基础使用

• 配置日志输出

# application.yml中配置如下
mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

• 基本crud操作

@SpringBootTest
public class MyBatisPlusTest {

    @Autowired
    private UserMapper userMapper;

    /** 
     * 新增的id由mybatis plus使用雪花算法生成
     * 新增时没有指定id
     */
    @Test
    public void testInsert(){
        //实现新增用户信息
        //INSERT INTO user ( id, name, age, email ) VALUES ( ?, ?, ?, ? )
        User user = new User();
        user.setName("张三");
        user.setAge(23);
        user.setEmail("zhangsan@atguigu.com");
        int result = userMapper.insert(user);
        System.out.println("result:"+result);
        System.out.println("id:"+user.getId());
    }

    @Test
    public void testDelete(){
        //通过id删除用户信息
        //DELETE FROM user WHERE id=?
        /*int result = userMapper.deleteById(1492767055210991617L);
        System.out.println("result:"+result);*/
        //根据map集合中所设置的条件删除用户信息
        //DELETE FROM user WHERE name = ? AND age = ?
        /*Map<String, Object> map = new HashMap<>();
        map.put("name", "张三");
        map.put("age", 23);
        int result = userMapper.deleteByMap(map);
        System.out.println("result:"+result);*/
        //通过多个id实现批量删除
        //DELETE FROM user WHERE id IN ( ? , ? , ? )
        List<Long> list = Arrays.asList(1L, 2L, 3L);
        int result = userMapper.deleteBatchIds(list);
        System.out.println("result:"+result);
    }

    @Test
    public void testUpdate(){
        //修改用户信息
        //UPDATE user SET name=?, email=? WHERE id=?
        User user = new User();
        user.setId(4L);
        user.setName("李四");
        user.setEmail("lisi@atguigu.com");
        int result = userMapper.updateById(user);
        System.out.println("result:"+result);
    }

    @Test
    public void testSelect(){
        //通过id查询用户信息
        //SELECT id,name,age,email FROM user WHERE id=?
        /*User user = userMapper.selectById(1L);
        System.out.println(user);*/
        //根据多个id查询多个用户信息
        //SELECT id,name,age,email FROM user WHERE id IN ( ? , ? , ? )
        /*List<Long> list = Arrays.asList(1L, 2L, 3L);
        List<User> users = userMapper.selectBatchIds(list);
        users.forEach(System.out::println);*/
        //根据map集合中的条件查询用户信息
        //SELECT id,name,age,email FROM user WHERE name = ? AND age = ?
        /*Map<String, Object> map = new HashMap<>();
        map.put("name", "Jack");
        map.put("age", 20);
        List<User> users = userMapper.selectByMap(map);
        users.forEach(System.out::println);*/
        //查询所有数据
        //SELECT id,name,age,email FROM user
        List<User> users = userMapper.selectList(null);
        users.forEach(System.out::println);
    }

}

• 自定义sql

# mybatis plus默认的配置为如下
# 当不写如下配置时，如果要写映射文件，则必须将映射文件放在mapper目录下
# 如果想放在其他的目录，则需指定
mybatis-plus:
  mapper-locations: classpath:mapper/*.xml    # 扫描映射文件

• 编写mapper

@Repository
public interface UserMapper extends BaseMapper<User> {

    /**
     * 根据id查询用户信息为map集合
     * @param id
     * @return
     */
    Map<String, Object> selectMapById(Long id);

}

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.atguigu.mybatisplus.mapper.UserMapper">

    <!--Map<String, Object> selectMapById(Long id);-->
    <select id="selectMapById" resultType="map">
        select id,name,age,email from user where id = #{id}
    </select>

</mapper>

• 测试

@Test
public void testSelect(){
    Map<String, Object> map = userMapper.selectMapById(1L);
    System.out.println(map);
}

• 创建Service接口和实现类

public interface UserService extends IService<User> {
}

@Service
public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements UserService {
}

• 测试

@SpringBootTest
public class MyBatisPlusServiceTest {

    @Autowired
    private UserService userService;

    @Test
    public void testGetCount(){
        //查询总记录数
        //SELECT COUNT( * ) FROM user
        long count = userService.count();
        System.out.println("总记录数："+count);
    }

    @Test
    public void testInsertMore(){
        // 批量添加操作
        // 没有指定id
        //INSERT INTO user ( id, name, age ) VALUES ( ?, ?, ? )
        List<User> list = new ArrayList<>();
        for (int i = 1; i <= 10; i++) {
            User user = new User();
            user.setName("ybc"+i);
            user.setAge(20+i);
            list.add(user);
        }
        boolean b = userService.saveBatch(list);
        System.out.println(b);
    }

}