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1、通过项目逐步深入了解Mybatis<一>

2、 通过项目逐步深入了解Mybatis<二>

本项目所有代码及文档都托管在 Github地址：https://github.com/zhisheng17/mybatis

Mybatis 高级知识

安排：对订单商品数据模型进行分析

订单商品数据模型

• Mapper 文件

OrdersMapperCustom.java

public interface OrdersMapperCustom
{
    public OrdersCustom findOrdersUser() throws Exception;
}

• 测试代码（记得在 SqlConfig.xml中添加载 OrdersMapperCustom.xml 文件）

   @Test
  public void testFindOrdersUser() throws Exception
  {
    SqlSession sqlSession = sqlSessionFactory.openSession();
    //创建OrdersMapperCustom对象,mybatis自动生成代理对象
    OrdersMapperCustom ordersMapperCustom = sqlSession.getMapper(OrdersMapperCustom.class);
    //调用OrdersMapperCustom的方法
     List<OrdersCustom> list = ordersMapperCustom.findOrdersUser();
    System.out.println(list);
    sqlSession.close();
  }

• 测试结果

<!--查询订单关联查询用户信息, 使用 resultMap-->
    <select id="findOrdersUserResultMap" resultMap="OrdersUserResultMap">
        SELECT orders.*, USER.username, USER.sex, USER.address FROM orders, USER WHERE orders.user_id = user.id
    </select>

• Mapper 文件

  public List<Orders> findOrdersUserResultMap() throws Exception;

• 测试代码

  @Test
   public void testFindOrdersUserResultMap() throws Exception
   {
       SqlSession sqlSession = sqlSessionFactory.openSession();
       //创建OrdersMapperCustom对象,mybatis自动生成代理对象
       OrdersMapperCustom ordersMapperCustom = sqlSession.getMapper(OrdersMapperCustom.class);
       //调用OrdersMapperCustom的方法
       List<Orders> list = ordersMapperCustom.findOrdersUserResultMap();
       System.out.println(list);
       sqlSession.close();
   }

• 测试结果

 <!--查询订单及订单明细信息, 使用 resultMap-->
    <select id="findOrdersAndOrderDetailResultMap" resultMap="OrdersAndOrderDetailResultMap">
        SELECT orders.*, USER.username, USER.sex, USER.address, orderdetail.id orderdetail_id, orderdetail.items_id, orderdetail.items_num, orderdetail.orders_id
        FROM orders, USER,orderdetail WHERE orders.user_id = user.id AND orderdetail.orders_id=orders.id
    </select>

Mapper 文件

public List<Orders> findOrdersAndOrderDetailResultMap() throws Exception;

测试文件

@Test
    public void testFindOrdersAndOrderDetailResultMap() throws Exception
    {
        SqlSession sqlSession = sqlSessionFactory.openSession();
        //创建OrdersMapperCustom对象,mybatis自动生成代理对象
        OrdersMapperCustom ordersMapperCustom = sqlSession.getMapper(OrdersMapperCustom.class);
        //调用OrdersMapperCustom的方法
        List<Orders> list = ordersMapperCustom.findOrdersAndOrderDetailResultMap();
        System.out.println(list);
        sqlSession.close();
    }

测试结果

映射文件

<!--查询用户及用户购买商品信息, 使用 resultMap-->
    <select id="findUserAndItemsResultMap" resultMap="UserAndItemsResultMap">
        SELECT orders.*, USER.username, USER.sex, USER.address, orderdetail.id orderdetail_id, orderdetail.items_id, orderdetail.items_num, orderdetail.orders_id
        FROM orders, USER,orderdetail WHERE orders.user_id = user.id AND orderdetail.orders_id=orders.id
    </select>

Mapper 文件

public List<User> findUserAndItemsResultMap() throws  Exception;

测试文件

@Test
    public void testFindUserAndItemsResultMap() throws Exception
    {
        SqlSession sqlSession = sqlSessionFactory.openSession();
        //创建OrdersMapperCustom对象,mybatis自动生成代理对象
        OrdersMapperCustom ordersMapperCustom = sqlSession.getMapper(OrdersMapperCustom.class);
        //调用OrdersMapperCustom的方法
        List<User> list = ordersMapperCustom.findUserAndItemsResultMap();
        System.out.println(list);
        sqlSession.close();
    }

测试：

    原文作者：zhisheng
    原文地址: https://segmentfault.com/a/1190000007691419
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