Mybatis注解总结

Mybatis注解

第一步：建工程，导入坐标
第二步：实体类、接口

第三步：核心配置文件

SqlMapConfig.xml

  <mappers>
  		<!-- <mapper class="cn.flyingd.dao.IUserDao" /> -->
  		<package name="cn.flyingd.dao"></package>
  	</mappers>

第四步：完善接口上的注解

  public interface IUserDao {
      @Select(value="select * from user")
      List<User> findAll();
		
      @Select("select * from user where id= #{id}")
      User findById(Integer id);
		
      @Insert("insert into user(username,sex,birthday,address) values(#{userName},#{userSex},#{userBirthday},#{userAddress})")
      void insert(User user);
	
      @Update("update user set username = #{userName},sex=#{userSex},birthday= #{userBirthday},address=#{userAddress} where id=#{id}")
      void update(User user);
		
      @Delete("delete from user where id=#{id}")
      void deleteById(Integer id);
  }

第五步：测试

测试类的方法

  public class MybatisTest {
  public static void main(String[] args) {
  		//1.读取配置文件
  		InputStream in = Resources.getResourceAsStream("SqlMapConfig.xml");
  		//2.解析核心配置文件（解析注解），创建SqlSessionFactory对象
  		SqlSessionFactoryBuilder  builder = new SqlSessionFactoryBuilder();
  		SqlSessionFactory sqlSessionFactory = builder.build(in);
  		//3.创建SqlSession对象
  		SqlSession sqlSession = sqlSessionFactory.openSession();
  		//4.创建代理对象
  		IUserDao userDao = sqlSession.getMapper(IUserDao.class);
  		//5.调用方法
  		List<User> userList = userDao.findAll();
  		userDao.insert(user);
  		sqlSession.commit();
  		//6.释放资源
  		sqlSession.close();
  		in.close();
  	}
}

多对一，一对一

  public interface IAccountDao{
		
      @Select("select * from account")
      @Results(
          id="accountMap",
          value={
              @Result(id=true,column="id",property="id"),
              @Result(column="uid",property="uid"),
              @Result(column="money",property="money"),
              @Reulst(property="user",column="uid",
                  one=@One(select="cn.flyingd.dao.IUserDao.findById",fetchType= FetchType.LAZY))
          }
      )
      List<Account> findAll();
		
      @Select("select * from account where uid= #{uid}")
      List<Account> findAccountByUid(Integer uid);
  }

一对多,多对多

  public interface IUserDao {
      @Select(value="select * from user")
      @Results(
          id="userMap",
          value={
              @Result(id=true,column="id",property="id"),
              @Result(column="address",property="address"),
              @Result(column="username",property="username"),
              @Result(property="accountList",column="id",
                   many = @Many(select = "cn.flyingd.dao.IAccountDao.findAccountByUid",fetchType = FetchType.LAZY))
          }
      )
      List<User> findAll();
		
      @Select("select * from user where id= #{id}")
      User findById(Integer id);
  }

Mybatis注解

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