org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.engine

org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.engine.spi.CacheImplementor]
at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:271)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:233)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:210)
at org.hibernate.service.internal.SessionFactoryServiceRegistryImpl.getService(SessionFactoryServiceRegistryImpl.java:80)
at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:244)
at org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:452)
at org.hibernate.boot.internal.MetadataImpl.buildSessionFactory(MetadataImpl.java:170)
at com.yangm.utils.HibernateUtils.getSessionFactory(HibernateUtils.java:34)
at com.yangm.utils.HibernateUtils.getSession(HibernateUtils.java:44)
at com.yangm.testDriver.TestSessionFactory1.test(TestSessionFactory1.java:19)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:678)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)
Caused by: org.hibernate.cache.CacheException: net.sf.ehcache.CacheException: Another unnamed CacheManager already exists in the same VM. Please provide unique names for each CacheManager in the config or do one of following:
1. Use one of the CacheManager.create() static factory methods to reuse same CacheManager with same name or create one if necessary
2. Shutdown the earlier cacheManager before creating new one with same name.
The source of the existing CacheManager is: DefaultConfigurationSource [ ehcache.xml or ehcache-failsafe.xml ]
at org.hibernate.cache.ehcache.EhCacheRegionFactory.start(EhCacheRegionFactory.java:90)
at org.hibernate.cache.spi.RegionFactory.start(RegionFactory.java:63)
at org.hibernate.internal.CacheImpl.<init>(CacheImpl.java:71)
at org.hibernate.engine.spi.CacheInitiator.initiateService(CacheInitiator.java:28)
at org.hibernate.engine.spi.CacheInitiator.initiateService(CacheInitiator.java:20)
at org.hibernate.service.internal.SessionFactoryServiceRegistryImpl.initiateService(SessionFactoryServiceRegistryImpl.java:59)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:259)
... 32 more
Caused by: net.sf.ehcache.CacheException: Another unnamed CacheManager already exists in the same VM. Please provide unique names for each CacheManager in the config or do one of following:
1. Use one of the CacheManager.create() static factory methods to reuse same CacheManager with same name or create one if necessary
2. Shutdown the earlier cacheManager before creating new one with same name.
The source of the existing CacheManager is: DefaultConfigurationSource [ ehcache.xml or ehcache-failsafe.xml ]
at net.sf.ehcache.CacheManager.assertNoCacheManagerExistsWithSameName(CacheManager.java:626)
at net.sf.ehcache.CacheManager.init(CacheManager.java:391)
at net.sf.ehcache.CacheManager.<init>(CacheManager.java:269)
at org.hibernate.cache.ehcache.EhCacheRegionFactory.start(EhCacheRegionFactory.java:69)

... 38 more

我的工具类中获取session工厂的方法

public static SessionFactory  getSessionFactory() {
		final StandardServiceRegistry registry = new StandardServiceRegistryBuilder()
				.configure(). //加载 hibernate.cfg.xml配置文件。
				build();
		return new MetadataSources(registry).buildMetadata().buildSessionFactory();
	}

/**
	 * 获取HibernateSession的工具方法
	 * @return
	 */
	public static Session getSession() {
		
		
		//返回创建的session
		return getSessionFactory().openSession();
		
	}

测试代码

		@Test
		public void test() {
			
			Session session = HibernateUtils.getSession();
			Book book = session.get(Book.class, 1);
			System.out.println("book2======="+book);
			session.close();
			
			Session session2 = HibernateUtils.getSession();
			Book book2 = session2.get(Book.class, 1);
			System.out.println("book2======"+book2);
			System.out.println("book2?=book2--->"+(book==book2));
			session2.close();
		}

异常原因：

以上代码会创建两个session工厂。会去创建两个二级缓存。这是不允许的。

解决办法：

将获取工厂方法改为单例模式！

	static SessionFactory sessionFactory;
	static {
		//为应用建立一个Session工厂
		final StandardServiceRegistry registry = new StandardServiceRegistryBuilder()
				.configure(). //加载 hibernate.cfg.xml配置文件。
				build();	
		
		//建立Session工厂对象，类似于JDBC 连接池
		sessionFactory = new MetadataSources(registry).buildMetadata().buildSessionFactory();
			
	}