在參閱 湯老師 著作 "雲端網頁程式設計：Google App Engine應用實作"
訪問湯老師 的 GAE 網址 http://guestbook995.appspot.com，老師的網站也是正常運作

學生實作第十章以 GWT 設計留言板，在本機 Run As -> Web Application 皆正常運作
並 Deploy 到 GAE http://shine8guestbook.appspot.com，在建立 RPC 時出現錯誤。查看 GAE Log 時得知下列錯誤訊息，期待艾鍗資訊老師或前輩指教！

學生的開發環境如下：
Eclipse Indigo
Java SDK 1.7.09
GWT SDK 2.4.0
GAE SDK 1.7.3

錯誤訊息：
220.135.38.251 - - [25/Oct/2012:19:07:55 -0700] "POST /guestbook/post HTTP/1.1" 500 0 "http://shine8guestbook.appspot.com/" "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0)" "shine8guestbook.appspot.com" ms=3384 cpu_ms=952 loading_request=1 instance=00c61b117cc4f08ecb50dfe8270b1f4b9aa04abe

W 2012-10-26 10:07:55.027

Failed startup of context com.google.apphosting.utils.jetty.RuntimeAppEngineWebAppContext@54824{/,/base/data/home/apps/s~shine8guestbook/1.362714592751119035}
org.mortbay.util.MultiException[java.lang.UnsupportedClassVersionError: com/guestbook/server/GreetingServiceImpl : Unsupported major.minor version 51.0, java.lang.UnsupportedClassVersionError: com/guestbook/server/PostServiceImpl : Unsupported major.minor version 51.0]
    at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:656)
    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$RequestRunnable.run(JavaRuntime.java:447)
    at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:454)
    at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:461)
    at com.google.tracing.TraceContext.runInContext(TraceContext.java:703)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:338)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:330)
    at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:458)
    at com.google.apphosting.runtime.ThreadGroupPool$PoolEntry.run(ThreadGroupPool.java:251)
    at java.lang.Thread.run(Thread.java:679)
java.lang.UnsupportedClassVersionError: com/guestbook/server/GreetingServiceImpl : Unsupported major.minor version 51.0
    at com.google.appengine.runtime.Request.process-28bbb726bf449033(Request.java)
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:634)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:277)
    at sun.reflect.GeneratedMethodAccessor5.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:616)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
    at org.mortbay.util.Loader.loadClass(Loader.java:91)
    at org.mortbay.util.Loader.loadClass(Loader.java:71)
    at org.mortbay.jetty.servlet.Holder.doStart(Holder.java:73)
    at org.mortbay.jetty.servlet.ServletHolder.doStart(ServletHolder.java:242)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:685)
    at org.mortbay.jetty.servlet.Context.startContext(Context.java:140)
    at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1250)
    at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:517)
    at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:467)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:454)
    at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:461)
    at com.google.tracing.TraceContext.runInContext(TraceContext.java:703)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:338)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:330)
    at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:458)
    at java.lang.Thread.run(Thread.java:679)
java.lang.UnsupportedClassVersionError: com/guestbook/server/PostServiceImpl : Unsupported major.minor version 51.0
    at com.google.appengine.runtime.Request.process-28bbb726bf449033(Request.java)
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:634)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:277)
    at sun.reflect.GeneratedMethodAccessor5.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:616)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
    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$TraceContextRunnable.runInContext(TraceContext.java:454)
    at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:461)
    at com.google.tracing.TraceContext.runInContext(TraceContext.java:703)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:338)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:330)
    at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:458)
    at java.lang.Thread.run(Thread.java:679)

C 2012-10-26 10:07:55.032

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$RequestRunnable.run(JavaRuntime.java:447)
    at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:454)
    at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:461)
    at com.google.tracing.TraceContext.runInContext(TraceContext.java:703)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:338)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:330)
    at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:458)
    at com.google.apphosting.runtime.ThreadGroupPool$PoolEntry.run(ThreadGroupPool.java:251)
    at java.lang.Thread.run(Thread.java:679)

I 2012-10-26 10:07:55.045

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.