GAE - 部署到Appspot服务器后的ClassNotFoundException

Question

我已经使用Maven的原型com.google.appengine.archetypes:guestbook-archetype创建了Google的示例留言簿项目。当我使用mvn appengine:devserver在本地运行它时工作正常，当我尝试在Google的Appspot上部署问题时，问题就出现了。我收到以下消息：

Error: Server Error

The server encountered an error and could not complete your request.
If the problem persists, please report your problem and mention this error message and the query that caused it.

在日志中我可以看到：

2013-05-01 05:38:28.356 / 500 3166ms 0kb Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.31 (KHTML, like Gecko) Chrome/26.0.1410.63 Safari/537.31
2001:6d8:10:a014:5176:bdbe:c152:53c0 - - [01/May/2013:05:38:28 -0700] "GET / HTTP/1.1" 500 0 - "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.31 (KHTML, like Gecko) Chrome/26.0.1410.63 Safari/537.31" "aghinzop.appspot.com" ms=3167 cpu_ms=2100 loading_request=1 app_engine_release=1.7.7 instance=00c61b117cdf51947e909cbfaf52e1739a7f4c
W 2013-05-01 05:38:28.325
EXCEPTION 
java.lang.ClassNotFoundException: ioserv.ioserv.SignGuestbookServlet
    at com.google.appengine.runtime.Request.process-53e8711216f37199(Request.java)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:359)
    at org.mortbay.util.Loader.loadClass(Loader.java:91)
    at org.mortbay.util.Loader.loadClass(Loader.java:71)
    at org.mortbay.jetty.servlet.Holder.doStart(Holder.java:73)
    at org.mortbay.jetty.servlet.ServletHolder.doStart(ServletHolder.java:242)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:685)
    at org.mortbay.jetty.servlet.Context.startContext(Context.java:140)
    at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1250)
    at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:517)
    at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:467)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:480)
    at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:487)
    at com.google.tracing.TraceContext.runInContext(TraceContext.java:774)
    at com.google.tracing.TraceContext$DoInTraceContext.runInContext(TraceContext.java:751)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:342)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:334)
    at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:484)
    at java.lang.Thread.run(Thread.java:722)
E 2013-05-01 05:38:28.326
javax.servlet.ServletContext log: unavailable
javax.servlet.UnavailableException: ioserv.ioserv.SignGuestbookServlet
    at org.mortbay.jetty.servlet.Holder.doStart(Holder.java:79)
    at org.mortbay.jetty.servlet.ServletHolder.doStart(ServletHolder.java:242)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:685)
    at org.mortbay.jetty.servlet.Context.startContext(Context.java:140)
    at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1250)
    at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:517)
    at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:467)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.createHandler(AppVersionHandlerMap.java:219)
    at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.getHandler(AppVersionHandlerMap.java:194)
    at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:134)
    at com.google.apphosting.runtime.JavaRuntime$RequestRunnable.run(JavaRuntime.java:438)
    at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:480)
    at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:487)
    at com.google.tracing.TraceContext.runInContext(TraceContext.java:774)
    at com.google.tracing.TraceContext$DoInTraceContext.runInContext(TraceContext.java:751)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:342)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:334)
    at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:484)
    at com.google.apphosting.runtime.ThreadGroupPool$PoolEntry.run(ThreadGroupPool.java:251)
    at java.lang.Thread.run(Thread.java:722)
W 2013-05-01 05:38:28.338
Failed startup of context com.google.apphosting.utils.jetty.RuntimeAppEngineWebAppContext@11c3e97{/,/base/data/home/apps/s~aghinzop/1.367061823227494749}
java.lang.NullPointerException
    at java.lang.Class.isAssignableFrom(Native Method)
    at org.mortbay.jetty.servlet.ServletHolder.doStart(ServletHolder.java:256)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:685)
    at org.mortbay.jetty.servlet.Context.startContext(Context.java:140)
    at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1250)
    at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:517)
    at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:467)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.createHandler(AppVersionHandlerMap.java:219)
    at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.getHandler(AppVersionHandlerMap.java:194)
    at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:134)
    at com.google.apphosting.runtime.JavaRuntime$RequestRunnable.run(JavaRuntime.java:438)
    at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:480)
    at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:487)
    at com.google.tracing.TraceContext.runInContext(TraceContext.java:774)
    at com.google.tracing.TraceContext$DoInTraceContext.runInContext(TraceContext.java:751)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:342)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:334)
    at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:484)
    at com.google.apphosting.runtime.ThreadGroupPool$PoolEntry.run(ThreadGroupPool.java:251)
    at java.lang.Thread.run(Thread.java:722)
C 2013-05-01 05:38:28.342
Uncaught exception from servlet
javax.servlet.UnavailableException: Initialization failed.
    at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.createHandler(AppVersionHandlerMap.java:228)
    at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.getHandler(AppVersionHandlerMap.java:194)
    at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:134)
    at com.google.apphosting.runtime.JavaRuntime$RequestRunnable.run(JavaRuntime.java:438)
    at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:480)
    at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:487)
    at com.google.tracing.TraceContext.runInContext(TraceContext.java:774)
    at com.google.tracing.TraceContext$DoInTraceContext.runInContext(TraceContext.java:751)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:342)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:334)
    at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:484)
    at com.google.apphosting.runtime.ThreadGroupPool$PoolEntry.run(ThreadGroupPool.java:251)
    at java.lang.Thread.run(Thread.java:722)
I 2013-05-01 05:38:28.355
This request caused a new process to be started for your application, and thus caused your application code to be loaded for the first time. This request may thus take longer and use more CPU than a typical request for your application.

以下是我在Eclipse和部署日志中使用的基本设置（我使用App Engine Eclipse插件）。

我不确定“禁用，因为这是一个Maven项目”在这里意味着什么。你能解释一下吗？我应该看看这个方框吗？

此处选择的App Engine SDK是Eclipse插件提供的。

以下是插件提供的库。原型中还添加了一些Maven库。

这是WEB-INF / lib中的lib。我可以看到它们很少，我意识到可能缺少某些东西。问题是当我尝试将libs复制到这个文件夹时，我得到Cannot paste the clipboard contents into the selected elements。我怎样才能做到这一点？在正常的动态Web项目中（使用此方面），它就像Properties>Deployment Assembly>Add一样简单，但在这里我不知道如何做到这一点。

我真的很感谢你的帮助！谢谢！

Answer 1

  

我不确定“禁用，因为这是一个Maven项目”在这里意味着什么。你能解释一下吗？我应该看看这个方框吗？

有两种方法可以管理你的应用程序（特别是web文件夹），一种让maven做，另一种是google eclipse插件。由于您的应用程序是由maven构建的，因此默认假设您的Web应用程序管理由maven本身完成，因此google eclipse插件默认禁用它。  除非你不删除maven，否则它应该是原样。

出现错误，我的猜测是，虽然您正在构建和测试maven，但您可能正在尝试通过eclipse进行部署，请尝试使用mvn appengine：update并且它应该可以正常工作。

希望它有所帮助。