我最近从GWT 2.0.4更新到2.1.0版。自那以后，我无法再编译我的GWT应用程序。当我点击GWT Eclipse插件的GWT编译按钮时，会出现以下错误：
java.lang.NoClassDefFoundError: com/google/gwt/dev/Compiler
Caused by: java.lang.ClassNotFoundException: com.google.gwt.dev.Compiler
at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
Exception in thread "main"
我无法在Eclipse中创建新的GWT项目。在新的Web应用程序项目对话框中，可以选择使用GWT和/或Google App Engine。当选中“使用GWT”时，会弹出一个错误对话框，其中显示：“元素创建失败。原因：com.google.gwt.user.tools.WebAppCreator的调用失败。有关更多详细信息，请参见错误日志。”
在日志文件（
<workspace>/.metadata/.log）中，我可以看到以下消息：!ENTRY org.eclipse.jdt.ui 4 10001 2010-11-02 08:34:50.085
!MESSAGE Internal Error
!STACK 1
Java Model Exception: Core Exception [code 0] Invocation of com.google.gwt.user.tools.WebAppCreator failed. See the error log for more details.
at org.eclipse.jdt.internal.core.BatchOperation.executeOperation(BatchOperation.java:50)
at org.eclipse.jdt.internal.core.JavaModelOperation.run(JavaModelOperation.java:728)
at org.eclipse.core.internal.resources.Workspace.run(Workspace.java:1975)
at org.eclipse.jdt.core.JavaCore.run(JavaCore.java:4777)
at org.eclipse.jdt.internal.ui.actions.WorkbenchRunnableAdapter.run(WorkbenchRunnableAdapter.java:106)
at org.eclipse.jface.operation.ModalContext$ModalContextThread.run(ModalContext.java:121)
Caused by: org.eclipse.core.runtime.CoreException: Invocation of com.google.gwt.user.tools.WebAppCreator failed. See the error log for more details.
at com.google.gwt.eclipse.core.runtime.tools.WebAppProjectCreatorRunner.createProject(WebAppProjectCreatorRunner.java:53)
at com.google.gdt.eclipse.suite.wizards.WebAppProjectCreator.createGWTProject(WebAppProjectCreator.java:532)
at com.google.gdt.eclipse.suite.wizards.WebAppProjectCreator.create(WebAppProjectCreator.java:294)
at com.google.gdt.eclipse.suite.wizards.NewWebAppProjectWizard.finishPage(NewWebAppProjectWizard.java:147)
at org.eclipse.jdt.internal.ui.wizards.NewElementWizard$2.run(NewElementWizard.java:117)
at org.eclipse.jdt.internal.core.BatchOperation.executeOperation(BatchOperation.java:39)
at org.eclipse.jdt.internal.core.JavaModelOperation.run(JavaModelOperation.java:728)
at org.eclipse.core.internal.resources.Workspace.run(Workspace.java:1975)
at org.eclipse.jdt.core.JavaCore.run(JavaCore.java:4777)
at org.eclipse.jdt.internal.ui.actions.WorkbenchRunnableAdapter.run(WorkbenchRunnableAdapter.java:106)
at org.eclipse.jface.operation.ModalContext$ModalContextThread.run(ModalContext.java:121)
!SUBENTRY 1 com.google.gwt.eclipse.core 4 0 2010-11-02 08:34:50.085
!MESSAGE Invocation of com.google.gwt.user.tools.WebAppCreator failed. See the error log for more details.
有人有解决这个问题的想法吗？我还设置了一个全新的Eclipse安装，安装了新的GWT插件，并选择了一个新的工作区目录，但这仍然给我带来了错误...
附加信息：
- Windows XP
- Eclipse for Java EE 3.6 Helios
- J2EE / Java 1.6.0_22-b04
- Google Plugin for Eclipse 3.6 1.4.0.v201010280102
- Google App Engine Java SDK 1.3.8 1.3.8.v201010161055
- Google Web Toolkit SDK 2.1.0 2.1.0.v201010280102