和多對一單向關聯類似，但是雙向關聯需要在關聯的兩方都添加配置。實體類和配置文件如下，還是以老師和學生為例。
Student
1 package domain;
2
3
4 public class Student {
5
6 private int id;
7 private String name;
8 private String grade;
9
10 private Teacher teacher;
11
12 //get/set和構造省略，但實際不可省
13
14 }
15
1 <?xml version="1.0"?>
2 <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
3 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
4
5 <hibernate-mapping>
6 <class name="domain.Student" table="STUDENT">
7 <id name="id" type="int">
8 <column name="ID" />
9 <generator class="native" />
10 </id>
11 <property name="name" type="java.lang.String">
12 <column name="NAME" />
13 </property>
14 <property name="grade" type="java.lang.String">
15 <column name="GRADE" />
16 </property>
17 <many-to-one name="teacher" class="domain.Teacher" fetch="join">
18 <!-- 指定對方的外鍵 -->
19 <column name="tid" />
20 </many-to-one>
21 </class>
22 </hibernate-mapping>
23
Teacher
1 package domain;
2
3 import java.util.HashSet;
4 import java.util.Set;
5
6 public class Teacher {
7
8 private int id;
9 private String name;
10 private String course;
11
12 private Set<Student> students;
13
14 //get/set和構造省略，但實際不可省
15
16 }
17
1 <?xml version="1.0"?>
2 <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
3 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
4
5 <hibernate-mapping>
6 <class name="domain.Teacher" table="TEACHER">
7 <id name="id" type="int">
8 <column name="ID" />
9 <generator class="native" />
10 </id>
11 <property name="name" type="java.lang.String">
12 <column name="NAME" />
13 </property>
14 <property name="course" type="java.lang.String">
15 <column name="COURSE" />
16 </property>
17 <!-- lazy extra會增強查詢的功能，根據查詢的內容選擇查詢語句，比如查詢集合的數量會使用select count(*) -->
18 <!-- inverse true表示由對方來維護關聯關系，也就是說，在學生對象設置老師屬性并保存之后，二者的關系會建立，教師不負責維護關系 -->
19 <set name="students" lazy="extra" inverse="true">
20 <key>
21 <!-- 指定需要關聯的外鍵，應和Student的設置一致 -->
22 <column name="tid" />
23 </key>
24 <one-to-many class="domain.Student"/>
25 </set>
26 </class>
27 </hibernate-mapping>
28
書寫測試類
1 package demo;
2
3 import org.hibernate.Session;
4 import org.junit.Test;
5
6 import domain.Student;
7 import domain.Teacher;
8 import util.HibernateUtil;
9
10
11 public class App
12 {
13 @Test
14 /**
15 * oneToMany雙向關聯，設置多的一方維護關系。最佳實踐就是：先添加一的一方，之后再添加多的一方
16 * 這樣不會造成冗余的sql
17 */
18 public void addTest() {
19 Session session = null;
20 try {
21 session = HibernateUtil.openSession();
22 session.beginTransaction();
23
24 //添加一的一方
25 Teacher teacher = new Teacher();
26 teacher.setName("張老師");
27 teacher.setCourse("物理");
28 session.save(teacher);
29
30 //添加多的一方，設置一的一方，因為多的一方需要維護關系
31 Student stu1 = new Student();
32 stu1.setName("小明");
33 stu1.setGrade("一");
34 stu1.setTeacher(teacher);
35 session.save(stu1);
36
37 Student stu2 = new Student();
38 stu2.setName("小紅");
39 stu2.setGrade("二");
40 stu2.setTeacher(teacher);
41 session.save(stu2);
42
43 session.getTransaction().commit();
44
45 } catch (Exception e) {
46 if (session != null) {
47 session.getTransaction().rollback();
48 }
49 } finally{
50 if (session != null) {
51 session.close();
52 }
53 }
54 }
55 }
56