欢迎进入Java社区论坛，与200万技术人员互动交流 >>进入
最近项目中采用开启java线程来监听文件目录，在本地测试正常启动，但是当采用maven中的mvn tomcat:deploy部署到tomcat中时就报如下错误：
严重: Error listenerStart 2009-10-28 9:40:33 org.apache.catalina.core.StandardContext start 严重: Context [/cms] startup failed due to previous errors
09-10-28 09:40:34 DEBUG (cms.templet.TempletController:20) ? >>>>监听停止了!! 2009-10-28 9:40:34 org.apache.catalina.core.StandardContext listenerStop 严重: Exception sending context destroyed event to listener instance of class ut il.tools.ThemePicFileListenerTools java.lang.NullPointerException at util.tools.ThemePicFileListenerTools.contextDestroyed(ThemePicFileLis tenerTools.java:21) at org.apache.catalina.core.StandardContext.listenerStop(StandardContext .java:3882) at org.apache.catalina.core.StandardContext.stop(StandardContext.java:45 16) at org.apache.catalina.core.StandardContext.start(StandardContext.java:4 380) at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
at org.apache.catalina.core.StandardHost.start(StandardHost.java:719) at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:443 ) at org.apache.catalina.startup.Embedded.start(Embedded.java:825) at org.codehaus.mojo.tomcat.AbstractRunMojo.startContainer(AbstractRunMo jo.java:385) at org.codehaus.mojo.tomcat.AbstractRunMojo.execute(AbstractRunMojo.java :144) at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPlugi nManager.java:451) at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(Defa ultLifecycleExecutor.java:558) at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeStandalone Goal(DefaultLifecycleExecutor.java:512) at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(Defau ltLifecycleExecutor.java:482) at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHan dleFailures(DefaultLifecycleExecutor.java:330) at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegmen ts(DefaultLifecycleExecutor.java:291) at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLi fecycleExecutor.java:142) at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:336) at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:129) at org.apache.maven.cli.MavenCli.main(MavenCli.java:287) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl. java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces sorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315) at org.codehaus.classworlds.Launcher.launch(Launcher.java:255) at org.codehaus.classworlds.Launcher.mainWithExitCode(Launcher.java:430)
at org.codehaus.classworlds.Launcher.main(Launcher.java:375)
这个错误让我郁闷了好久，最后找到错误原因，是因为监听的文件夹下面没有内容，maven在发布项目的时候侯就不创建此文件夹，当程序启动的时候，找不到此目录，此时监听就会停止。报以上错误。
解决办法：把监听的目录下面加上相关的内容，利用maven发布版本的时候就可以创建监听文件夹，或在tomcat的工程下面手工创建监听文件即可。
游手好闲会使人心智生锈