多对多关联关系的映射与原理分析

最新推荐文章于 2025-05-04 16:49:23 发布

TorresFans

最新推荐文章于 2025-05-04 16:49:23 发布

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CC 4.0 BY-SA版权

文章标签： class string encoding table session null

本文链接：https://blog.youkuaiyun.com/fang3081004/article/details/7089473

本文详细介绍了如何使用Hibernate实现学生与教师之间的多对多关系，通过配置XML映射文件和Java代码，展示了如何创建、保存、关联学生和教师对象。

package com.messi.hibernate.test;

import java.util.HashSet;
import java.util.Set;
import org.hibernate.Session;
import org.hibernate.Transaction;
import com.messi.hibernate.domain.Student;
import com.messi.hibernate.domain.Teacher;
import com.messi.hibernate.utils.HibernateUtils;

public class Many2Many {

	public static void main(String[] args) {
        add();
	}

	static void add() {
		Session s = null;
		Transaction tx = null;
		try {
			Set<Teacher>ts=new HashSet<Teacher>();
			Teacher t1=new Teacher ();
			t1.setName("messi");
			
			Teacher t2=new Teacher ();
			t2.setName("Neymar");
			
			ts.add(t2);
			ts.add(t1);
			
			Set<Student> ss=new HashSet<Student>();
			Student s1=new Student();
			s1.setName("kaka");
			
			Student s2=new Student();
			s2.setName("cristiano");
			
			ss.add(s2);
			ss.add(s1);
			
			t1.setStudent(ss);
			t2.setStudent(ss);

			s = HibernateUtils.getSession();
			tx = s.beginTransaction();
			s.save(s2);
			s.save(s1);
			s.save(t1);
			s.save(t2);
			tx.commit();
		} finally {
			if (s != null) {
				s.close();
			}
		}

	}

}

teacher.hbm.xml:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.messi.hibernate.domain">
	<class name="Teacher">
		<id name="id">
			<generator class="native" />
		</id>
		<property name="name" />
		<set name="student" table="teacher_student">
			<key column="teacher_id" />
			<many-to-many class="Student" column="student_id" />
		</set>
	</class>
</hibernate-mapping>

student.hbm.xml:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.messi.hibernate.domain">
	<class name="Student">
		<id name="id">
			<generator class="native" />
		</id>
		<property name="name" />
		<set name="teacher" table="teacher_student">
			<key column="student_id" />
			<many-to-many class="Teacher" column="teacher_id" />
		</set>
	</class>
</hibernate-mapping>

Teacher.java:

package com.messi.hibernate.domain;

import java.util.Set;

public class Teacher {
	private int id;
	private String name; 
	private Set<Student> student;
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public Set<Student> getStudent() {
		return student;
	}
	public void setStudent(Set<Student> student) {
		this.student = student;
	}


}