mybatis学习之高级映射中的一对多查询

一对多查询

mybatis使用resultMap的collection对关联查询的多条记录映射到一个list集合属性中

使用resultType实现：
将订单明细映射到order中的orderdetails中，需要自行处理（双重循环遍历），将订单明细存储在orderdetails的集合中。

在此处使用resultMap实现

1、需求

查询订单及订单明细的信息

2 、sql语句

确定主查询表：订单表 order
确定关联查询表： 订单明细表 orderdetail
在一对一查询的基础上，添加订单明细表的关联即可

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`

3、分析

若使用resultType将上面的查询结果集映射到pojo中时，订单信息的pojo中会重复 要求： 对于order映射不能出现重复记录 设想： 在order,java类中添加List<OrderDetail>属性  最终会将订单信息映射到order中，订单所对应的订单明细映射到order中的list中去 结果： 映射成的order记录数为两条（order信息不重复） 每一个order中的orderdetail属性存储了该订单所对应的订单明细 

4、在orders类中添加list订单明细属性

private Integer id;
private Integer userId;
private String number;
private Date  createtime;
private String note;
//用户信息
private User user;

//订单详情List
private List<OrderDetail> OrderDetails;

5、resultMap的定义

<!--
订单及订单明细的resultMap
使用继承extends，不用在此配置订单信息和用户信息的配置
-->
<resultMap id="OrdersAndOrderdetailResultMap" type="pojo.Order" extends="OrderUserResultMap">
<!-- 订单信息 -->
<!-- 用户信息 -->

<!--
订单明细信息
一个订单包含多条明细
要使用collection进行映射
collection:对关联的查询的多条记录映射到集合中去
property:将关联的多条记录映射到order中的哪条属性离去
ofType:指定要映射的集合属性中的pojo的类型,即orderdetail
-->
<collection property="orderDetails" ofType="pojo.OrderDetail">
<!-- 订单明细的唯一标识 -->
<id column="orderdetail_id" property="id" />
<result column="items_id" property="itemsId"/>
<result column="items_num" property="itemsNum" />
<result column="orders_id" property="ordersId" />
<result />
</collection>
</resultMap>

6、mapper.xml

    <!-- 查询订单 关联查询用户 及 订单明细  使用resultMap -->
<select id="findOrderAndOrderDetailResultMap" 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>

7、mapper.java

//查询订单关联查询用户和订单详情
public List<Order> findOrderAndOrderDetailResultMap() throws Exception;

8、测试代码

@Test
public void testFindOrderAndOrderDetailResultMap() throws Exception{
SqlSession sqlSession = sqlSessionFactory.openSession();
OrderMapperCustom orderMapperCustom = sqlSession.getMapper(OrderMapperCustom.class);
List<Order> list = orderMapperCustom.findOrderAndOrderDetailResultMap();
System.out.println(list);
}

