MyBatis映射文件深入

测试代码ifforeachSQL语句片段抽取

public class MapperTest {
    @Test
    public void test1() throws IOException {
        InputStream resourceAsStream = Resources.getResourceAsStream("SqlMapConfig.xml");
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
        SqlSession sqlSession = sqlSessionFactory.openSession();

        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
// if测试
        //模拟user
        User condition = new User();
        condition.setId(1);
        condition.setUsername("zhangsan");
        condition.setPassword("123");
        List user = mapper.findByConditon(condition);
        System.out.println(user);
        
// foreach测试
		//模拟Ids的数据
        List ids = new ArrayList();
        ids.add(1);
        ids.add(2);
        ids.add(3);
        List userList = mapper.findByIds(ids);
        System.out.println(userList);
    }
}

UserMapper.xml配置文件里面的数据库查询拼接语句如果where里面没有为真的语句则where也不会创建

    
        select * from user 
        
            
                and id=#{id}
            
            
                and username=#{username}
            
            
                and password=#{password}
            
        
    

open表示开始的位置close表示结束item表示遍历的元素赋值给谁separator表示分隔符

    select * from user
    
        
            #{id}
        
    

 
SQL语句片段抽取 

    select * from user
    
    
        
        
            
                and id=#{id}
            
            
                and username=#{username}
            
            
                and password=#{password}