PHP用户验证 PHP+Ajax验证码验证用户登录

 

<meta http-equiv="Content-Type" c type="text/css" href="%5Ccss%5Ca.css">
<style type="text/css">
<!--
  #main{
   font-family:宋体;
   font-size:10pt;
   text-align:center;
   margin-top:510px;
  }
  
  body{
   background-attachment:fixed;
   background-position:center;
   background-image:url(./images/w2.jpg);
   background-repeat: no-repeat;
  }
  
  #authCode{background-Color:#F8F9FF;}
  
  table{text-align:center;}

//-->
</style>
<script type="text/javascript" src="./js/trim.js"></script>
<script type="text/javascript">
<!--

 function clearX(){
  document.getElementById('authCode').value="";
 }

 // 点击图片重新获得新的验证码：
 function getVCode() { 
  var vcode=document.getElementById('vcode'); 
  vcode.src ='yz.php&#63;nocache='+new Date().getTime(); 
 }


 //定义XMLHttpRequest对象
 var xmlHttp;     

 // 创建 XMLHttpRequest:
 function createXmlHttpRequest(){
 var xmlHttp=null;
 try{
  // Firefox, Opera 8.0+, Safari
  xmlHttp=new XMLHttpRequest();
 }catch(e){
  // Internet Explorer
  try{
  xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
  }catch(e){
  xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
  }
 }
 return xmlHttp;
 }

 // AJAX 检查登录: 有密码，要用POST 提交
 function login(){
  var authCode=trim(document.getElementById('authCode').value);
  var username=trim(document.getElementById('username').value);
  var password=trim(document.getElementById('password').value);
  if(username=="" || password=="" || authCode==""){
   alert("请输入用户名和密码和验证码！");
   return false;
  }else{
   if(!xmlHttp) xmlHttp=createXmlHttpRequest();
    var send_string="username="+username+"&password="+password+"&authCode="+authCode+"&fresh="+Math.random();
    xmlHttp.open("POST","loginCheck.php",true); 
    xmlHttp.setRequestHeader("Content-Type","application/x-www-form-urlencoded"); 
    xmlHttp.send(send_string); 
    xmlHttp.
     if(xmlHttp.readystate==4 && xmlHttp.status==200){
      var answer=xmlHttp.responseText;
      if(answer=="ok")                     //跳转到管理中心页面
       window.location.href="adminCenter.php";
      else{
       alert("用户名密码或验证码不正确! 请重新输入!");
       document.getElementById('username').focus();
      }
    }
   }
  }
 }

//-->
</script>