1 package com.haifei.domain;
 2 
 3 import java.util.Date;
 4 import java.util.List;
 5 
 6 /**
 7  * user表
 8  */
 9 public class User {
10 
11     private int id;
12     private String username;
13     private String password;
14     private Date birthday;
15 
16     //描述的是當前使用者存在哪些訂單
17     private List<Order> orderList;
 
18     public List<Order> getOrderList() {
19         return orderList;
20     }
21     public void setOrderList(List<Order> orderList) {
22         this.orderList = orderList;
23     }
24 
25 
26     public Date getBirthday() {
27         return birthday;
28     }
29 
30     public void setBirthday(Date birthday) {
 
31         this.birthday = birthday;
32     }
33 
34     public int getId() {
35         return id;
36     }
37 
38     public void setId(int id) {
39         this.id = id;
40     }
41 
42     public String getUsername() {
43         return username;
44     }
45 
46     public void setUsername(String username) {
 
47         this.username = username;
48     }
49 
50     public String getPassword() {
51         return password;
52     }
53 
54     public void setPassword(String password) {
55         this.password = password;
56     }
57 
58    
59     //1:n
60     @Override
61     public String toString() {
62         return "User{" +
63                 "id=" + id +
64                 ", username='" + username + '\'' +
65                 ", password='" + password + '\'' +
66                 ", birthday=" + birthday +
67                 ", orderList=" + orderList +
68                 '}';
69     }
70     
71 }

 1 package com.haifei.mapper;
 2 
 3 import com.haifei.domain.User;
 4 
 5 import java.util.List;
 6 
 7 public interface UserMapper {
 8 
 9     public List<User> findAll();
10 
11 }

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
 3 
 4 <mapper namespace="com.haifei.mapper.UserMapper">
 5 
 6     <resultMap id="userMap" type="user">
 7         <!--user的資訊-->
 8         <id column="uid" property="id"/>
 9         <result column="username" property="username"/>
10         <result column="password" property="password"/>
11         <result column="birthday" property="birthday"/>
12         <!--user內部的orderList資訊-->
13         <collection property="orderList" ofType="order">
14             <!--配置集合資訊,property:集合名稱,ofType：當前集合中的資料型別-->
15             <!--封裝order的資料-->
16             <id column="oid" property="id"/>
17             <result column="ordertime" property="ordertime"/>
18             <result column="total" property="total"/>
19         </collection>
20     </resultMap>
21 
22     <select id="findAll" resultMap="userMap">
23         SELECT *,o.id oid FROM user u,orders o WHERE u.id=o.uid
24     </select>
25 
26    
27 </mapper>

 1 /**
 2      * 一對多查詢
 3      *  場景：一個使用者有多個訂單
 4      * @throws IOException
 5      */
 6     @Test
 7     public void test2() throws IOException {
 8         InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");
 9         SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
10         SqlSession sqlSession = sqlSessionFactory.openSession();
11 
12         UserMapper mapper = sqlSession.getMapper(UserMapper.class);
13         List<User> userList = mapper.findAll();
14         for (User user : userList) {
15             System.out.println(user);
16         }
17         /*
18         User{id=1, username='zhangsan', password='123', birthday=Sat Jul 24 20:00:29 CST 2021, orderList=[Order{id=1, ordertime=Thu Jan 01 08:00:02 CST 1970, total=3000.0, user=null}, Order{id=3, ordertime=Thu Jan 01 08:00:02 CST 1970, total=344.0, user=null}]}
19         User{id=2, username='lisi', password='345', birthday=Sat Jul 24 20:00:29 CST 2021, orderList=[Order{id=2, ordertime=Thu Jan 01 08:00:02 CST 1970, total=1000.0, user=null}, Order{id=4, ordertime=Thu Jan 01 08:00:02 CST 1970, total=455.0, user=null}]}
20         User{id=3, username='tom', password='abc', birthday=Sat Jul 24 20:00:29 CST 2021, orderList=[Order{id=5, ordertime=Thu Jan 01 08:00:02 CST 1970, total=100.0, user=null}]}
21          */
22 
23         sqlSession.close();
24     }