java - GAE - 部署到 Appspot 服务器后出现 ClassNotFoundException

Question

我已经使用 Maven 的原型(prototype) 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，它工作正常，但当我尝试将它部署到 Google 的 Appspot 上时，问题就开始了。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 中的基本设置和部署日志(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？我应该选中此框吗？

这里选择的App Engine SDK是Eclipse Plugin提供的。

这是插件提供的库。还有一些由原型(prototype)添加的 Maven 库。

这是 WEB-INF/lib 中的库。我可以看到它们的数量很少，并且我意识到可能缺少一些东西。问题是，当我尝试将库复制到此文件夹中时，我得到无法将剪贴板内容粘贴到所选元素。我怎样才能做到这一点？在普通的动态 Web 项目(使用此方面)中，它就像 Properties>Deployment Assembly>Add 一样简单，但在这里我不知道如何执行此操作。

非常感谢您的帮助!谢谢!

Answer 1

I'm not sure what "disabled because this is a Maven project" means here. Could you explain? And should I check this box?

有两种方法来管理您的应用程序(特别是 Web 文件夹)，一种让 Maven 来管理，另一种让 google eclipse 插件来管理。由于您的应用程序是由maven构建的，默认假设您的Web应用程序管理是由maven本身完成的，因此google eclipse插件默认情况下禁用了它。 除非你不删除maven，否则它应该是这样的。

出现错误，我的猜测是，虽然您正在通过 Maven 进行构建和测试，但您可能会尝试通过 Eclipse 进行部署，请尝试 mvn appengine:update ，它应该可以工作。

希望有帮助。