mybatis_plus快速入门

尽量不要同时导入mybatis和mybatis_plus

1:新建数据库：

其对应的数据库 Schema 脚本如下：

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)
);

其对应的数据库 Data 脚本如下：

DELETE FROM user;

INSERT INTO user (id, name, age, email) VALUES
(1, 'Jone', 18, 'test1@baomidou.com'),
(2, 'Jack', 20, 'test2@baomidou.com'),
(3, 'Tom', 28, 'test3@baomidou.com'),
(4, 'Sandy', 21, 'test4@baomidou.com'),
(5, 'Billie', 24, 'test5@baomidou.com');

2：导入依赖：

引入 Spring Boot Starter 父工程：

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.2.5.RESEASE</version>
    <relativePath/>
</parent>

导入依赖

<dependency>
   <groupId>mysql</groupId>
   <artifactId>mysql-connector-java</artifactId>
   <version>8.0.25</version>
</dependency>
<dependency>
   <groupId>org.projectlombok</groupId>
   <artifactId>lombok</artifactId>
   <version>1.18.22</version>
</dependency>
<dependency>
   <groupId>com.baomidou</groupId>
   <artifactId>mybatis-plus-boot-starter</artifactId>
   <version>3.5.1</version>
</dependency>

<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>

配置application.yml

# DataSource Config
spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/mybatis?characterEncoding=utf-8&serverTimezone=GMT%2B8
    username: root
    password: 123456

编写实体类

@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
    private long id;
    private String name;
    private Integer age;
    private String email;

}

编写mapper接口

编写 Mapper 包下的 UserMapper接口

public interface UserMapper extends BaseMapper<User> {

}

在 Spring Boot 启动类中添加 @MapperScan 注解，扫描 Mapper 文件夹：

@MapperScan("mapper")//mapper为mapper文件夹的位置

添加测试类，进行功能测试

点开test里的测试类

@Autowired(required = false)
private UserMapper userMapper;

@Test
void contextLoads() {
   List<User> users = userMapper.selectList(null);
   users.forEach(System.out::println);
}