我使用JSF，MySQL和NetBeans（web-app模板设计）创建了一个Web应用程序。
这是我得到的错误跟踪：http://adelazzam.com/errorTrace.htm
javax.persistence.PersistenceException: Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.0.1.v20100213-r6600): org.eclipse.persistence.exceptions.DatabaseException
Internal Exception: java.sql.SQLException: Error in allocating a connection. Cause: null
Error Code: 0
at org.eclipse.persistence.internal.jpa.EntityManagerSetupImpl.deploy(EntityManagerSetupImpl.java:397)
at org.eclipse.persistence.internal.jpa.EntityManagerFactoryImpl.getServerSession(EntityManagerFactoryImpl.java:151)
at org.eclipse.persistence.internal.jpa.EntityManagerFactoryImpl.createEntityManagerImpl(EntityManagerFactoryImpl.java:207)
at org.eclipse.persistence.internal.jpa.EntityManagerFactoryImpl.createEntityManager(EntityManagerFactoryImpl.java:202)
at com.sun.enterprise.container.common.impl.EntityManagerWrapper._getDelegate(EntityManagerWrapper.java:207)
at com.sun.enterprise.container.common.impl.EntityManagerWrapper.getCriteriaBuilder(EntityManagerWrapper.java:883)
at jpa.session.AbstractFacade.count(AbstractFacade.java:56)
at jsf.ToolController.getPagingInfo(ToolController.java:45)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at javax.el.BeanELResolver.getValue(BeanELResolver.java:302)
at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:175)
at com.sun.faces.el.FacesCompositeELResolver.getValue(FacesCompositeELResolver.java:72)
at com.sun.el.parser.AstValue.getValue(AstValue.java:116)
at com.sun.el.parser.AstValue.getValue(AstValue.java:163)
at com.sun.el.parser.AstEqual.getValue(AstEqual.java:54)
at com.sun.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:219)
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:190)
at javax.faces.component.UIComponentBase.isRendered(UIComponentBase.java:416)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1607)
at javax.faces.render.Renderer.encodeChildren(Renderer.java:168)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:848)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1613)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1616)
at com.sun.faces.application.view.JspViewHandlingStrategy.doRenderView(JspViewHandlingStrategy.java:420)
at com.sun.faces.application.view.JspViewHandlingStrategy.renderView(JspViewHandlingStrategy.java:209)
at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:126)
at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:127)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:313)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1523)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:279)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:188)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:641)
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:97)
at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:85)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:185)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:325)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:226)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:165)
at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:791)
at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:693)
at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:954)
at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:170)
at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:135)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:102)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:88)
at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:76)
at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:53)
at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:57)
at com.sun.grizzly.ContextTask.run(ContextTask.java:69)
at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:330)
at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:309)
at java.lang.Thread.run(Thread.java:619)
Caused by: Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.0.1.v20100213-r6600): org.eclipse.persistence.exceptions.DatabaseException
Internal Exception: java.sql.SQLException: Error in allocating a connection. Cause: null
Error Code: 0
at org.eclipse.persistence.exceptions.DatabaseException.sqlException(DatabaseException.java:309)
at org.eclipse.persistence.sessions.JNDIConnector.connect(JNDIConnector.java:138)
at org.eclipse.persistence.sessions.JNDIConnector.connect(JNDIConnector.java:94)
at org.eclipse.persistence.sessions.DatasourceLogin.connectToDatasource(DatasourceLogin.java:162)
at org.eclipse.persistence.internal.sessions.DatabaseSessionImpl.loginAndDetectDatasource(DatabaseSessionImpl.java:584)
at org.eclipse.persistence.internal.jpa.EntityManagerFactoryProvider.login(EntityManagerFactoryProvider.java:228)
at org.eclipse.persistence.internal.jpa.EntityManagerSetupImpl.deploy(EntityManagerSetupImpl.java:369)
... 56 more
Caused by: java.sql.SQLException: Error in allocating a connection. Cause: null
at com.sun.gjc.spi.base.DataSource.getConnection(DataSource.java:112)
at org.eclipse.persistence.sessions.JNDIConnector.connect(JNDIConnector.java:126)
... 61 more
原因是什么以及如何解决？
答案 0 :(得分：2)
如果是大型堆栈跟踪，请始终前往最后一个以查找真正的根本原因：
引起：java.sql.SQLException：分配连接时出错。原因：null
因此，无法从数据源获得连接。显然，数据源本身是null。您需要在Glassfish中创建MySQL数据源。有几种方法：