eclipse中启动tomcat时出现问题，好像是编码过滤器有问题，错误如下

信息: Starting service Catalina
 2011-11-12 14:21:55 org.apache.catalina.core.StandardEngine start
 信息: Starting Servlet Engine: Apache Tomcat/6.0.18
 2011-11-12 14:21:56 org.apache.catalina.core.StandardContext filterStart
 严重: Exception starting filter filter
 java.lang.ClassNotFoundException: com.cn.filter.Zh_Filter
  at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1387)
  at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1233)
  at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:249)
  at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:397)
  at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:108)
  at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:3709)
  at org.apache.catalina.core.StandardContext.start(StandardContext.java:4363)
  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.core.StandardService.start(StandardService.java:516)
  at org.apache.catalina.core.StandardServer.start(StandardServer.java:710)
  at org.apache.catalina.startup.Catalina.start(Catalina.java:578)
  at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
  at java.lang.reflect.Method.invoke(Unknown Source)
  at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:288)
  at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:413)
 2011-11-12 14:21:56 org.apache.catalina.core.StandardContext start
 严重: Error filterStart
 2011-11-12 14:21:56 org.apache.catalina.core.StandardContext start
 严重: Context [/JSP2] startup failed due to previous errors
 2011-11-12 14:21:56 org.apache.coyote.http11.Http11Protocol start
 信息: Starting Coyote HTTP/1.1 on http-8080
 2011-11-12 14:21:56 org.apache.jk.common.ChannelSocket init
 信息: JK: ajp13 listening on /0.0.0.0:8009
 2011-11-12 14:21:56 org.apache.jk.server.JkMain start
 信息: Jk running ID=0 time=0/15  config=null
 2011-11-12 14:21:56 org.apache.catalina.startup.Catalina start
 信息: Server startup in 1004 ms