部署GWT SQL實例到AppEngine上，獲得登錄DB

Question

錯誤最近，我跟着在谷歌雲SQL和GWT本教程：http://code.google.com/apis/sql/docs/developers_guide_java.html

我不必創建GuestbookExample.gwt後部署這個程序，我的谷歌雲的SQL Server .xml文件。我想，我創造了它正確：

<!-- Inherit the default GWT style sheet. You can change  --> 
    <!-- the theme of your GWT application by uncommenting   --> 
    <!-- any one of the following lines.       --> 
    <inherits name='com.google.gwt.user.theme.clean.Clean'/> 
    <!-- <inherits name='com.google.gwt.user.theme.standard.Standard'/> --> 
    <!-- <inherits name='com.google.gwt.user.theme.chrome.Chrome'/> --> 
    <!-- <inherits name='com.google.gwt.user.theme.dark.Dark'/>  --> 

    <!-- Other module inherits          --> 

    <!-- Specify the app entry point class.       --> 

    <!-- Specify the paths for translatable code     --> 
    <source path='guestbook'/> 

</module> 

它能夠部署到沒有從GWT編譯器編譯問題的服務器。

當我嘗試訪問鏈接到項目中，我得到了HTTP錯誤Appspot上網站：

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. 

我認爲這是奇怪的，所以我檢查日誌上DATABSE對谷歌Cloud SQL的，我看到了錯誤如下：

[02/Dec/2011:11:25:36 -0800] "GET/HTTP/1.1" 500 0 - "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:8.0) Gecko/20100101 Firefox/8.0" "cst433t1proj.appspot.com" ms=109 cpu_ms=175 api_cpu_ms=0 cpm_usd=0.004894 instance=00c61b117cb6def6096f8754a01131e49502 

C 2011-12-02 11:25:36.913 

Uncaught exception from servlet 
java.lang.UnsupportedClassVersionError: guestbook/GuestbookServlet : Unsupported major.minor version 51.0 
    at com.google.appengine.runtime.Request.process-0000000000000000(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$TraceContextRunnable.runInContext(TraceContext.java:449) 
    at com.google.tracing.TraceContext$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 java.lang.Thread.run(Thread.java:679) 

我該怎麼辦才能解決此錯誤？林在這個數據庫的東西。我剛剛學習GWT來協助創建最終項目。任何幫助，將不勝感激。

Answer 1

您可能正在使用Java 7？ GAE支持特定版本的Java檢查http://code.google.com/appengine/docs/java/overview.html並查看您是否使用不受支持的版本。