过去几天我一直在寻找这个问题的解决方案，没有找到解决方案的运气。 我在Eclipse中有一个GAE应用程序，我正在尝试使用Tiles。我将Tiles jar放在WEB-INF / lib /目录中，并将它们全部添加到Java Build Path中。
目前这是我的web.xml。
<?xml version="1.0" encoding="utf-8" standalone="no"?><web-app xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.5" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<servlet>
<servlet-name>SystemServiceServlet</servlet-name>
<servlet-class>com.google.api.server.spi.SystemServiceServlet</servlet-class>
<init-param>
<param-name>services</param-name>
<param-value/>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>SystemServiceServlet</servlet-name>
<url-pattern>/_ah/spi/*</url-pattern>
</servlet-mapping>
<listener>
<listener-class>org.apache.tiles.extras.complete.CompleteAutoloadTilesListener</listener-class>
</listener>
<servlet>
<servlet-name>Tiles Dispatch Servlet</servlet-name>
<servlet-class>org.apache.tiles.web.util.TilesDispatchServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Tiles Dispatch Servlet</servlet-name>
<url-pattern>*.tiles</url-pattern>
</servlet-mapping>
</web-app>
但是，当我尝试运行该应用程序时，收到以下消息：
2012-10-12 20:10:42.057 java[33932:707] [Java CocoaComponent compatibility mode]: Enabled
2012-10-12 20:10:42.058 java[33932:707] [Java CocoaComponent compatibility mode]: Setting timeout for SWT to 0.100000
Oct 13, 2012 12:10:43 AM com.google.apphosting.utils.jetty.JettyLogger info
INFO: Logging to JettyLogger(null) via com.google.apphosting.utils.jetty.JettyLogger
Oct 13, 2012 12:10:43 AM com.google.apphosting.utils.config.AppEngineWebXmlReader readAppEngineWebXml
INFO: Successfully processed /Users/nblue/Workspaces/Eclipse/WhatsOnBB/war/WEB-INF/appengine-web.xml
Oct 13, 2012 12:10:43 AM com.google.apphosting.utils.config.AbstractConfigXmlReader readConfigXml
INFO: Successfully processed /Users/nblue/Workspaces/Eclipse/WhatsOnBB/war/WEB-INF/web.xml
Oct 13, 2012 12:10:45 AM com.google.apphosting.utils.jetty.JettyLogger warn
WARNING: Failed startup of context com.google.appengine.tools.development.DevAppEngineWebAppContext@7041a12f{/,/Users/nblue/Workspaces/Eclipse/WhatsOnBB/war}
java.lang.NullPointerException
at org.apache.tiles.el.JspExpressionFactoryFactory.getExpressionFactory(JspExpressionFactoryFactory.java:61)
at org.apache.tiles.extras.complete.CompleteAutoloadTilesContainerFactory.createELEvaluator(CompleteAutoloadTilesContainerFactory.java:242)
at org.apache.tiles.extras.complete.CompleteAutoloadTilesContainerFactory.createAttributeEvaluatorFactory(CompleteAutoloadTilesContainerFactory.java:182)
at org.apache.tiles.factory.BasicTilesContainerFactory.createContainer(BasicTilesContainerFactory.java:88)
at org.apache.tiles.startup.AbstractTilesInitializer.createContainer(AbstractTilesInitializer.java:114)
at org.apache.tiles.startup.AbstractTilesInitializer.initialize(AbstractTilesInitializer.java:64)
at org.apache.tiles.web.startup.AbstractTilesListener.contextInitialized(AbstractTilesListener.java:53)
at org.mortbay.jetty.handler.ContextHandler.startContext(ContextHandler.java:548)
at org.mortbay.jetty.servlet.Context.startContext(Context.java:136)
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 org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:130)
at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:130)
at org.mortbay.jetty.Server.doStart(Server.java:224)
at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
at com.google.appengine.tools.development.JettyContainerService.startContainer(JettyContainerService.java:202)
at com.google.appengine.tools.development.AbstractContainerService.startup(AbstractContainerService.java:248)
at com.google.appengine.tools.development.DevAppServerImpl.start(DevAppServerImpl.java:157)
at com.google.appengine.tools.development.DevAppServerMain$StartAction.apply(DevAppServerMain.java:333)
at com.google.appengine.tools.util.Parser$ParseResult.applyArgs(Parser.java:48)
at com.google.appengine.tools.development.DevAppServerMain.<init>(DevAppServerMain.java:269)
at com.google.appengine.tools.development.DevAppServerMain.main(DevAppServerMain.java:245)
Oct 13, 2012 12:10:45 AM com.google.appengine.tools.development.DevAppServerImpl start
INFO: The server is running at http://localhost:8888/
Oct 13, 2012 12:10:45 AM com.google.appengine.tools.development.DevAppServerImpl start
INFO: The admin console is running at http://localhost:8888/_ah/admin
我见过类似的消息，但没有一个完全匹配。我删除了其他servlet的web.xml以查看它们是否导致了问题，但得到了相同的结果。有什么建议吗？