9、log4j输出结果

DEBUG [main] - Logging initialized using 'class org.apache.ibatis.logging.slf4j.Slf4jImpl' adapter.
DEBUG [main] - Class not found: org.jboss.vfs.VFS
DEBUG [main] - JBoss 6 VFS API is not available in this environment.
DEBUG [main] - Class not found: org.jboss.vfs.VirtualFile
DEBUG [main] - VFS implementation org.apache.ibatis.io.JBoss6VFS is not valid in this environment.
DEBUG [main] - Using VFS adapter org.apache.ibatis.io.DefaultVFS
DEBUG [main] - Find JAR URL: file:/E:/%e5%a4%a7%e5%ad%a6%e9%a1%b9%e7%9b%ae/IDEA%20Project/mybatis/out/production/mybatis/pojo
DEBUG [main] - Not a JAR: file:/E:/%e5%a4%a7%e5%ad%a6%e9%a1%b9%e7%9b%ae/IDEA%20Project/mybatis/out/production/mybatis/pojo
DEBUG [main] - Reader entry: Items.class
DEBUG [main] - Reader entry: Order.class
DEBUG [main] - Reader entry: OrderCustom.class
DEBUG [main] - Reader entry: OrderDetail.class
DEBUG [main] - Reader entry: User.class
DEBUG [main] - Reader entry: UserCustom.class
DEBUG [main] - Reader entry: UserQueryVo.class
DEBUG [main] - Listing file:/E:/%e5%a4%a7%e5%ad%a6%e9%a1%b9%e7%9b%ae/IDEA%20Project/mybatis/out/production/mybatis/pojo
DEBUG [main] - Find JAR URL: file:/E:/%e5%a4%a7%e5%ad%a6%e9%a1%b9%e7%9b%ae/IDEA%20Project/mybatis/out/production/mybatis/pojo/Items.class
DEBUG [main] - Not a JAR: file:/E:/%e5%a4%a7%e5%ad%a6%e9%a1%b9%e7%9b%ae/IDEA%20Project/mybatis/out/production/mybatis/pojo/Items.class
DEBUG [main] - Reader entry: ����   4 X
DEBUG [main] - Find JAR URL: file:/E:/%e5%a4%a7%e5%ad%a6%e9%a1%b9%e7%9b%ae/IDEA%20Project/mybatis/out/production/mybatis/pojo/Order.class
DEBUG [main] - Not a JAR: file:/E:/%e5%a4%a7%e5%ad%a6%e9%a1%b9%e7%9b%ae/IDEA%20Project/mybatis/out/production/mybatis/pojo/Order.class
DEBUG [main] - Reader entry: ����   4 f
DEBUG [main] - Find JAR URL: file:/E:/%e5%a4%a7%e5%ad%a6%e9%a1%b9%e7%9b%ae/IDEA%20Project/mybatis/out/production/mybatis/pojo/OrderCustom.class
DEBUG [main] - Not a JAR: file:/E:/%e5%a4%a7%e5%ad%a6%e9%a1%b9%e7%9b%ae/IDEA%20Project/mybatis/out/production/mybatis/pojo/OrderCustom.class
DEBUG [main] - Reader entry: ����   4 "
DEBUG [main] - Find JAR URL: file:/E:/%e5%a4%a7%e5%ad%a6%e9%a1%b9%e7%9b%ae/IDEA%20Project/mybatis/out/production/mybatis/pojo/OrderDetail.class
DEBUG [main] - Not a JAR: file:/E:/%e5%a4%a7%e5%ad%a6%e9%a1%b9%e7%9b%ae/IDEA%20Project/mybatis/out/production/mybatis/pojo/OrderDetail.class
DEBUG [main] - Reader entry: ����   4 @
DEBUG [main] - Find JAR URL: file:/E:/%e5%a4%a7%e5%ad%a6%e9%a1%b9%e7%9b%ae/IDEA%20Project/mybatis/out/production/mybatis/pojo/User.class
DEBUG [main] - Not a JAR: file:/E:/%e5%a4%a7%e5%ad%a6%e9%a1%b9%e7%9b%ae/IDEA%20Project/mybatis/out/production/mybatis/pojo/User.class
DEBUG [main] - Reader entry: ����   4 L
DEBUG [main] - Find JAR URL: file:/E:/%e5%a4%a7%e5%ad%a6%e9%a1%b9%e7%9b%ae/IDEA%20Project/mybatis/out/production/mybatis/pojo/UserCustom.class
DEBUG [main] - Not a JAR: file:/E:/%e5%a4%a7%e5%ad%a6%e9%a1%b9%e7%9b%ae/IDEA%20Project/mybatis/out/production/mybatis/pojo/UserCustom.class
DEBUG [main] - Reader entry: ����   4
DEBUG [main] - Find JAR URL: file:/E:/%e5%a4%a7%e5%ad%a6%e9%a1%b9%e7%9b%ae/IDEA%20Project/mybatis/out/production/mybatis/pojo/UserQueryVo.class
DEBUG [main] - Not a JAR: file:/E:/%e5%a4%a7%e5%ad%a6%e9%a1%b9%e7%9b%ae/IDEA%20Project/mybatis/out/production/mybatis/pojo/UserQueryVo.class
DEBUG [main] - Reader entry: ����   4 %
DEBUG [main] - Checking to see if class pojo.Items matches criteria [is assignable to Object]
