多对多的单向关联

一个老师（Teacher）教多个学生（Student），一个学生（Student）可以有多名老师（Teacher），这就是一对一的关系，下面以这个例子为例进行配置：

　　Annotataion 配置：

　　　　Teacher:

　　　　　　

 1 package com.bjsxt.hibernate;
 2 
 3 import java.util.HashSet;
 4 import java.util.Set;
 5 
 6 import javax.persistence.Entity;
 7 import javax.persistence.GeneratedValue;
 8 import javax.persistence.Id;
 9 import javax.persistence.JoinColumn;
10 import javax.persistence.JoinTable;
11 import javax.persistence.ManyToMany;
12 import javax.persistence.Table;
13 
14 @Entity
15 @Table(name="t_teacher")
16 public class Teacher {
17     
18     private Integer id;
19     
20     private String name;
21     
22     private Set<Student> students = new HashSet<Student>();
23 
24     @Id
25     @GeneratedValue
26     public Integer getId() {
27         return id;
28     }
29 
30     public void setId(Integer id) {
31         this.id = id;
32     }
33 
34     public String getName() {
35         return name;
36     }
37 
38     public void setName(String name) {
39         this.name = name;
40     }
41 
42     @ManyToMany
43     @JoinTable(name="t_s",
44         joinColumns={@JoinColumn(name="teacher_id")},
45         inverseJoinColumns={@JoinColumn(name="student_id")}
46     )
47     public Set<Student> getStudents() {
48         return students;
49     }
50 
51     public void setStudents(Set<Student> students) {
52         this.students = students;
53     }
54 
55 }

　　　　　　Student:　　　　　　　　

 1 package com.bjsxt.hibernate;
 2 
 3 import javax.persistence.Entity;
 4 import javax.persistence.GeneratedValue;
 5 import javax.persistence.Id;
 6 import javax.persistence.Table;
 7 
 8 @Entity
 9 @Table(name="t_student")
10 public class Student {
11     private Integer id;
12     
13     private String name;
14     
15     @Id
16     @GeneratedValue
17     public Integer getId() {
18         return id;
19     }
20 
21     public void setId(Integer id) {
22         this.id = id;
23     }
24 
25     public String getName() {
26         return name;
27     }
28 
29     public void setName(String name) {
30         this.name = name;
31     }
32 }

　　XML 配置：

　　　　　　Teacher.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="com.bjsxt.hibernate">
    <class name="Teacher" table="t_teacher">
        <id name="id" column="id">
            <generator class="native"/>
        </id>
        <property name="name" column="name" />
        <set name="students" table="t_s">
            <key column="teacher_id"></key><!-- 指定自己这张表在中间表的列名 -->
            <many-to-many class="Student" column="student_id" /><!-- 指定多对多的那张表在中间表的列名 -->
        </set>
    </class>
</hibernate-mapping>

　　　　　　Student.hbm.xml

 1 <?xml version="1.0"?>
 2 <!DOCTYPE hibernate-mapping PUBLIC
 3         "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
 4         "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
 5 
 6 <hibernate-mapping package="com.bjsxt.hibernate">
 7     <class name="Student" table="t_student">
 8         <id name="id" column="id">
 9             <generator class="native"/>
10         </id>
11         <property name="name" column="name" />
12     </class>
13 </hibernate-mapping>

上面两种方式，生成SQL的结果一样，生成顺序：

jar链接: https://pan.baidu.com/s/1eSKKZ8Q 密码: puad

代码链接: https://pan.baidu.com/s/1bpxk8H5 密码: e7ku

posted @ 2017-04-21 10:25  流年如水烟雨随风  阅读(1108)  评论(0)  编辑  收藏  举报