今天启动tomcat服务器就报出来以下异常，百度了一下，有人说是jdk版本和tomcat的版本不兼容，但我感觉不是，我将tomcat目录下的项目删除后就回复正常了，从抛出的异常来看是不是web.xml文档有问题
java.lang.reflect.InvocationTargetException
at sun.reflect.GeneratedMethodAccessor18.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.apache.tomcat.util.IntrospectionUtils.callMethodN(IntrospectionUtils.java:905)
at org.apache.catalina.startup.CallMethodMultiRule.end(WebRuleSet.java:1021)
at org.apache.tomcat.util.digester.Digester.endElement(Digester.java:1060)
at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.endElement(AbstractSAXParser.java:609)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanEndElement(XMLDocumentFragmentScannerImpl.java:1783)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(XMLDocumentFragmentScannerImpl.java:2970)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:606)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:510)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:848)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:777)
at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:141)
at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1213)
at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:643)
at org.apache.tomcat.util.digester.Digester.parse(Digester.java:1555)
at org.apache.catalina.startup.ContextConfig.parseWebXml(ContextConfig.java:1843)
at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1263)
at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:889)
at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:386)
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:5405)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:901)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:652)
at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1263)
at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:1948)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)Caused by: java.lang.IllegalArgumentException: The servlets named [Kenan] and [Kenan] are both mapped to the url-pattern [] which is not permitted
at org.apache.catalina.deploy.WebXml.addServletMapping(WebXml.java:293)
... 35 more
三月 11, 2016 10:21:13 上午 org.apache.catalina.startup.ContextConfig parseWebXml
严重: Parse error in application web.xml file at jndi:/localhost/Web/WEB-INF/web.xml
org.xml.sax.SAXParseException; systemId: jndi:/localhost/Web/WEB-INF/web.xml; lineNumber: 20; columnNumber: 21; Error at (20, 21) : The servlets named [Kenan] and [Kenan] are both mapped to the url-pattern [] which is not permitted
at org.apache.tomcat.util.digester.Digester.createSAXException(Digester.java:2705)
at org.apache.tomcat.util.digester.Digester.createSAXException(Digester.java:2737)
at org.apache.tomcat.util.digester.Digester.endElement(Digester.java:1063)
at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.endElement(AbstractSAXParser.java:609)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanEndElement(XMLDocumentFragmentScannerImpl.java:1783)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(XMLDocumentFragmentScannerImpl.java:2970)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:606)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:510)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:848)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:777)
at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:141)
at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1213)
at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:643)
at org.apache.tomcat.util.digester.Digester.parse(Digester.java:1555)
at org.apache.catalina.startup.ContextConfig.parseWebXml(ContextConfig.java:1843)
at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1263)
at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:889)
at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:386)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:117)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5405)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:901)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:652)
at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1263)
at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:1948)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)Caused by: java.lang.IllegalArgumentException: The servlets named [Kenan] and [Kenan] are both mapped to the url-pattern [] which is not permitted
at org.apache.catalina.deploy.WebXml.addServletMapping(WebXml.java:293)
at sun.reflect.GeneratedMethodAccessor18.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.apache.tomcat.util.IntrospectionUtils.callMethodN(IntrospectionUtils.java:905)
at org.apache.catalina.startup.CallMethodMultiRule.end(WebRuleSet.java:1021)
at org.apache.tomcat.util.digester.Digester.endElement(Digester.java:1060)
... 29 more
三月 11, 2016 10:21:13 上午 org.apache.catalina.startup.ContextConfig parseWebXml
严重: Occurred at line 20 column 21
三月 11, 2016 10:21:13 上午 org.apache.catalina.startup.ContextConfig configureStart
严重: Marking this application unavailable due to previous error(s)
三月 11, 2016 10:21:13 上午 org.apache.catalina.startup.TldConfig execute
信息: At least one JAR was scanned for TLDs yet contained no TLDs. Enable debug logging for this logger for a complete list of JARs that were scanned but no TLDs were found in them. Skipping unneeded JARs during scanning can improve startup time and JSP compilation time.
三月 11, 2016 10:21:13 上午 org.apache.catalina.core.StandardContext startInternal
严重: One or more components marked the context as not correctly configured
三月 11, 2016 10:21:13 上午 org.apache.catalina.core.StandardContext startInternal
严重: Context [/Web] startup failed due to previous errors
三月 11, 2016 10:21:13 上午 org.apache.catalina.startup.HostConfig deployDirectory
信息: Deployment of web application directory E:\tomkat\apache-tomcat-7.0.64\webapps\Web has finished in 263 ms
三月 11, 2016 10:21:13 上午 org.apache.coyote.AbstractProtocol start
信息: Starting ProtocolHandler ["http-apr-8080"]
三月 11, 2016 10:21:14 上午 org.apache.coyote.AbstractProtocol start
信息: Starting ProtocolHandler ["ajp-apr-8009"]
三月 11, 2016 10:21:14 上午 org.apache.catalina.startup.Catalina start
信息: Server startup in 7649 ms
systemId: jndi:/localhost/Web/WEB-INF/web.xml; lineNumber: 20; columnNumber: 21; Error at (20, 21) : The servlets named [Kenan] and [Kenan] are both mapped to the url-pattern [] which is not permitted
一个提示很明显了，你有两个同名的servlet kenan，其中一个改名就对了