java.lang.IllegalStateException: Web app root system property already set to different value: 'web.sample.root' = [C:\1.Software\work\Apache Software Foundation\Tomcat 8.0\webapps\alipaysevice] instead of [C:\1.Software\work\Apache Software Foundation\Tomcat 8.0\webapps\wcyld] - Choose unique values for the 'webAppRootKey' context-param in your web.xml files!
at org.springframework.web.util.WebUtils.setWebAppRootSystemProperty(WebUtils.java:162)
at org.springframework.web.util.Log4jWebConfigurer.initLogging(Log4jWebConfigurer.java:119)
at org.springframework.web.util.Log4jConfigListener.contextInitialized(Log4jConfigListener.java:49)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4710)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5135)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1409)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1399)
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)
错误内容，这是在我本地时错误所报的内容，我同时将两个项目放到tomcat下了，然后启动报错，错误原因是因为WEB.XML里面的key重复了。
<param-name>webAppRootKey</param-name>
<param-value>XXX</param-value>
两个项目的配置文件是我自己复制过去的。只要修改下面的key，两个项目都可以访问了。。。
然而，我的服务器报错却不是这样。。服务器报错
this web application instance has been stopped already.
我的天，他说我tomcat 启动的原因，说是上次tomcat的线程还没有完全关闭，最新启动tomcat就会报这个异常。。最终解决改掉webxml里面的文件。。