[求助]java.lang.ClassNotFoundException是什么异常！

我的程序在TOMCAT启动是有如下错误：
rg.apache.catalina.loader.StandardClassLoader@f449b8
com.yshine.hrs.presentation.base.BaseActionServlet
java.lang.ClassNotFoundException: com.yshine.hrs.presentation.base.BaseActionServlet
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1352)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1198)
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1034)
at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:932)
at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:3917)
at org.apache.catalina.core.StandardContext.start(StandardContext.java:4201)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:759)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:739)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:524)
at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:904)
at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:867)
at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:474)
at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1122)
at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:310)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1021)
at org.apache.catalina.core.StandardHost.start(StandardHost.java:718)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1013)
at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:442)
at org.apache.catalina.core.StandardService.start(StandardService.java:450)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:709)
at org.apache.catalina.startup.Catalina.start(Catalina.java:551)
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:585)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:294)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:432)
2006-10-30 20:14:37 org.apache.catalina.core.StandardContext loadOnStartup
严重: Servlet /WebRoot threw load() exception
java.lang.ClassNotFoundException: com.yshine.hrs.presentation.base.BaseActionServlet
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1352)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1198)
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1034)
at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:932)
at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:3917)
at org.apache.catalina.core.StandardContext.start(StandardContext.java:4201)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:759)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:739)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:524)
at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:904)
at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:867)
at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:474)
at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1122)
at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:310)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1021)
at org.apache.catalina.core.StandardHost.start(StandardHost.java:718)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1013)
at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:442)
at org.apache.catalina.core.StandardService.start(StandardService.java:450)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:709)
at org.apache.catalina.startup.Catalina.start(Catalina.java:551)
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:585)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:294)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:432)
有人知道是那里有问题吗？
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找不到类文件吧
把你的代码帖出来......
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com.yshine.hrs.presentation.base.BaseActionServlet
这个类找不到
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我知道了~~我是用ECLIPSE编写的，保存的时候会自动编译，但有时会不完全编译，刷新几边就OK了。

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