Servlet.service() for servlet action threw exception出错！！！！ 急喔
*/
public   ActionForward   execute(ActionMapping   mapping,   ActionForm   form,
HttpServletRequest   request,   HttpServletResponse   response)   {
DynaValidatorForm   loginForm   =   (DynaValidatorForm)   form;//   TODO   Auto-generated   method   stub
String   username=loginForm.getString( "userName ");
String   password=loginForm.getString( "password ");
if(request.getAttribute( "rand ").equals(loginForm.getString( "rand "))&&userServiceImp.isUser(username,   password))
{       HttpSession   session=request.getSession();
        Users   us=userServiceImp.getUsersDAO().findByUName(username);
       
        ApplicationContext   context   =   new   FileSystemXmlApplicationContext( "C://workspace//bookstore//WebRoot//WEB-INF//applicationContext.xml ");
        RandomValus       randomValus=new   RandomValus();  
        MD5   md5=new   MD5();
        String   code=md5.getMD5Instance().compute(randomValus.getRandomStr()).toUpperCase();
        session.setAttribute( "name ",username);
        session.setAttribute( "code ",   code);
        MapperIF   mapper   =(MapperIF)context.getBean( "net.sf.dozer.util.mapping.MapperIF ");
Users_static   users_static=   (Users_static)   mapper.map(us,Users_static.class);
Vector   userslist=new   Vector();
userslist.add(users_static);
session.setAttribute( "users ",   userslist);
return   mapping.findForward( "success ");}
else   return   mapping.findForward( "faild ");
}
}

我的login.jsp
  <h5> 登录 </h5>
                <form   id= "form1 "     method= "post "   action= "login.do ">
                    <label> 用户名
                        <input   name= "userName "   type= "text "/>
                    <a   href= "register_step_one.do "   target= "_blank "   class= "font00F "> 注册新用户 </a> </label>
                    <label> 密　码
                    <input   name= "password "   type= "password "/>
                    </label>
                    <label> 验证码
                    <input   name= "rand "   size= "5 "   type= "text "/>
                  <img   id= "rand_img "   src= "VerifyCode.jsp "     width= "75 "   hei