当有两个不同名称，但是内容一样的项目，在tomcat中启动的问题解决

SEVERE: Exception sending context initialized event to listener instance of class org.springframework.web.util.Log4jConfigListener
java.lang.IllegalStateException: Web app root system property already set to different value: 'webapp.root' = [/usr/apache-tomcat-6.0.35/webapps/wms/] instead of [/usr/apache-tomcat-6.0.35/webapps/wmsFDC/] - Choose unique values for the 'webAppRootKey' context-param in your web.xml files!
 at org.springframework.web.util.WebUtils.setWebAppRootSystemProperty(WebUtils.java:147)
 at org.springframework.web.util.Log4jWebConfigurer.initLogging(Log4jWebConfigurer.java:117)
 at org.springframework.web.util.Log4jConfigListener.contextInitialized(Log4jConfigListener.java:45)
 at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4206)
 at org.apache.catalina.core.StandardContext.start(StandardContext.java:4705)
 at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:799)
 at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:779)
 at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:601)
 at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1079)
 at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:1002)
 at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:506)
 at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1317)
 at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:324)
 at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:142)
 at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1065)
 at org.apache.catalina.core.StandardHost.start(StandardHost.java:840)
 at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1057)
 at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:463)
 at org.apache.catalina.core.StandardService.start(StandardService.java:525)
 at org.apache.catalina.core.StandardServer.start(StandardServer.java:754)
 at org.apache.catalina.startup.Catalina.start(Catalina.java:595)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 at java.lang.reflect.Method.invoke(Method.java:597)
 at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289)
 at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414)

 看看异常，还是挺简单的，应该是两个项目的设置重复了，导致出错，但我发现web.xml里并没有配置webAppRootKey项
 原来是因为如果没有web.xm 内没有设置webAppRootKey项，是为默认设置

public  static  void  setWebAppRootSystemProperty(ServletContext servletContext) throws  IllegalStateException  {
       String  param = servletContext.getInitParameter(WEB_APP_ROOT_KEY_PARAM);
       String  key = (param != null  ? param : DEFAULT_WEB_APP_ROOT_KEY); 
       String  oldValue = System .getProperty(key); 
       if  (oldValue != null ) { 
           throw  new  IllegalStateException ("WARNING: Web app root system property already set: "  + key + " = "  + 
            oldValue + " - Choose unique webAppRootKey values in your web.xml files!" );
         } 
        String  root = servletContext.getRealPath("/" ); 
        if  (root == null ) { 
            throw  new  IllegalStateException ("Cannot set web app root system property when WAR file is not  expanded");
         } 
       System .setProperty(key, root); 
       servletContext.log("Set web app root system property: "  + key + " = "  + root);
     } 
在web.xml中加入
### app1:
<context-param>
    <param-name>webAppRootKey</param-name>
    <param-value>app1.root</param-value>
</context-param>

### app2:
<context-param>
    <param-name>webAppRootKey</param-name>
    <param-value>app2.root</param-value>
</context-param>