Exception starting filter struts2!!!

严重: Exception starting filter struts2
java.lang.ClassNotFoundException: org.apache.struts2.dispatcher.FilterDispatcher
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1355)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1201)
at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:209)
at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:304)
at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:77)
at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:3634)
at org.apache.catalina.core.StandardContext.start(StandardContext.java:4217)
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.deployWAR(HostConfig.java:809)
at org.apache.catalina.startup.HostConfig.deployWARs(HostConfig.java:698)
at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:472)
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:597)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:294)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:432)
2010-3-19 12:11:56 org.apache.catalina.core.StandardContext start
严重: Error filterStart
2010-3-19 12:11:56 org.apache.catalina.core.StandardContext start
严重: Context [/Struts] startup failed due to previous errors
2010-3-19 12:11:56 org.apache.catalina.core.ApplicationContext log所用包为commons-logging-api-1.1.jar、freeer.jar、ognl-2.6.11.jar、struts2-core-2.0.12.jar、xwork-2.0.6.jar还加了一个commons-fileupload-1.2.1.jar。
web.xml:
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee 
 http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
 <filter>
    <filter-name>struts</filter-name>
    <filter-class>org.apache.struts2.dispatcher.FilterDispatcher</filter-class>
 </filter>
 <filter-mapping>
      <filter-name>struts</filter-name>
          <url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>早上一直在找原因，网上的解答都不能解决。环境MyEclipse5.5、struts2
求解。。