我正在研究gwt2.4，jre7和GAE 1.7.3.in开发模式我的代码工作正常，但是当我在app引擎上传我的应用程序时，我得到的跟踪错误
java.lang.ExceptionInInitializerError
at com.amazonaws.services.s3.AmazonS3Client.<init>(AmazonS3Client.java:277)
at com.wa.gwtamazon.server.UploadServiceImpl.amazonConfig(UploadServiceImpl.java:124)
at com.wa.gwtamazon.server.UploadServiceImpl.doPost(UploadServiceImpl.java:76)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
at com.google.apphosting.utils.servlet.ParseBlobUploadFilter.doFilter(ParseBlobUploadFilter.java:100)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.apphosting.runtime.jetty.SaveSessionFilter.doFilter(SaveSessionFilter.java:35)
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:266)
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$RequestHandler.headerComplete(HttpConnection.java:923)
at com.google.apphosting.runtime.jetty.RpcRequestParser.parseAvailable(RpcRequestParser.java:76)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:146)
at com.google.apphosting.runtime.JavaRuntime$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$PoolEntry.run(ThreadGroupPool.java:251)
at java.lang.Thread.run(Thread.java:679)
Nested in java.lang.ExceptionInInitializerError:
java.lang.NullPointerException
at com.amazonaws.util.VersionInfoUtils.initializeUserAgent(VersionInfoUtils.java:124)
at com.amazonaws.util.VersionInfoUtils.getUserAgent(VersionInfoUtils.java:86)
at com.amazonaws.ClientConfiguration.<clinit>(ClientConfiguration.java:31)
at com.amazonaws.services.s3.AmazonS3Client.<init>(AmazonS3Client.java:277)
at com.wa.gwtamazon.server.AmazonService.uploadFileToAmazone(AmazonService.java:50)
at com.wa.gwtamazon.server.AmazonService.doPost(AmazonService.java:36)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
at com.google.apphosting.utils.servlet.ParseBlobUploadFilter.doFilter(ParseBlobUploadFilter.java:100)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.apphosting.runtime.jetty.SaveSessionFilter.doFilter(SaveSessionFilter.java:35)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.handle(AppVersionHandlerMap.java:266)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:326)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
at org.mortbay.jetty.HttpConnection$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:146)
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)
我也在以下链接中找到解决方案，但仍然无法正常工作
（http://code.google.com/p/googleappengine/issues/detail?id=8166）
答案 0 :(得分：3)
//编辑：他将以下XML添加到appengine-web.xml以使其正常工作：
<system-properties>
<property name="java.util.logging.config.file" value="WEB-INF/logging.properties"/>
<property name="os.name" value="Linux" />
<property name="os.version" value="6.1" />
<property name="java.vm.name" value="Java HotSpot(TM) Client VM" />
<property name="java.vm.version" value="23.5-b02" />
<property name="user.language" value="en" />
<property name="user.region" value="us" />
</system-properties>
由于Google App Engine中的限制（无线程，...），您无法使用Amazon Libs。 但是，很少有解决方案可以帮助您：
[1] http://socialappdev.com/using-amazon-s3-with-google-app-engine-02-2011
[2] https://github.com/handstandtech/s3-simple-appengine
为什么不将Google Cloud Storage与GAE Java SDK一起使用？ GCS API与S3 API几乎相同。
答案 1 :(得分：2)
有些时候app引擎没有获得os.name，os.version，java.vm.name等的值，所以我们必须在appengine-web.xml文件中手动指定
<system-properties>
<property name="os.name" value="Linux" />
<property name="os.version" value="6.1" />
<property name="java.vm.name" value="Java HotSpot(TM) Client VM" />
<property name="java.vm.version" value="23.5-b02" />
<property name="user.language" value="en" />
<property name="user.region" value="us" />