Google app engine java.io.NotSerializableException:com.opensymphony.xwork2.inject.ContainerImpl$ConstructorInjector

我正在谷歌应用程序引擎上使用Struts2。在我的本地开发框中，应用程序运行良好。但是 上传到谷歌的云，我得到以下例外

我正在使用以下二进制文件

struts2.3.1.2（&依赖jar文件） xwork-core-2.3.1.2
GAE SDK发行版：1.6.6

    java.lang.RuntimeException: java.io.NotSerializableException: com.opensymphony.xwork2.inject.ContainerImpl$ConstructorInjector
        at com.google.apphosting.runtime.jetty.SessionManager.serialize(SessionManager.java:373)
        at com.google.apphosting.runtime.jetty.DatastoreSessionStore.createEntityForSession(DatastoreSessionStore.java:71)
        at com.google.apphosting.runtime.jetty.DatastoreSessionStore.saveSession(DatastoreSessionStore.java:93)
        at com.google.apphosting.runtime.jetty.SessionManager$AppEngineSession.save(SessionManager.java:164)
        at com.google.apphosting.runtime.jetty.SaveSessionFilter.doFilter(SaveSessionFilter.java:41)
        at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
        at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43)
        at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
        at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
        at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
        at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
        at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
        at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
        at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.handle(AppVersionHandlerMap.java:249)
        at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
        at org.mortbay.jetty.Server.handle(Server.java:326)
        at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
        at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:923)
        at com.google.apphosting.runtime.jetty.RpcRequestParser.parseAvailable(RpcRequestParser.java:76)
        at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
        at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:135)
        at com.google.apphosting.runtime.JavaRuntime$RequestRunnable.run(JavaRuntime.java:477)
        at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:449)
        at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:455)
        at com.google.tracing.TraceContext.runInContext(TraceContext.java:695)
        at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:333)
        at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:325)
        at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:453)
        at com.google.apphosting.runtime.ThreadGroupPool$PoolEntry.run(ThreadGroupPool.java:251)
        at java.lang.Thread.run(Thread.java:679)

我甚至尝试过最新版本的XWorkCoreAPI，但没有任何收获。 我在这个网站上看到过这类问题的报道，但没有令人满意的解决方案或答案。 有人能帮我解决这个问题吗

如果在Action类中使用ArrayList是这个类的根类，那么作为一种解决方法，我应该选择ArrayList的替代方法吗？建议使用哪一种

-谢谢 妈