AppEngine错误
我正在寻找这个问题的解决scheme，但似乎很难。 我有一个处理注册的servlet的appengine项目。 当我尝试调用这个servlet时，我有这个日志报告：
012-04-19 10:31:06.816 /register 500 90ms 0kb Apache-HttpClient/UNAVAILABLE (java 1.4) ip - gecodroidtest [19/Apr/2012:10:31:06 -0700] "POST /register HTTP/1.1" 500 0 - "Apache-HttpClient/UNAVAILABLE (java 1.4)" "cloudnotifyit.appspot.com" ms=90 cpu_ms=58 api_cpu_ms=0 cpm_usd=0.001738 instance=00c61b117c772731eb45290bfcb07750c0505f W 2012-04-19 10:31:06.794 com.cloudnotify.server.servlet.RequestInfo processRequest: xxxxxxxxxxxx@xxxx //just for me W 2012-04-19 10:31:06.810 Error for /register java.lang.NoClassDefFoundError: org/w3c/dom/ElementTraversal at com.google.appengine.runtime.Request.process-240c2ffe1bf8ddba(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.apache.xerces.parsers.AbstractDOMParser.startDocument(Unknown Source) at org.apache.xerces.impl.dtd.XMLDTDValidator.startDocument(Unknown Source) at org.apache.xerces.impl.XMLDocumentScannerImpl.startEntity(Unknown Source) at org.apache.xerces.impl.XMLVersionDetector.startDocumentParsing(Unknown Source) at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source) at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source) at org.apache.xerces.parsers.XMLParser.parse(Unknown Source) at org.apache.xerces.parsers.DOMParser.parse(Unknown Source) at org.apache.xerces.jaxp.DocumentBuilderImpl.parse(Unknown Source) at javax.xml.parsers.DocumentBuilder.parse(DocumentBuilder.java:121) at javax.jdo.JDOHelper.readNamedPMFProperties(JDOHelper.java:1407) at javax.jdo.JDOHelper.getNamedPMFProperties(JDOHelper.java:1286) at javax.jdo.JDOHelper.getPropertiesFromJdoconfig(JDOHelper.java:1232) at javax.jdo.JDOHelper.getPersistenceManagerFactory(JDOHelper.java:1079) at javax.jdo.JDOHelper.getPersistenceManagerFactory(JDOHelper.java:914) at com.cloudnotify.server.c2dm.C2DMessaging.getPMF(C2DMessaging.java:103) at com.cloudnotify.server.servlet.RequestInfo.initDevices(RequestInfo.java:225) at com.cloudnotify.server.servlet.RequestInfo.processRequest(RequestInfo.java:183) at com.cloudnotify.server.servlet.RegisterServlet.doPost(RegisterServlet.java:100) 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$CachedChain.doFilter(ServletHandler.java:1166) at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) at org.mortbay.jetty.servlet.ServletHandler$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 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$RequestHandler.headerComplete(HttpConnection.java:923) at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404) at com.google.tracing.TraceContext$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) Caused by: java.lang.ClassNotFoundException: org.w3c.dom.ElementTraversal at com.google.appengine.runtime.Request.process-240c2ffe1bf8ddba(Request.java) ... 44 more C 2012-04-19 10:31:06.812 Uncaught exception from servlet java.lang.NoClassDefFoundError: org/w3c/dom/ElementTraversal at com.google.appengine.runtime.Request.process-240c2ffe1bf8ddba(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.apache.xerces.parsers.AbstractDOMParser.startDocument(Unknown Source) at org.apache.xerces.impl.dtd.XMLDTDValidator.startDocument(Unknown Source) at org.apache.xerces.impl.XMLDocumentScannerImpl.startEntity(Unknown Source) at org.apache.xerces.impl.XMLVersionDetector.startDocumentParsing(Unknown Source) at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source) at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source) at org.apache.xerces.parsers.XMLParser.parse(Unknown Source) at org.apache.xerces.parsers.DOMParser.parse(Unknown Source) at org.apache.xerces.jaxp.DocumentBuilderImpl.parse(Unknown Source) at javax.xml.parsers.DocumentBuilder.parse(DocumentBuilder.java:121) at javax.jdo.JDOHelper.readNamedPMFProperties(JDOHelper.java:1407) at javax.jdo.JDOHelper.getNamedPMFProperties(JDOHelper.java:1286) at javax.jdo.JDOHelper.getPropertiesFromJdoconfig(JDOHelper.java:1232) at javax.jdo.JDOHelper.getPersistenceManagerFactory(JDOHelper.java:1079) at javax.jdo.JDOHelper.getPersistenceManagerFactory(JDOHelper.java:914) at com.cloudnotify.server.c2dm.C2DMessaging.getPMF(C2DMessaging.java:103) at com.cloudnotify.server.servlet.RequestInfo.initDevices(RequestInfo.java:225) at com.cloudnotify.server.servlet.RequestInfo.processRequest(RequestInfo.java:183) at com.cloudnotify.server.servlet.RegisterServlet.doPost(RegisterServlet.java:100) 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$CachedChain.doFilter(ServletHandler.java:1166) at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) at org.mortbay.jetty.servlet.ServletHandler$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 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$RequestHandler.headerComplete(HttpConnection.java:923) at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404) at com.google.tracing.TraceContext$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) Caused by: java.lang.ClassNotFoundException: org.w3c.dom.ElementTraversal at com.google.appengine.runtime.Request.process-240c2ffe1bf8ddba(Request.java) ... 44 more Thanks all GAE上的Xercesparsing器可能存在一些问题。 请参阅http://code.google.com/p/googleappengine/issues/detail?id=1367
也许解决方法是确保所有的Xerces jar（包括xml-apis.jar）都在你的WEB-INF / lib目录下。
- MAVEN解决scheme：
在pom.xml中，将“xml-apis”依赖项设置为版本1.4.01：
<dependency> <groupId>xml-apis</groupId> <artifactId>xml-apis</artifactId> <version>1.4.01</version> </dependency>
- 针对每个人的解决scheme：
如果不使用maven，则可以手动添加xml-apis库（版本1.4.01）。 您将在xml-commons二进制包中find名为“XML Commons External 1.4.01”的jar文件，您可以在这里下载它： http : //xerces.apache.org/mirrors.cgi 。
最后，用这个版本的库编译和执行你的java应用程序/项目。
- 说明：
xml-apis库的1.4.01版本包含必需的ElementTraversal类。 其他版本如2.0.0,1.0.0等不包括它，并且在编译时应用程序失败。
您的问题可以通过更新到版本2.11.0.SP5来解决，该版本已经包含了类ElementTraversal 。
