myeclipse中hibernate出错

执行Session session11 = HibernateSessionFactory.getSession();// 获得一个Session,,在用完之后我们、要友好的关闭session
的时候出错：解决办法tomcat下lib下缺少ehcache.jar 

java.lang.NoClassDefFoundError: net/sf/ehcache/CacheException
 at java.lang.Class.getDeclaredConstructors0(Native Method)
 at java.lang.Class.privateGetDeclaredConstructors(Unknown Source)
 at java.lang.Class.getConstructor0(Unknown Source)
 at java.lang.Class.newInstance0(Unknown Source)
 at java.lang.Class.newInstance(Unknown Source)
 at org.hibernate.cfg.SettingsFactory.createCacheProvider(SettingsFactory.java:327)
 at org.hibernate.cfg.SettingsFactory.buildSettings(SettingsFactory.java:219)
 at org.hibernate.cfg.Configuration.buildSettings(Configuration.java:1859)
 at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1152)
 at org.jbpm.persistence.db.DbPersistenceServiceFactory.getSessionFactory(DbPersistenceServiceFactory.java:91)
 at org.jbpm.persistence.db.DbPersistenceService.getSessionFactory(DbPersistenceService.java:76)
 at org.jbpm.persistence.db.DbPersistenceService.getSession(DbPersistenceService.java:80)
 at org.jbpm.persistence.db.DbPersistenceService.getGraphSession(DbPersistenceService.java:234)
 at org.jbpm.JbpmContext.getGraphSession(JbpmContext.java:539)
 at org.jbpm.JbpmContext.deployProcessDefinition(JbpmContext.java:173)
 at com.sample.SimpleProcessTest.testSimpleProcess(SimpleProcessTest.java:23)
 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 junit.framework.TestCase.runTest(TestCase.java:154)
 at junit.framework.TestCase.runBare(TestCase.java:127)
 at junit.framework.TestResult$1.protect(TestResult.java:106)
 at junit.framework.TestResult.runProtected(TestResult.java:124)
 at junit.framework.TestResult.run(TestResult.java:109)
 at junit.framework.TestCase.run(TestCase.java:118)
 at junit.framework.TestSuite.runTest(TestSuite.java:208)
 at junit.framework.TestSuite.run(TestSuite.java:203)
 at org.eclipse.jdt.internal.junit.runner.junit3.JUnit3TestReference.run(JUnit3TestReference.java:128)
 at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:460)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:673)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:386)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:196)