MybatisPlus的简单使用

引入依赖

一个简单的springboot项目

<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <optional>true</optional>
</dependency>
<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>mybatis-plus-boot-starter</artifactId>
    <version>3.4.0</version>
</dependency>
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.48</version>
</dependency>

配置文件

spring:
  application:
    name: mybatisplus-demo
  datasource:
    url: jdbc:mysql://localhost:3306/mybatis_plus?useUnicode=true&serverTimezone=GMT%2B8&characterEncoding=UTF-8&useSSL=false
    username: root
    password: 91597489
    driverClassName: com.mysql.jdbc.Driver
logging:
  level:
    com.atguigu.mybatisplus.demo: debug
mybatis-plus:
  global-config:
    db-config:
      id-type: auto  #数据库id自增

数据库

使用mysql数据库

# 创建表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)
);

# 添加数据
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]');

编码

实体类User

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

编写mapper类，UserMapper

public interface UserMapper extends BaseMapper<User> {

}

分页配置

@Configuration
public class MybatisPlusConfig {
    @Bean
    public PaginationInterceptor paginationInterceptor() {
        PaginationInterceptor paginationInterceptor = new PaginationInterceptor();
        return paginationInterceptor;
    }
}

测试

@Resource
private UserMapper userMapper;

@Test
void contextLoads() {
    //User user = userMapper.selectById(1L);
    //System.out.println(user);
    //List<User> users = userMapper.selectBatchIds(Arrays.asList(1, 2, 4));
    //users.stream().forEach(user1 -> System.out.println(user1));

    QueryWrapper<User> wrapper = new QueryWrapper<>();
    //wrapper.like("name","J");
    wrapper.gt("age", 18);
    wrapper.orderByDesc("age");
    wrapper.select("id", "name", "age");
    //List<User> users = userMapper.selectList(wrapper);
    //users.stream().forEach(user1 -> System.out.println(user1));

    IPage<User> page = userMapper.selectPage(new Page<>(2, 3), wrapper);
    page.getRecords().forEach(System.out::println);
}

@Test
void insertTest() {
    userMapper.insert(new User(null, "wangjie", 23, "[email protected]"));
}

更具id更新：

@Test
void updateTest() {
    //会判断传入值是否为null
    userMapper.updateById(new User(7L, "隔壁老王", 30, null));
}

控制台sql日志

==> Preparing: UPDATE user SET name=?, age=? WHERE id=?
==> Parameters: 隔壁老王(String), 30(Integer), 7(Long)
<==  Updates: 1

根据其他条件更新：

@Test
void updateTest() {
    userMapper.update(new User(null, "隔壁老徐", 40, null),
                      new UpdateWrapper<>(new User(null, null, null, "[email protected]")));
}

控制台sql日志

==> Preparing: UPDATE user SET name=?, age=? WHERE email=?
==> Parameters: 隔壁老徐(String), 40(Integer), [email protected](String)
<==  Updates: 1

删除：

@Test
void delTest(){
    userMapper.deleteById(7L);
}