DEBUG [main] - Checking to see if class pojo.Order matches criteria [is assignable to Object]
DEBUG [main] - Checking to see if class pojo.OrderCustom matches criteria [is assignable to Object]
DEBUG [main] - Checking to see if class pojo.OrderDetail matches criteria [is assignable to Object]
DEBUG [main] - Checking to see if class pojo.User matches criteria [is assignable to Object]
DEBUG [main] - Checking to see if class pojo.UserCustom matches criteria [is assignable to Object]
DEBUG [main] - Checking to see if class pojo.UserQueryVo matches criteria [is assignable to Object]
DEBUG [main] - PooledDataSource forcefully closed/removed all connections.
DEBUG [main] - PooledDataSource forcefully closed/removed all connections.
DEBUG [main] - PooledDataSource forcefully closed/removed all connections.
DEBUG [main] - PooledDataSource forcefully closed/removed all connections.
DEBUG [main] - Find JAR URL: file:/E:/%e5%a4%a7%e5%ad%a6%e9%a1%b9%e7%9b%ae/IDEA%20Project/mybatis/out/production/mybatis/mapper
DEBUG [main] - Not a JAR: file:/E:/%e5%a4%a7%e5%ad%a6%e9%a1%b9%e7%9b%ae/IDEA%20Project/mybatis/out/production/mybatis/mapper
DEBUG [main] - Reader entry: OrderMapperCustom.class
DEBUG [main] - Reader entry: OrderMapperCustom.xml
DEBUG [main] - Reader entry: UserMapper.class
DEBUG [main] - Reader entry: UserMapper.xml
DEBUG [main] - Listing file:/E:/%e5%a4%a7%e5%ad%a6%e9%a1%b9%e7%9b%ae/IDEA%20Project/mybatis/out/production/mybatis/mapper
DEBUG [main] - Find JAR URL: file:/E:/%e5%a4%a7%e5%ad%a6%e9%a1%b9%e7%9b%ae/IDEA%20Project/mybatis/out/production/mybatis/mapper/OrderMapperCustom.class
DEBUG [main] - Not a JAR: file:/E:/%e5%a4%a7%e5%ad%a6%e9%a1%b9%e7%9b%ae/IDEA%20Project/mybatis/out/production/mybatis/mapper/OrderMapperCustom.class
DEBUG [main] - Reader entry: ����   4
DEBUG [main] - Find JAR URL: file:/E:/%e5%a4%a7%e5%ad%a6%e9%a1%b9%e7%9b%ae/IDEA%20Project/mybatis/out/production/mybatis/mapper/OrderMapperCustom.xml
DEBUG [main] - Not a JAR: file:/E:/%e5%a4%a7%e5%ad%a6%e9%a1%b9%e7%9b%ae/IDEA%20Project/mybatis/out/production/mybatis/mapper/OrderMapperCustom.xml
DEBUG [main] - Reader entry: <?xml version="1.0" encoding="UTF-8" ?>
DEBUG [main] - Find JAR URL: file:/E:/%e5%a4%a7%e5%ad%a6%e9%a1%b9%e7%9b%ae/IDEA%20Project/mybatis/out/production/mybatis/mapper/UserMapper.class
DEBUG [main] - Not a JAR: file:/E:/%e5%a4%a7%e5%ad%a6%e9%a1%b9%e7%9b%ae/IDEA%20Project/mybatis/out/production/mybatis/mapper/UserMapper.class
DEBUG [main] - Reader entry: ����   4    findUserByIdResultMap (I)Lpojo/User;
DEBUG [main] - Find JAR URL: file:/E:/%e5%a4%a7%e5%ad%a6%e9%a1%b9%e7%9b%ae/IDEA%20Project/mybatis/out/production/mybatis/mapper/UserMapper.xml
DEBUG [main] - Not a JAR: file:/E:/%e5%a4%a7%e5%ad%a6%e9%a1%b9%e7%9b%ae/IDEA%20Project/mybatis/out/production/mybatis/mapper/UserMapper.xml
DEBUG [main] - Reader entry: <?xml version="1.0" encoding="UTF-8" ?>
DEBUG [main] - Checking to see if class mapper.OrderMapperCustom matches criteria [is assignable to Object]
DEBUG [main] - Checking to see if class mapper.UserMapper matches criteria [is assignable to Object]
DEBUG [main] - Opening JDBC Connection
DEBUG [main] - Created connection 428910174.
DEBUG [main] - Setting autocommit to false on JDBC Connection [com.mysql.jdbc.JDBC4Connection@1990a65e]
DEBUG [main] - ==>  Preparing: select COUNT(*) from user WHERE user.sex = ? and user.username LIKE '%测试%'
DEBUG [main] - ==> Parameters: 1(String)
DEBUG [main] - <==      Total: 1
6

Process finished with exit code 0