hibernate 多对多配置

最新推荐文章于 2022-11-22 11:52:35 发布

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文章标签：

#Hibernate #SSH #XML

本文介绍了一种基于Hibernate框架实现的教师与学生双向多对多关系映射的方法。通过创建Teacher和Student实体类及相应的数据库表，并配置XML映射文件，实现了教师与学生之间的关联。测试代码展示了如何初始化并保存教师和学生数据。

1. 创建表Teacher和Student和中间表teacher_student

CREATE TABLE `teacher` (               


              `tid` int(11) NOT NULL auto_increment,                 


              `name` varchar(50) NOT NULL, 


              PRIMARY KEY  (`tid`)                    


            ) ENGINE=InnoDB DEFAULT CHARSET=utf8;            





CREATE TABLE `student` (               


              `sid` int(11) NOT NULL auto_increment,                 


              `name` varchar(50) NOT NULL, 


              PRIMARY KEY  (`sid`)                    


            ) ENGINE=InnoDB DEFAULT CHARSET=utf8;            





create table teacher_student(


       tid int(11) not null,       


       sid int(11) not null


)ENGINE=InnoDB DEFAULT CHARSET=utf8;

2. 创建实体类 Teacher 和 Student

public class Student implements java.io.Serializable {

	// Fields

	private Integer sid;
	private String name;

	private Set<Teacher> teachers;
	// Constructors

	public Set<Teacher> getTeachers() {
		return teachers;
	}

	public void setTeachers(Set<Teacher> teachers) {
		this.teachers = teachers;
	}

	/** default constructor */
	public Student() {
	}

	/** full constructor */
	public Student(String name) {
		this.name = name;
	}

	// Property accessors

	public Integer getSid() {
		return this.sid;
	}

	public void setSid(Integer sid) {
		this.sid = sid;
	}

	public String getName() {
		return this.name;
	}

	public void setName(String name) {
		this.name = name;
	}

}

public class Teacher implements java.io.Serializable {

	// Fields

	private Integer tid;
	private String name;
	
	private Set<Student> stus;
	
	// Constructors

	public Set<Student> getStus() {
		return stus;
	}

	public void setStus(Set<Student> stus) {
		this.stus = stus;
	}

	/** default constructor */
	public Teacher() {
	}

	/** full constructor */
	public Teacher(String name) {
		this.name = name;
	}

	// Property accessors

	public Integer getTid() {
		return this.tid;
	}

	public void setTid(Integer tid) {
		this.tid = tid;
	}

	public String getName() {
		return this.name;
	}

	public void setName(String name) {
		this.name = name;
	}

}

3. 配置Teacher.hbm.xml 和 student.hbm.xml配置文件

Teacher.hbm.xml

<hibernate-mapping>
    <class name="ssh.pojo.Teacher" table="teacher" catalog="zf">
        <id name="tid" type="java.lang.Integer">
            <column name="tid" />
            <generator class="native" />
        </id>
        <property name="name" type="java.lang.String">
            <column name="name" length="50" not-null="true" />
        </property>
        <set name="stus" table="teacher_student" cascade="save-update" inverse="true">
        	<key column="tid"></key>
        	<many-to-many column="sid" class="ssh.pojo.Student"></many-to-many>
        </set>
    </class>
</hibernate-mapping>

Student.hbm.xml

<hibernate-mapping>
    <class name="ssh.pojo.Student" table="student" catalog="zf">
        <id name="sid" type="java.lang.Integer">
            <column name="sid" />
            <generator class="native" />
        </id>
        <property name="name" type="java.lang.String">
            <column name="name" length="50" not-null="true" />
        </property>
        <set name="teachers" table="teacher_student" cascade="save-update">
        	<key column="sid"></key>
        	<many-to-many column="tid" class="ssh.pojo.Teacher"></many-to-many>
        </set>
    </class>
</hibernate-mapping>

4. 测试

Session session = null;  // 一级缓存
		TblUser user = null;
		try{
			session = HibernateSessionFactory.getSession();
			session.beginTransaction();
			
			Set<Teacher> teachers = new HashSet<Teacher>();
			Set<Student> students = new HashSet<Student>();
			// 初始化老师
			Teacher tWang = new Teacher();
			tWang.setName("王");
			Teacher tZhang = new Teacher();
			tZhang.setName("张");
			teachers.add(tWang);
			teachers.add(tZhang);
			// 初始化学生
			Student s1 = new Student();
			Student s2 = new Student();
			Student s3 = new Student();
			s1.setName("刘另一");
			s2.setName("任汉卿");
			s3.setName("付博文");
			students.add(s1);
			students.add(s2);
			students.add(s3);
			
			// teacher--->stu
			tWang.setStus(students);
			tZhang.setStus(students);
			// stu---->teacher
			s1.setTeachers(teachers);
			s2.setTeachers(teachers);
			s3.setTeachers(teachers);
			
			// save to db
			session.save(tWang);
			session.save(tZhang);
			session.save(s1);
			session.save(s2);
			session.save(s3);
			
			
			session.getTransaction().commit();
		}catch(Exception e){
			e.printStackTrace();
			session.getTransaction().rollback();
		}
结果：
Hibernate: insert into zf.teacher (name) values (?)
Hibernate: insert into zf.student (name) values (?)
Hibernate: insert into zf.teacher (name) values (?)
Hibernate: insert into zf.student (name) values (?)
Hibernate: insert into zf.student (name) values (?)
Hibernate: insert into teacher_student (sid, tid) values (?, ?)
Hibernate: insert into teacher_student (sid, tid) values (?, ?)
Hibernate: insert into teacher_student (sid, tid) values (?, ?)
Hibernate: insert into teacher_student (sid, tid) values (?, ?)
Hibernate: insert into teacher_student (sid, tid) values (?, ?)
Hibernate: insert into teacher_student (sid, tid) values (?, ?)