MyBatis-Plus学习笔记(一) 快速开始

学习官方文档（https://mp.baomidou.com/guide/quick-start.html#%E5%BC%80%E5%A7%8B%E4%BD%BF%E7%94%A8笔记

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一、创建数据库：mybatis_plus，添加表：User，插入数据

DROP TABLE IF EXISTS USER;
CREATE TABLE USER
(
	id BIGINT(20) NOT NULL COMMENT '主键ID',
	NAME VARCHAR(30) NULL DEFAULT NULL COMMENT '姓名',
	age INT(11) NULL DEFAULT NULL COMMENT '年龄',
	email VARCHAR(50) NULL DEFAULT NULL COMMENT '邮箱',
	PRIMARY KEY (id)
);

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

二、新建SpringBoot工程并删除没用的文件

三、添加依赖

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
</dependency>

<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>mybatis-plus-boot-starter</artifactId>
    <version>3.0.5</version>
</dependency>

<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
</dependency>

四、编写application.yml，配置数据库连接

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/mybatis_plus?useUnicode=true&characterEncoding=UTF-8&useSSL=true&serverTimezone=GMT%2B8
    username: root
    password: 123456

• 8版本的驱动可以驱动5版本的mysql
• 用8版本的驱动时要有时区配置，如：serverTimezone=GMT%2B8，否则会报错

五、写实体类

@Data
@NoArgsConstructor
@AllArgsConstructor
public class User {

    private Long id;
    private String name;
    private Integer age;
    private String email;
}

六、编写Mapper类

@Repository
public interface UserMapper extends BaseMapper<User> {

}

继承BaseMapper<>即可实现User表的CRUD功能

七、在SpringBoot启动类中添加@MapperScan注解

          配置 mapper 扫描路径

@MapperScan("com.zhou.mapper")
@SpringBootApplication
public class MybatisPlusApplication {

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

}

八、添加测试类，进行功能测试

@SpringBootTest
class MybatisPlusApplicationTests {

    @Autowired
    private UserMapper userMapper;

    @Test
    void contextLoads() {

        List<User> users = userMapper.selectList(null);
        users.forEach(System.out::println);
    }

}

UserMapper 中的 selectList() 方法的参数为 MP 内置的条件封装器 Wrapper，无任何条件写null即可

九、编写application.yml配置日志

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

十、查看测试日志结果