<script type="text/javascript">
function getnodelist(){
  function onSuccess(request)
  {
      alert("success");
     $("result").innerHTML = "abc"+request.responseText ;
  }
  function onComplete(request){
  }
  function onFailure(request){
     alert("failure");
     $("result").innerHTML = request.responseText ;
  }
  var paras = "" ;
  var ajax = new Ajax.Request(
     "http://localhost:8080/LoginDemo/test.do",
    {
    method: 'post',
    parameters:paras ,
    onSuccess: onSuccess,
    onComplete:onComplete,
    onFailure:onFailure
   }
 );
}
</script>

var ajax = new Ajax.Request(   //新生成一个AJAX.Request对象.
 "http://localhost:8080/LoginDemo/test.do", //请求的servlet地址.即URL
 {                                //参数
  method: 'post',
  parameters:paras ,
  onSuccess: onSuccess,       //这些函数和上面三个函数相对应.
  onComplete:onComplete,
  onFailure:onFailure
 });

public ActionForward execute(
    ActionMapping mapping,
    ActionForm form,
    HttpServletRequest request,
    HttpServletResponse response) {
    // TODO Auto-generated method stub
    try{
      System.out.println("in action");
     response.setContentType("text/html;charset=gb2312");
      ServletOutputStream out = response.getOutputStream();
      out.print("hello slf!");
      System.out.println("out");
    }catch(Exception e)
    {
      e.printStackTrace();
    }
    return null;
  }