Mybatis之使用注解开发

使用注解开发

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//使用注解、
@Select ("select * from mybatis.saxon")
List<User> getUser();

这是我们的映射就要使用类名来注册

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<mappers>
  <mapper class="com.saxon.Dao.UserMapper"/>
</mappers>

测试

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

这个办法只可以处理简单的sql语句，处理复杂的sql语句，会使得程序变得混乱不堪；一些复杂的操作我们还是推荐使用我们的xml配置文件来完成；当然我们也可以把二者进行一个结合，但是我们注册的时候，我们的接口名和xml名字要一样；

二.CRUD

1.查询

//使用注解查询语句
   @Select ("select * from mybatis.saxon where id=#{id}")
   User select(int id);
   
 @Test
   public void Test(){
       SqlSession sqlSession = MybatisUnit.getSqlSession ();
       UserMapper mapper = sqlSession.getMapper (UserMapper.class);
       User select = mapper.select (1);
       System.out.println (select);
       sqlSession.close ();
   }

2.添加

//使用注解添加用户
   @Insert ("insert into mybatis.saxon(id,user,pwd) values(#{id},#{user},#{password})")
   void insert(User user);
   
   
public void test(){
       SqlSession sqlSession = MybatisUnit.getSqlSession ();
       UserMapper mapper = sqlSession.getMapper (UserMapper.class);
       mapper.insert (new User (2,"saxon","1234567"));
       sqlSession.commit ();
       sqlSession.close ();
   }

3.更新

@Update ("update mybatis.saxon set user=#{user} , pwd=#{pwd}  where id=#{id}")
void update (User user);


 @org.junit.Test
public void test(){
    SqlSession sqlSession = MybatisUnit.getSqlSession ();
    UserMapper mapper = sqlSession.getMapper (UserMapper.class);
    mapper.update (new User (2,"hello","12345 67"));
    sqlSession.commit ();
    sqlSession.close ();
}

4.删除

//使用注解删除用户
    @Delete ("delete from mybatis.saxon where id=#{id}")
    void delete(@Param ("id") int id);
   
   
   
   @org.junit.Test
    public void test(){
        SqlSession sqlSession = MybatisUnit.getSqlSession ();
        UserMapper mapper = sqlSession.getMapper (UserMapper.class);
        mapper.delete (2);
        sqlSession.commit ();
        sqlSession.close ();
    }