Eclipse使用Tomcat插件产生的java.lang.NoSuchMethodException: org.apache.catalina.deploy.WebXml addServlet问题

最近在学习中，发现一个问题，若是使用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，可是使用Tomcat插件，Tomcat Project→Update context definition后，出现了如下错误：

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)

而且启动后主页和项目都会显示404,。

这里须要将tomcat文件路径下conf→context.xml进行修改，添加<Loader delegate="true"/>便可解决这个问题：

<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>