创建servlet出错

Question

an error has occurred when create servlet finished
java.lang.Error: Unresolved compilation problems: 
The import org.eclipse.jst.j2ee.internal.common cannot be resolved
CreateServletTemplateModel cannot be resolved to a type
CreateServletTemplateModel cannot be resolved to a type
CreateJavaEEArtifactTemplateModel cannot be resolved
CreateServletTemplateModel cannot be resolved
CreateServletTemplateModel cannot be resolved
CreateServletTemplateModel cannot be resolved
Constructor cannot be resolved to a type
Constructor cannot be resolved to a type
Method cannot be resolved to a type
at org.eclipse.jst.j2ee.internal.web.operations.ServletTemplate_.<init>(ServletTemplate_.java:4) at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27) at java.lang.reflect.Constructor.newInstance(Constructor.java:494) at java.lang.Class.newInstance0(Class.java:350) at java.lang.Class.newInstance(Class.java:303) at org.eclipse.emf.codegen.jet.JETEmitter.setMethod(JETEmitter.java:291) at org.eclipse.jst.j2ee.internal.project.WTPJETEmitter.loadClass(WTPJETEmitter.java:387) at org.eclipse.jst.j2ee.internal.project.WTPJETEmitter.initialize(WTPJETEmitter.java:234) at org.eclipse.jst.j2ee.internal.project.WTPJETEmitter.<init>(WTPJETEmitter.java:114) at org.eclipse.jst.j2ee.internal.common.operations.NewJavaEEArtifactClassOperation.generateTemplateSource(NewJavaEEArtifactClassOperation.java:244) at org.eclipse.jst.j2ee.internal.common.operations.NewJavaEEArtifactClassOperation.generateTemplateSource(NewJavaEEArtifactClassOperation.java:182) at org.eclipse.jst.j2ee.internal.web.operations.NewWebClassOperation.generateUsingTemplates(NewWebClassOperation.java:129) at org.eclipse.jst.j2ee.internal.common.operations.NewJavaEEArtifactClassOperation.doExecute(NewJavaEEArtifactClassOperation.java:99) at org.eclipse.jst.j2ee.internal.common.operations.NewJavaEEArtifactClassOperation.execute(NewJavaEEArtifactClassOperation.java:69) at org.eclipse.jst.j2ee.internal.common.operations.AddJavaEEArtifactOperation.createClass(AddJavaEEArtifactOperation.java:70) at org.eclipse.jst.j2ee.internal.web.operations.AddWebClassOperation.doExecute(AddWebClassOperation.java:67) at org.eclipse.jst.j2ee.internal.common.operations.AddJavaEEArtifactOperation$1.run(AddJavaEEArtifactOperation.java:47) at org.eclipse.jst.jee.model.internal.JEE5ModelProvider.modify(JEE5ModelProvider.java:249) at org.eclipse.jst.jee.model.internal.Web25MergedModelProvider.modify(Web25MergedModelProvider.java:76) at org.eclipse.jst.j2ee.internal.common.operations.AddJavaEEArtifactOperation.execute(AddJavaEEArtifactOperation.java:53) at org.eclipse.wst.common.frameworks.internal.datamodel.DataModelPausibleOperationImpl$1.run(DataModelPausibleOperationImpl.java:376) at org.eclipse.core.internal.resources.Workspace.run(Workspace.java:1800) at org.eclipse.wst.common.frameworks.internal.datamodel.DataModelPausibleOperationImpl.runOperation(DataModelPausibleOperationImpl.java:401) at org.eclipse.wst.common.frameworks.internal.datamodel.DataModelPausibleOperationImpl.runOperation(DataModelPausibleOperationImpl.java:352) at org.eclipse.wst.common.frameworks.internal.datamodel.DataModelPausibleOperationImpl.doExecute(DataModelPausibleOperationImpl.java:242) at org.eclipse.wst.common.frameworks.internal.datamodel.DataModelPausibleOperationImpl.executeImpl(DataModelPausibleOperationImpl.java:214) at org.eclipse.wst.common.frameworks.internal.datamodel.DataModelPausibleOperationImpl.cacheThreadAndContinue(DataModelPausibleOperationImpl.java:89) at org.eclipse.wst.common.frameworks.internal.datamodel.DataModelPausibleOperationImpl.execute(DataModelPausibleOperationImpl.java:202) at org.eclipse.wst.common.frameworks.internal.datamodel.ui.DataModelWizard$1$CatchThrowableRunnableWithProgress.run(DataModelWizard.java:219) at org.eclipse.jface.operation.ModalContext.runInCurrentThread(ModalContext.java:464) at org.eclipse.jface.operation.ModalContext.run(ModalContext.java:372) at org.eclipse.jface.wizard.WizardDialog.run(WizardDialog.java:934) at org.eclipse.wst.common.frameworks.internal.datamodel.ui.DataModelWizard.runOperations(DataModelWizard.java:228) at org.eclipse.wst.common.frameworks.internal.datamodel.ui.DataModelWizard.performFinish(DataModelWizard.java:186) at org.eclipse.jface.wizard.WizardDialog.finishPressed(WizardDialog.java:742) at org.eclipse.jface.wizard.WizardDialog.buttonPressed(WizardDialog.java:373) at org.eclipse.jface.dialogs.Dialog$2.widgetSelected(Dialog.java:624) at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:228) at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1003) at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3823) at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3422) at org.eclipse.jface.window.Window.runEventLoop(Window.java:825) at org.eclipse.jface.window.Window.open(Window.java:801) at org.eclipse.ui.internal.handlers.WizardHandler$New.executeHandler(WizardHandler.java:253) at org.eclipse.ui.internal.handlers.WizardHandler.execute(WizardHandler.java:273) at org.eclipse.ui.internal.handlers.HandlerProxy.execute(HandlerProxy.java:281) at org.eclipse.core.commands.Command.executeWithChecks(Command.java:476) at org.eclipse.core.commands.ParameterizedCommand.executeWithChecks(ParameterizedCommand.java:508) at org.eclipse.ui.internal.handlers.HandlerService.executeCommand(HandlerService.java:169) at org.eclipse.ui.internal.handlers.SlaveHandlerService.executeCommand(SlaveHandlerService.java:247) at org.eclipse.ui.internal.actions.CommandAction.runWithEvent(CommandAction.java:157) at org.eclipse.jface.action.ActionContributionItem.handleWidgetSelection(ActionContributionItem.java:583) at org.eclipse.jface.action.ActionContributionItem.access$2(ActionContributionItem.java:500) at org.eclipse.jface.action.ActionContributionItem$5.handleEvent(ActionContributionItem.java:411) at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1003) at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3823) at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3422) at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2384) at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2348) at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2200) at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:495) at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:288) at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:490) at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149) at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:113) at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:193) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:386) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179) 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:585) at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:549) at org.eclipse.equinox.launcher.Main.basicRun(Main.java:504) at org.eclipse.equinox.launcher.Main.run(Main.java:1236)不知道哪里出错了，请各位高手帮忙，谢谢了。