Hibernate 一对多注解 实例

student：

/**
 *
 */
package com.wonders.task.sample.bo;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;

import org.hibernate.annotations.GenericGenerator;

/**
 * @ClassName: Student
 * @Description: TODO(这里用一句话描述这个类的作用)
 * @author zhoushun
 * @date 2014年2月27日 上午11:48:30
 *
 */

@Entity
@Table(name="Z_STUDENT")
public class Student {
	private String id;
	private String name;
	private Clazz clazz;

	@Id
	@GeneratedValue(generator="system-uuid")
	@GenericGenerator(name="system-uuid", strategy = "uuid")
	@Column(name = "ID")
	public String getId() {
		return id;
	}
	public void setId(String id) {
		this.id = id;
	}

	@Column(name = "NAME", length = 500)
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}

	@ManyToOne(cascade={CascadeType.ALL})
  	@JoinColumn(name="class_id")     //student类中对应外键的属性：classid
	public Clazz getClazz() {
		return clazz;
	}
	public void setClazz(Clazz clazz) {
		this.clazz = clazz;
	}

}

classes:

/**
 *
 */
package com.wonders.task.sample.bo;

import java.util.Set;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;

import org.hibernate.annotations.GenericGenerator;

/**
 * @ClassName: Clazz
 * @Description: TODO(这里用一句话描述这个类的作用)
 * @author zhoushun
 * @date 2014年2月27日 上午11:48:47
 *
 */
@Entity
@Table(name="Z_CLASS")
public class Clazz implements java.io.Serializable{
	/**
	 *
	 */
	private static final long serialVersionUID = -6224738252966513441L;
	private String id;
	private String name;
	private Set<Student> set;

	@Id
	@GeneratedValue(generator="system-uuid")
	@GenericGenerator(name="system-uuid", strategy = "uuid")
	@Column(name = "ID")
	public String getId() {
		return id;
	}
	public void setId(String id) {
		this.id = id;
	}

	@Column(name = "NAME", length = 500)
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}

	@OneToMany(cascade=CascadeType.ALL,mappedBy="clazz")
       //@OneToMany(cascade=CascadeType.ALL,mappedBy="clazz",fetch=FetchType.EAGER) 关闭延迟加载。    
	public Set<Student> getSet() {
		return set;
	}
	public void setSet(Set<Student> set) {
		this.set = set;
	}

}

main:

/**
 *
 */
package com.wonders.task.sample.main;

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

import javax.annotation.Resource;

import org.hibernate.Hibernate;
import org.hibernate.Session;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.Scope;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.orm.hibernate3.HibernateTemplate;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;

import com.wonders.schedule.util.SpringBeanUtil;
import com.wonders.task.sample.ITaskService;
import com.wonders.task.sample.bo.Clazz;
import com.wonders.task.sample.bo.Student;

/**
 * @ClassName: TestMain
 * @Description: TODO(这里用一句话描述这个类的作用)
 * @author zhoushun
 * @date 2014年2月27日 下午12:18:44
 *
 */

@Transactional(propagation = Propagation.REQUIRED, rollbackFor = Exception.class)
/* 功能模块入口点，beanid即数据库配置中的name */
@Service("testMain")
@Scope("prototype")
public class TestMain {
	private HibernateTemplate hibernateTemplate;

	public HibernateTemplate getHibernateTemplate() {
		return hibernateTemplate;
	}

	//注入hibernateTemplate
	@Resource(name="hibernateTemplate")
	public void setHibernateTemplate(HibernateTemplate hibernateTemplate) {
		this.hibernateTemplate = hibernateTemplate;
	}

	public void test(){
		Session session = this.getHibernateTemplate().getSessionFactory().getCurrentSession();
		Clazz c2 = (Clazz) session.get(Clazz.class, "8a81a97c4471c661014471c669360002");
		//Clazz c2 = (Clazz) main.getHibernateTemplate().get(Clazz.class, "8a81a97c4471c661014471c669360002");
		Hibernate.initialize(c2.getSet());

		System.out.println("11111111111111111111111");
		//session.close();
		Set<Student> sss =  c2.getSet();
		System.out.println("22222222222222222");
		for(Student s: sss){

			System.out.println(s.getName());
		}
	}

	public static void main(String[] args){
		ApplicationContext applicationContext = null;
		String[] fileUrl = new String[]{"classpath*:applicationContext*.xml"};
		applicationContext = new ClassPathXmlApplicationContext(fileUrl);  

		Student s1 = new Student();
		Student s2 = new Student();
		Clazz c1 = new Clazz();
		c1.setName("1班");
		s1.setName("z1");
		s1.setClazz(c1);
		s2.setName("z2");
		s2.setClazz(c1);
		Set<Student> set = new HashSet<Student>();
		set.add(s1);set.add(s2);
		c1.setSet(set);
		TestMain main = (TestMain)SpringBeanUtil.getBean("testMain");
		//main.getHibernateTemplate().save(c1);

//		Session session = main.getHibernateTemplate().getSessionFactory().openSession();
//		Clazz c2 = (Clazz) session.get(Clazz.class, "8a81a97c4471c661014471c669360002");
//		//Clazz c2 = (Clazz) main.getHibernateTemplate().get(Clazz.class, "8a81a97c4471c661014471c669360002");
//		Hibernate.initialize(c2.getSet());
//
//		System.out.println("11111111111111111111111");
//		session.close();
//		Set<Student> sss =  c2.getSet();
//		System.out.println("22222222222222222");
//		for(Student s: sss){
//
//			System.out.println(s.getName());
//		}
		main.test();
		//main.getHibernateTemplate().delete(c2);
	}
}

级联保存

方法1：自动维护两表关系，mappedby 为被拥维护方，即对应的student为维护方

Student s1 = new Student();
		Student s2 = new Student();
		Clazz c1 = new Clazz();
		c1.setName("1班");
		s1.setName("z1");
		s1.setClazz(c1);
		s2.setName("z2");
		s2.setClazz(c1);
		TestMain main = (TestMain)SpringBeanUtil.getBean("testMain");
		main.getHibernateTemplate().save(s1);
		main.getHibernateTemplate().save(s2);

方法2：手动维护，两方都需要set对应对方的变量

Student s1 = new Student();
		Student s2 = new Student();
		Clazz c1 = new Clazz();
		c1.setName("1班");
		s1.setName("z1");
		s1.setClazz(c1);
		s2.setName("z2");
		s2.setClazz(c1);
		Set<Student> set = new HashSet<Student>();
		set.add(s1);set.add(s2);
		c1.setSet(set);
		TestMain main = (TestMain)SpringBeanUtil.getBean("testMain");
		main.getHibernateTemplate().save(c1);

关于延迟加载：

http://blog.csdn.net/z69183787/article/details/20049409

http://blog.csdn.net/z69183787/article/details/17136627

关于mappedby关键字 及一对多 更多的解释：

http://blog.csdn.net/z69183787/article/details/8197106

http://blog.csdn.net/z69183787/article/details/18615577

再分享一下我老师大神的人工智能教程吧。零基础！通俗易懂！风趣幽默！还带黄段子！希望你也加入到我们人工智能的队伍中来！https://blog.csdn.net/jiangjunshow

原文地址：https://www.cnblogs.com/skinchqqhah/p/10350065.html