select
      orders.*,
      t_user.id user_id,
      t_user.address,
      t_user.name,
      t_user.brithday,
      orderdetail.id orderdetail_id,
      orderdetail.orderid,
      orderdetail.itemsid,
      items.id items_id,
      items.name items_name,
      items.price items_price
      from
      orders,
      t_user,
      orderdetail,
      items
      where
      orders.userid=t_user.id AND orderdetail.orderid=orders.id AND orderdetail.itemsId = items.id

public class User {
  private int id;
  private String name;
  private String pwd;
  private String address;
  private Date brithday;
  private List<Orders> ordersList;//看这里 用户创建的订单列表
}

public class Orders {
  private int id;
  private String note;
  private Date dateTime;
  private String number;
  private int userId;
  private User user;
  private List<OrdersDetail> ordersDetails;//一个订单包括多个订单明细

public class OrdersDetail {
  private int id;
  private int orderId;
  private int itemsId;
  private Items items;//一条订单明细包括一条商品信息  

<!--查询用户所购买的商品信息resultMap-->
  <resultMap id="UserAndItemsResultMap" type="com.djp.pojo.User">
    <!--配置用户信息-->
    <id column="user_id" property="id"/>
    <result column="address" property="address"/>
    <result column="name" property="name"/>
    <result column="brithday" property="brithday"/>
    <!--配置用户创建的订单信息，一个用户创建了多个订单-->
    <collection property="ordersList" ofType="com.djp.pojo.Orders">
      <id column="id" property="id"/>
      <result column="note" property="note"/>
      <result column="dateTime" property="dateTime"/>
      <result column="userId" property="userId"/>
      <result column="number" property="number"/>
      <!--配置订单明细信息 一个订单包含多个订单明细-->
      <collection property="ordersDetails" ofType="com.djp.pojo.OrdersDetail">
        <id column="orderdetail_id" property="id"/>
        <result column="orderId" property="orderId"/>
        <result column="itemsid" property="itemsId"/>
        <!--配置商品信息 一个明细包括一个商品-->
        <association property="items" javaType="com.djp.pojo.Items">
          <id column="items_id" property="id"/>
          <result column="items_name" property="name"/>
          <result column="items_price" property="price"/>
        </association>
      </collection>
    </collection>
  </resultMap>
  <!--查询用户所购买的商品信息-->
  <select id="findUserAndItemsResultMap" resultMap="UserAndItemsResultMap">
    select
      orders.*,
      t_user.id user_id,
      t_user.address,
      t_user.name,
      t_user.brithday,
      orderdetail.id orderdetail_id,
      orderdetail.orderid,
      orderdetail.itemsid,
      items.id items_id,
      items.name items_name,
      items.price items_price
      from
      orders,
      t_user,
      orderdetail,
      items
      where
      orders.userid=t_user.id AND orderdetail.orderid=orders.id AND orderdetail.itemsId = items.id
  </select>

public interface OrdersCustomMapper {
  /**
   * 查询用户所购买的商品
   * @return
   * @throws Exception
   */
  List<User> findUserAndItemsResultMap() throws Exception;

/**findUserAndItemsResultMap
   * 查询用户所购买的商品信息
   */
  @Test
  public void testfindUserAndItemsResultMap() {
    try {
      System.out.println("start.................");
      //通过得到的SqlSessionFactory打开回话sqlSession
      SqlSession sqlSession = SqlSessionFactory.openSession();
      //通过会话得到用户的代理
      OrdersCustomMapper ordersCustomMapper = sqlSession.getMapper(OrdersCustomMapper.class);
      List<User> list = ordersCustomMapper.findUserAndItemsResultMap();
      System.out.println("end.................");
    } catch (Exception e) {
      e.printStackTrace();
    }
  }