创建user
表
现有一张 User
表,其表结构如下:
id | name | age | |
---|---|---|---|
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] |
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, '[email protected]'),
(2, 'Jack', 20, '[email protected]'),
(3, 'Tom', 28, '[email protected]'),
(4, 'Sandy', 21, '[email protected]'),
(5, 'Billie', 24, '[email protected]');
创建工程引入依赖
引入 spring-boot-starter
、spring-boot-starter-test
、mybatis-plus-boot-starter
依赖:
<!-- 数据库驱动 -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>
<!-- lombok -->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
</dependency>
<!-- mybatis-plus -->
<dependency>
<groupId>com.baomidou</groupId>
<artifactId>mybatis-plus-boot-starter</artifactId>
<version>3.0.5</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
配置
在 application.yml
配置文件中添加MySql数据库的相关配置:
spring:
datasource:
#MySQL配置
driverClassName: com.mysql.cj.jdbc.Driver
url: jdbc:mysql://localhost:3306/mybatis_plus?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=GMT&allowPublicKeyRetrieval=true
username: root
password: 123456
在 Spring Boot 启动类中添加 @MapperScan
注解,扫描 Mapper 文件夹:
@MapperScan("com.jiuqi.mapper")
@SpringBootApplication
public class MybatisPlusApplication {
public static void main(String[] args) {
SpringApplication.run(MybatisPlusApplication.class, args);
}
}
编码
编写实体类 User.java
@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
private Long id;
private String name;
private Integer age;
private String email;
}
编写Mapper类 UserMapper.java
@Repository
public interface UserMapper extends BaseMapper<User> {
}
开始使用
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
,所以不填写就是无任何条件
控制台输出: