出现Server Tomcat v7.0 Server at localhost failed to start的解决方法

故事由来：

　　学Servlet中，突然发现启动Tomcat时出现这个问题

故事梗概：

　　学习servlet尽然能碰到服务器起不来的，百思不得其解，然后我百度，我FQgoogle，找stackoverflow。找到了不少答案，比如stackoverflow给出说是在

1

<workspace-directory>\.metadata\.plugins\org.eclipse.core.resources

　　中有个.snap文件删掉，就可解决这个问题，我试了不行。stackoverflow的链接如下：http://stackoverflow.com/questions/13244233/server-tomcat-v7-0-server-at-localhost-failed-to-start-without-stack-trace-whi。

百度下，Myexception网给出答案是1、端口被占用，2、启动时间不够，3、eclipse引发的问题，4、重新启动电脑（最笨的办法，如果不停的出现，不停的重起会烦死的。）。下面是原文链接。这答案给的没有一个是我要的，所以，以后还是尽量谷歌，百度感觉真心不靠谱。

故事真相：

　　在eclipse这个强大的软件中，我们省略很多手动写代码的时间，过程如下：

 

在上图中点击finish后就生成下面的代码。

比如在eclipse中，我们建一个新的 servlet文件后，代码中会生成如下一大块代码。

import java.io.IOException; 2 import javax.servlet.ServletException; 3 import javax.servlet.annotation.WebServlet; 4 import javax.servlet.http.HttpServlet; 5 import javax.servlet.http.HttpServletRequest; 6 import javax.servlet.http.HttpServletResponse; 7  8 /** 9  * Servlet implementation class ServletDemo10  */11 @WebServlet("/ServletDemo")12 public class ServletDemo extends HttpServlet {13     private static final long serialVersionUID = 1L;14        15     /**16      * @see HttpServlet#HttpServlet()17      */18     public ServletDemo() {19         super();20         // TODO Auto-generated constructor stub21     }22 23     /**24      * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)25      */26     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {27         // TODO Auto-generated method stub28         response.getWriter().append("Served at: ").append(request.getContextPath());29     }30 31     /**32      * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)33      */34     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {35         // TODO Auto-generated method stub36         doGet(request, response);37     }38 39 }

而这里面，留意下有个注解

@WebServlet("/ServletDemo")

这个注解是eclipse帮我们生成好的，而问题恰恰就出在这。我们知道，每次我们新建一个servlet后会在web.xml文件中配置映射关系，这样才能在浏览器敲入一个地址后，地址发来的请求能让服务器接收到请求并将该请求交给指定的Servlet去处理。web.xml的作用就在此，它的代码如下：

<?xml version="1.0" encoding="UTF-8"?><web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xmlns="http://java.sun.com/xml/ns/javaee" 
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0">  <servlet>    <servlet-name>ServletDemo</servlet-name>    <servlet-class>com.vivizhang.servlet.HelloWorldServlet</servlet-class>  </servlet>  <servlet-mapping>    <servlet-name>ServletDemo</servlet-name>    <url-pattern>/HelloServlet</url-pattern>  </servlet-mapping></web-app>

所以问题的真相就是配置和自动生成的注解冲突了，导致如下的错误（截取）：

 A child container failed during startjava.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/ServletDemo]]    at java.util.concurrent.FutureTask$Sync.innerGet(FutureTask.java:252)    at java.util.concurrent.FutureTask.get(FutureTask.java:111)    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1120)    at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:819)    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1572)    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1562)    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)    at java.util.concurrent.FutureTask.run(FutureTask.java:166)    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)    at java.lang.Thread.run(Thread.java:722)Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/HelloServlet]]    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:153)    ... 7 moreCaused by: java.lang.IllegalArgumentException: The servlets named [ServletDemo] and [com.vivizhang.servlet.ServletDemo] are both mapped to the url-pattern [/ServletDemo] which is not permitted    at org.apache.catalina.deploy.WebXml.addServletMapping(WebXml.java:293)    at org.apache.catalina.startup.ContextConfig.processAnnotationWebServlet(ContextConfig.java:2462)    at org.apache.catalina.startup.ContextConfig.processAnnotationsStream(ContextConfig.java:2137)    at org.apache.catalina.startup.ContextConfig.processAnnotationsFile(ContextConfig.java:2098)    at org.apache.catalina.startup.ContextConfig.processAnnotationsFile(ContextConfig.java:2090)    at org.apache.catalina.startup.ContextConfig.processAnnotationsFile(ContextConfig.java:2090)    at org.apache.catalina.startup.ContextConfig.processAnnotationsFile(ContextConfig.java:2090)    at org.apache.catalina.startup.ContextConfig.processAnnotationsFile(ContextConfig.java:2090)    at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1304)    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:5472)    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)    ... 7 more九月 18, 2016 4:40:37 下午 org.apache.catalina.core.ContainerBase startInternalSEVERE: A child container failed during startjava.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost]]    at java.util.concurrent.FutureTask$Sync.innerGet(FutureTask.java:252)    at java.util.concurrent.FutureTask.get(FutureTask.java:111)    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1120)    at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:300)    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)    at org.apache.catalina.core.StandardService.startInternal(StandardService.java:444)    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)    at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:738)    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)    at org.apache.catalina.startup.Catalina.start(Catalina.java:693)    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)    at java.lang.reflect.Method.invoke(Method.java:601)    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:294)    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:428)Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost]]    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:153)    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1572)    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1562)    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)    at java.util.concurrent.FutureTask.run(FutureTask.java:166)    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)    at java.lang.Thread.run(Thread.java:722)Caused by: org.apache.catalina.LifecycleException: A child container failed during start    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1128)    at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:819)    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)    ... 7 more九月 18, 2016 4:40:37 下午 org.apache.catalina.startup.Catalina startSEVERE: The required Server component failed to start so Tomcat is unable to start.org.apache.catalina.LifecycleException: Failed to start component [StandardServer[8006]]    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:153)    at org.apache.catalina.startup.Catalina.start(Catalina.java:693)    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)    at java.lang.reflect.Method.invoke(Method.java:601)    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:294)    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:428)Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardService[Catalina]]    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:153)    at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:738)    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)    ... 7 moreCaused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina]]    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:153)    at org.apache.catalina.core.StandardService.startInternal(StandardService.java:444)    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)    ... 9 moreCaused by: org.apache.catalina.LifecycleException: A child container failed during start    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1128)    at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:300)    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)    ... 11 more

这里的问题出在：

The servlets named [ServletDemo] and [com.vivizhang.servlet.ServletDemo] are both mapped to the url-pattern [/ServletDemo] which is not permitted

故事解决办法：

　　可以选择删除web.xml中的映射，也可以选择将自动生成的注解注释掉，这样就不会有冲突了，二者选其一留下即可。

故事后续：

　　如果在其他问题都没出错的情况下，可能就是xml文件和注解出现了冲突，当然，出现这个问题的原因不止这一个，会有其他很多原因，去google吧，希望我的文章能帮助你解决实际的问题。

 转载自: http://www.cnblogs.com/vivizhang/p/vivizhang.html