8.注解开发

对于简单的数据库操作可以使用注解开发，对于复杂的数据库操作不推荐使用！！

mybatis 的常用注解:

@Insert:新增

@Update:更新

@Delete:删除

@Select:查询

@Result:实现结果集封装

@ResultMap:实现引用

@Results 定义的封装

@One:实现一对一结果集封装

@Many:实现一对多结果集封装

@SelectProvider: 实现动态 SQL 映射

@CacheNamespace:实现注解二级缓存的使用 

 

注解开发的基本流程：

1.编写Mapper接口

2.在核心配置文件中注册Mapper接口

3.测试

 

注解的CRUD:

UserMapper

public interface UserMapper {

    @Select("select * from user")
    List<User> getUsers();

    @Select("select * from mybatis.user where id=#{id}")
    User getUserById(@Param("id") int id);

    @Insert("insert into mybatis.user values (#{id},#{name},#{password})")
    int addUser(User user);

    @Delete("delete from user where id=#{id}")
    int delUser(@Param("id") int id);

    @Update("update user set name=#{name} where id=#{id}")
    int updateUser(@Param("id") int id,@Param("name") String name);

}

mybatis-conifg.xml

<!--绑定接口-->
<mappers>
    <mapper class="com.zuo.dao.UserMapper"/>
</mappers>

UserDaoTest.java

public class UserDaoTest {
    @Test
    public void getUserList(){
        SqlSession sqlSession = MyBatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        List<User> userList = mapper.getUsers();
        for(User user:userList){
            System.out.println(user);
        }
        sqlSession.close();
    }

    @Test
    public void getUserById(){
        SqlSession sqlSession = MyBatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        User user = mapper.getUserById(1);
        System.out.println(user);
        sqlSession.close();
    }

    @Test
    public void addUser(){
        SqlSession sqlSession = MyBatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        mapper.addUser(new User(4,"mmmm","12346"));
        sqlSession.commit();
        sqlSession.close();
    }

    @Test
    public void delUser(){
        SqlSession sqlSession = MyBatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        mapper.delUser(0);
        sqlSession.commit();
        sqlSession.close();
    }

    @Test
    public void updateUser(){
        SqlSession sqlSession = MyBatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        mapper.updateUser(4,"zuozuozuo");
        sqlSession.close();
    }

}