java.lang.ClassNotFoundException: com.lining.servlet.HW2无语了 整了一天了还是没整出来

package com.lining.servlet;import java.io.*;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse; public class HW2 extends javax.servlet.http.HttpServlet implements javax.servlet.Servlet {
   static final long serialVersionUID = 1L;
   
public HW2() {
super();
}   

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    PrintWriter out  =  response .getWriter();
    out.println("hellow!");
}  

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    this.doGet(request, response);
}           
}我写的jsp程序都可以运行出结果   这个servlet就不行！！！  恼火中！！快一天了  这一天我就整这个东西都没整出来！！   求大侠们指点呀！！！！！！！