Mybatis：注解完成增删改查

使用注解来映射简单语句会使得代码显得更加简洁，但是对于稍微复杂一些的语句，注解不仅力不从心，还会使本就复杂的sql语句混乱不堪，因此，如果需要做一些很复杂的操作，最好用xml来映射语句

    @Select("select * from tb_user where id = #{id}")User selectByUserId(int id);

@Testpublic void testSelectbyId() throws Exception{// 加载mybatis的核心配置文件，获取SqlSessionFactoryString resource = "mybatis-config.xml";InputStream inputStream = Resources.getResourceAsStream(resource);SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);// 获取SqlSession对象，用它来执行sqlSqlSession sqlSession = sqlSessionFactory.openSession();// 获取UserMapper接口的代理对象UserMapper userMapper = sqlSession.getMapper(UserMapper.class);int id = 3;User user = userMapper.selectByUserId(id);System.out.println(user);sqlSession.close();}