ajax的验证用户是否正确的,,有点不明白
<html>
   <head>
     <title>judegUsername.axpx</title>  
     <meta http-equiv="content-type" content="text/html; charset=UTF-8">      
     <script language="JavaScript" type="text/javascript">
     var request = false;
     try{
      request = new XMLHttpRequest();
     }catch(microsoftIE){
      try{
       request = new ActiveXObject("Msxml2.XMLHTTP");
      }catch(microsoftOldIE){
       try{
        request = new ActiveXObject("Microsoft.XMLHTTP");
       }catch(failed){
        request = false;
       }
      }
     }
     if(!request){
      alert("初始化XMLHttpRequest对象失败");
     }
     function sendUsername(){
      var username = document.getElementById("username").value;
      if(username!=null && username!=""){
       var url = "./judgeUsername.axpx?username="+escape(username);
       request.open("get",url,true);
       request.onreadystatechange=updatepage;
       request.send(null);
      }
     }
     function updatepage(){
      if(request.readyState==4){
       if(request.status==200){
        document.getElementById("reusername").innerHTML = request.responseText;
        //document.getDocumentById("reusername").innerText = request.responseText;
       }else if(request.status==404){
        alert("找不到页面!");
       }else{
        alert("错误代码:"+request.status);
       }
      }
     }
     function clearMessage(){
      document.getElementById("reusername").innerHTML = "";
     }
     </script>
   </head>    
   <body>
    <form action="/register.jsp" method="post">
     <table align="center">
      <caption>guoyongfei为已注册,其他均未注册</caption>
      <tr><th>用 户 名:</th><td><input type="text" name="username" id="username" onblur="sendUsername()" onfocus="clearMessage()"/></td><td width="40%" id="reusername"></td></tr>
      <tr><th style="height: 26px">密  码:</th><td style="height: 26px"><input type="password" name="password" id="password"/></td><td width="20" style="height: 26px"></td></tr>
      <tr><th>密码确认:</th><td><input type="text" name="surePassword" id="surePassword"/></td><td width="20"></td></tr>
     </table>
   </body>
</html>
在另一个弹出页面 judgeUsername.axpx 的page_load:
//这里要写什么?
         //System.out.println("username:"+username);
         if (username.Equals ("guoyongfei"))
         {
             Response.Write("<font color='red'>用户名已经注册</font>");
         }
         else
         {
             Response.Write("<font color='green'>用户名可以用</font>");
         }  
------解决方案--------------------