hibernate 懒加载问题的一个临时解决方案

Hibernate懒加载

最新推荐文章于 2021-07-22 16:00:22 发布

原创最新推荐文章于 2021-07-22 16:00:22 发布 · 233 阅读

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#XML #Hibernate

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本文探讨了Hibernate框架中懒加载机制的问题及解决方案，介绍了如何通过Hibernate.initialize()方法强制初始化延迟加载的对象，但该方法不支持递归加载。此外，还强调了正确的类设计与XML配置对于解决懒加载问题的重要性。

hibernate的懒加载问题时常会困扰着我们，今天发现了hibernate自身也提供一些解决办法

Hibernate.initialize(company.getUsers()); 这样就加载了users集合

但不支持递归加载

 it is not guaranteed that the elements INSIDE the collection will be initialized/materialized

假如这时session关闭了会报错

真正解决懒加载还是应该在类的设计 xml文件的配置上下功夫

源码：

	/**
	 * Force initialization of a proxy or persistent collection.
	 * <p/>
	 * Note: This only ensures intialization of a proxy object or collection;
	 * it is not guaranteed that the elements INSIDE the collection will be initialized/materialized.
	 *
	 * @param proxy a persistable object, proxy, persistent collection or <tt>null</tt>
	 * @throws HibernateException if we can't initialize the proxy at this time, eg. the <tt>Session</tt> was closed
	 */
	public static void initialize(Object proxy) throws HibernateException {
		if ( proxy == null ) {
			return;
		}
		else if ( proxy instanceof HibernateProxy ) {
			( ( HibernateProxy ) proxy ).getHibernateLazyInitializer().initialize();
		}
		else if ( proxy instanceof PersistentCollection ) {
			( ( PersistentCollection ) proxy ).forceInitialization();
		}
	}

	/**
	 * Check if the proxy or persistent collection is initialized.
	 *
	 * @param proxy a persistable object, proxy, persistent collection or <tt>null</tt>
	 * @return true if the argument is already initialized, or is not a proxy or collection
	 */
	public static boolean isInitialized(Object proxy) {
		if ( proxy instanceof HibernateProxy ) {
			return !( ( HibernateProxy ) proxy ).getHibernateLazyInitializer().isUninitialized();
		}
		else if ( proxy instanceof PersistentCollection ) {
			return ( ( PersistentCollection ) proxy ).wasInitialized();
		}
		else {
			return true;
		}
	}