[MyBatisPlus]入门案例

Posted 2022-03-16 唐火

入门案例

创建测试数据库和表

CREATE DATABASE `mybatis_plus` /*!40100 DEFAULT CHARACTER SET utf8mb4 */; use `mybatis_plus`;
 CREATE TABLE `user` 
 ( `id` bigint(20) NOT NULL COMMENT '主键ID',
  `name` varchar(30) DEFAULT NULL COMMENT '姓名', `age` int(11) DEFAULT NULL COMMENT '年龄', 
  `email` varchar(50) DEFAULT NULL COMMENT '邮箱', 
  PRIMARY KEY (`id`) )
   ENGINE=InnoDB DEFAULT CHARSET=utf8;

INSERT INTO user (id, name, age, email) VALUES 
(1, 'Jone', 18, '[e-mail]'), 
(2, 'Jack', 20, '[e-mail]'), 
(3, 'Tom', 28, '[e-mail]'),
 (4, 'Sandy', 21, '[e-mail]'), 
 (5, 'Billie', 24, '[e-mail]');

创建SpringBoot工程

引入依赖

<!--        mybatis plus 启动器-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.5.1</version>
        </dependency>

<!--        lombok用于简化实体类开发-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>


<!--        mysql驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>

idea中安装lombok插件

配置application.yml

spring:
  # 配置数据源信息
  datasource:
    # 配置数据源类型
    type: com.zaxxer.hikari.HikariDataSource
    # 配置连接数据库的各个信息
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/mybatis_plus?serverTimezone=UTC&&characterEncoding=utf- 8&useSSL=false
    username: root
    password: password

创建实体类

package com.xxxx.mybatisplus.pojo;


import lombok.*;

//@NoArgsConstructor
//@AllArgsConstructor
//@Getter
//@Setter
//@EqualsAndHashCode
@Data
public class User 

    // mybatis plus默认用雪花算法, id 会比较长
    private Long id;

    private String name;

    private Integer age;

    private String email;

添加mapper

package com.xxxx.mybatisplus.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.xxxx.mybatisplus.pojo.User;


// 将类或者接口标记为持久层组件 这样就不会看见test类中的红线警告了 
@Repository
public interface UserMapper extends BaseMapper<User> 

在启动类上添加注解扫描mapper

package com.xxxx.mybatisplus;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication

// 扫描mapper接口所在的包
@MapperScan("com.xxxx.mybatisplus.mapper")
public class MybatisplusApplication 

    public static void main(String[] args) 
        SpringApplication.run(MybatisplusApplication.class, args);
    

测试

package com.xxxx.mybatisplus;

import com.xxxx.mybatisplus.mapper.UserMapper;
import com.xxxx.mybatisplus.pojo.User;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import java.util.List;

@SpringBootTest
public class MyBatisPlusTest 

    @Autowired
    private UserMapper userMapper;


    @Test
    public void testSelectList()
    
        // 通过条件构造器查询一个list集合,若没有条件,则可以设置null为参数
        List<User> list = userMapper.selectList(null);
        list.forEach(System.out::println);
    

加入日志功能

加入配置

mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl