配置webwork遇到的问题，请大家指教。很着急！

刚刚接触webwork在试图配置工程的时候出现了一个问题，在eclipse下启动服务器，然后去访问自己的hello程序就会出现以下的异常。

javax.servlet.ServletException: Error allocating a servlet instance
	org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
	org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
	org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:856)
	org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:744)
	org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
	org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
	org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
	java.lang.Thread.run(Thread.java:595)


root cause 

java.lang.NoClassDefFoundError: javax/servlet/http/HttpServlet
	java.lang.ClassLoader.defineClass1(Native Method)
	java.lang.ClassLoader.defineClass(ClassLoader.java:620)
	java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124)
	java.net.URLClassLoader.defineClass(URLClassLoader.java:260)
	java.net.URLClassLoader.access$100(URLClassLoader.java:56)
	java.net.URLClassLoader$1.run(URLClassLoader.java:195)
	java.security.AccessController.doPrivileged(Native Method)
	java.net.URLClassLoader.findClass(URLClassLoader.java:188)
	java.lang.ClassLoader.loadClass(ClassLoader.java:306)
	sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:268)
	java.lang.ClassLoader.loadClass(ClassLoader.java:251)
	org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1247)
	org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1181)
	org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
	org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
	org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:856)
	org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:744)
	org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
	org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
	org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
	java.lang.Thread.run(Thread.java:595)

不用eclipse启动应用服务器，直接通过tomcat启动，然后去访问就正常，应该是servlet的jar包的问题，但搞了好长时间都不知道怎么搞定它，希望指导。在此谢过！

应该是classpath的问题，把tomcat下面的common\lib加到classpath环境变量里面试试？