“女”的用户
        queryWrapper.eq("sex", GenderTypeEnum.WOMAN);
        List<User> users = userMapper.selectList(queryWrapper);
        Map<String, List> map = new HashMap<>();
        map.put("info", users);
        return map;
    }
}

6.创建查询使用的控制类

package com.example.demo.controller;

import com.example.demo.service.EnumService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.Map;

/**
 * @author: jichunyang
 * @description:
 * @date: 2021/3/18 10:24
 **/
@RestController
public class EnumController {

    @Autowired
    private EnumService enumService;

    @GetMapping("/getAllUsers")
    public Map getAllUsers() {
        return enumService.getAllUsers();
    }
}

启动后，访问路径即可获取到对应数据：