Hibernate4多对多关系映射

示例：一个老师（Teacher）有多个学生（Student），一个学生有多个老师。

public class Teacher {

	private Integer id;
	private String name;

	private Set<Student> students = new HashSet<Student>();

	// getter and setter
}	

 

public class Student {

	private Integer id;
	private String name;
	
	private Set<Teacher> teachers = new HashSet<Teacher>();

	// getter and setter
}

 用XML映射

<hibernate-mapping package="org.monday.hibernate4.domain">
	<class name="Teacher" table="tbl_teacher">
		<id name="id">
			<generator class="identity" />
		</id>
		<property name="name" />
		<set name="students" table="tbl_student_teacher">
			<key column="teacher_id" />
			<many-to-many class="Student" column="student_id" />
		</set>
	</class>
</hibernate-mapping>

 

<hibernate-mapping package="org.monday.hibernate4.domain">
	<class name="Student" table="tbl_student">
		<id name="id">
			<generator class="identity" />
		</id>
		<property name="name" />
		<set name="teachers" table="tbl_student_teacher" inverse="true">
			<key column="student_id" />
			<many-to-many class="Teacher" column="teacher_id" />
		</set>
	</class>
</hibernate-mapping>

 

 用@Annotation映射

@Entity
@Table(name = "tbl_teacher")
public class Teacher {

	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	private Integer id;
	private String name;

	@ManyToMany
	@JoinTable(name = "tbl_student_teacher", joinColumns = @JoinColumn(name = "teacher_id"), inverseJoinColumns = @JoinColumn(name = "student_id"))
	private Set<Student> students = new HashSet<Student>();

	// getter and setter
}

 

@Entity
@Table(name = "tbl_student")
public class Student {

	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	private Integer id;
	private String name;

	@ManyToMany(mappedBy = "students")
	private Set<Teacher> teachers = new HashSet<Teacher>();

	// getter and setter
}

 @ManyToMany中增加mappedBy属性的实体将不再控制关联关系 

 

测试代码

Student s = new Student();
s.setName("terry");

Teacher t = new Teacher();
t.setName("mary");

t.getStudents().add(s);
s.getTeachers().add(t);

session.save(t);
session.save(s);

 

 SQL schema

Hibernate: 
    create table tbl_student (
        id integer not null auto_increment,
        name varchar(255),
        primary key (id)
    )
Hibernate: 
    create table tbl_student_teacher (
        teacher_id integer not null,
        student_id integer not null,
        primary key (teacher_id, student_id)
    )
Hibernate: 
    create table tbl_teacher (
        id integer not null auto_increment,
        name varchar(255),
        primary key (id)
    )
Hibernate: 
    alter table tbl_student_teacher 
        add index FK2BB635DB556D6E8 (teacher_id), 
        add constraint FK2BB635DB556D6E8 
        foreign key (teacher_id) 
        references tbl_teacher (id)
Hibernate: 
    alter table tbl_student_teacher 
        add index FK2BB635DA4BB8C48 (student_id), 
        add constraint FK2BB635DA4BB8C48 
        foreign key (student_id) 
        references tbl_student (id)
Hibernate: 
    insert 
    into
        tbl_teacher
        (name) 
    values
        (?)
Hibernate: 
    insert 
    into
        tbl_student
        (name) 
    values
        (?)
Hibernate: 
    insert 
    into
        tbl_student_teacher
        (teacher_id, student_id) 
    values
        (?, ?)