最近在学习中，发现一个问题，如果使用eclipse自带的server，Run on Server将项目部署到tomcat服务器是是没有错误的，但是使用Tomcat插件，Tomcat Project→Update context definition后，出现了以下错误：
严重: End event threw exception java.lang.NoSuchMethodException: org.apache.catalina.deploy.WebXml addServlet at org.apache.tomcat.util.IntrospectionUtils.callMethod1(IntrospectionUtils.java:849) at org.apache.tomcat.util.digester.SetNextRule.end(SetNextRule.java:201) at org.apache.tomcat.util.digester.Digester.endElement(Digester.java:1060) at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.endElement(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanEndElement(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(Unknown Source) at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source) at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source) at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source) at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(Unknown Source) at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(Unknown Source) at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(Unknown Source) at org.apache.tomcat.util.digester.Digester.parse(Digester.java:1555) at org.apache.catalina.startup.ContextConfig.parseWebXml(ContextConfig.java:1856) at org.apache.catalina.startup.ContextConfig.getDefaultWebXmlFragment(ContextConfig.java:1494) at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1255) at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:887) at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:387) at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:117) at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90) at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5472) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147) at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:899) at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:875) at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:652) at org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:679) at org.apache.catalina.startup.HostConfig$DeployDescriptor.run(HostConfig.java:1966) at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) at java.util.concurrent.FutureTask.run(Unknown Source) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.lang.Thread.run(Unknown Source)
并且启动后主页和项目都会显示404,。
这里需要将tomcat文件路径下conf→context.xml进行修改，添加<Loader delegate="true"/>即可解决这个问题：
<Context> <!-- Default set of monitored resources --> <WatchedResource>WEB-INF/web.xml</WatchedResource> <Loader delegate="true"/> <!-- Uncomment this to disable session persistence across Tomcat restarts --> <!-- <Manager pathname="" /> --> <!-- Uncomment this to enable Comet connection tacking (provides events on session expiration as well as webapp lifecycle) --> <!-- <Valve className="org.apache.catalina.valves.CometConnectionManagerValve" /> --> </Context>
