hibernate單向N-N關係映射

創建一個小的例子：

1、創建數據庫本例使用sql sever 2008 r2數據庫。

Teacher—student表：

Teacher表

student表

2、在myeclipse中使用反向工程生成實體類

student實體類代碼

package com.wxb.model;

import java.util.HashSet;
import java.util.Set;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;

import static javax.persistence.GenerationType.IDENTITY;

import javax.persistence.Id;
import javax.persistence.Table;

/**
 * Student entity.
 * @author 王校兵
 * @version 1.0,2015-11-28
 */
@Entity
@Table(name = "Student")
public class Student implements java.io.Serializable {

	// Fields

	private Integer sid;
	private String sname;
	private Set<Teacher> teacher = new HashSet<Teacher>();

	// Constructors

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

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

	// Property accessors
	@Id
	@GeneratedValue(strategy = IDENTITY)
	@Column(name = "Sid")
	public Integer getSid() {
		return this.sid;
	}

	@Column(name = "Sname", nullable = false)
	public String getSname() {
		return this.sname;
	}

	// 定義該Person實體所有關聯的Address實體
	@ManyToMany(targetEntity = Teacher.class)
	// 映射連接表爲Teacher_Student
	@JoinTable(name = "Teacher_Student",
		// 定義連接表中名爲person_id的外鍵列，該外鍵列參照當前實體對應表的主鍵列
		joinColumns ={ @JoinColumn(name = "Sid") },
		//翻轉與
		inverseJoinColumns = @JoinColumn(name = "Tid")
	)
	public Set<Teacher> getTeacher() {
		return teacher;
	}

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

	public void setSname(String sname) {
		this.sname = sname;
	}

	public void setTeacher(Set<Teacher> teacher) {
		this.teacher = teacher;
	}

}

teacher表

package com.wxb.model;

import java.util.HashSet;
import java.util.Set;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;

import static javax.persistence.GenerationType.IDENTITY;

import javax.persistence.Id;
import javax.persistence.Table;

/**
 * Teacher entity.
 * @author 王校兵
 * @version 1.0,2015-11-28
 */
@Entity
@Table(name = "Teacher")
public class Teacher implements java.io.Serializable {

	// Fields

	private Integer tid;
	private String tname;
//	private Set<Student> student = new HashSet<Student>();

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

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

	@Id
	@GeneratedValue(strategy = IDENTITY)
	@Column(name = "Tid", unique = true, nullable = false)
	public Integer getTid() {
		return this.tid;
	}

	@Column(name = "Tname", nullable = false)
	public String getTname() {
		return this.tname;
	}

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

	public void setTname(String tname) {
		this.tname = tname;
	}

}

3、實現單向多對多測試類

向數據庫中插入數據測試

package com.wxb.dao;

import org.hibernate.Session;
import org.hibernate.Transaction;

import com.wxb.model.Student;
import com.wxb.model.Teacher;
import com.wxb.util.HibernateSessionFactory;

/**
 * 單向多對多關聯映射測試類
 * @author 王校兵
 * @version 1.0, 2015-11-28
 * */
public class SingleNToNDao {
	public static void main(String[] args) {
		Session session = HibernateSessionFactory.getSession();
		Transaction ts = session.beginTransaction();
		
		Student s = new Student();
		s.setSname("測試");
		
		session.save(s);
		
		
		Teacher t1 = new Teacher();
		Teacher t2 = new Teacher();
		Teacher t3 = new Teacher();
		
		t1.setTname("1");
		t2.setTname("2");
		t3.setTname("3");
		
		s.getTeacher().add(t1);
		session.save(t1);
		
		s.getTeacher().add(t2);
		session.save(t2);
		
		ts.commit();
		
		
	}
}

讀取數據庫中的dao

package com.wxb.dao;

import org.hibernate.Session;
import org.hibernate.Transaction;

import com.wxb.model.Student;
import com.wxb.model.Teacher;
import com.wxb.util.HibernateSessionFactory;

/**
 * 單向一對多關係映射測試類
 * @author 王校兵
 * @version 1.0, 2015-11-28
 * */
public class ReadSingleNToNDao {
	public static void main(String[] args) {
		Session session = HibernateSessionFactory.getSession();
		Transaction ts = session.beginTransaction();
		Student s = (Student)session.get(Student.class, 2);
		
		System.out.println(s.getSname());
		
		for(Teacher t:s.getTeacher()){
			System.out.println(t.getTname());
		}
		
		
		Teacher tt = (Teacher) session.get(Teacher.class, 3);
		
		System.out.println(tt.getTname());
		
	}
}

經過上述過程即可實現單向多對多的關係映射測試。