Hibernate中的get何load的区别

get和load的区别

1. 不存在对应记录时的表现不一样
2. load返回的是代理对象,等待真正用到对象内容时才发出sql请求
3. get直接从数据库加载,不会延迟

	@Test
	public void testLoadAndGet() {
		Session session = sf.getCurrentSession();
		session.beginTransaction();
		Teacher t = (Teacher)session.load(Teacher.class, 1);
		System.out.println(t.getName() + t.getId());
		session.getTransaction().commit();
	}

 

@Test
public void testLoadAndGet() {
	Session session = sf.getCurrentSession();
	session.beginTransaction();
	Teacher t = (Teacher)session.get(Teacher.class, 1);
	System.out.println(t.getName() + t.getId());
	session.getTransaction().commit();
}

 因为load是有延迟的,所以commit之后以下代码就会有错误

@Test
public void testLoadAndGet() {
	Session session = sf.getCurrentSession();
	session.beginTransaction();
	Teacher t = (Teacher)session.load(Teacher.class, 1);
	
	session.getTransaction().commit();
	System.out.println(t.getName() + t.getId());
}

 

16:52:42,859 ERROR LazyInitializationException:42 - could not initialize proxy - no Session
org.hibernate.LazyInitializationException: could not initialize proxy - no Session
	at org.hibernate.proxy.AbstractLazyInitializer.initialize(AbstractLazyInitializer.java:167)
	at org.hibernate.proxy.AbstractLazyInitializer.getImplementation(AbstractLazyInitializer.java:215)
	at org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer.invoke(JavassistLazyInitializer.java:191)
	at cn.neilone.model.Teacher_$$_javassist_0.getName(Teacher_$$_javassist_0.java)
	at cn.neilone.test.TeacherTest.testLoadAndGet(TeacherTest.java:80)

 

延迟初始化的错误