Ajax实现漂亮、安全的登录界面

<div style="margin-left:50px; margin-top:50px; ">
欢迎使用后台，
<a href="Login.htm?TB_iframe&height=180&width=350&modal=true" class="thickbox" id="myToolTip" title="点击登录，进入后台管理" >
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<script type="text/javascript" src="js/jquery-1.3.2.js"></script>
<script type="text/javascript">
 $().ready(function () {
  $('#Login').click(function () {
   if ($('#username').val() == "" || $('#password').val() == "") {
    alert("用户名或密码不能为空！");
   }
   else {
    $.ajax({
     type: "POST",
     url: "Ajax/LoginHandler.ashx",
     data: "username=" + escape($('#username').val()) + "&password=" + escape($('#password').val()),
     beforeSend: function () {
      $("#loading").css("display", "block"); //点击登录后显示loading，隐藏输入框
      $("#login").css("display", "none");
     },
     success: function (msg) {
      $("#loading").hide(); //隐藏loading
      if (msg == "success") {
       //parent.tb_remove();
       parent.document.location.href = "admin.htm"; //如果登录成功则跳到管理界面
       parent.tb_remove();
      }
      if (msg == "fail") {
       alert("登录失败！");
      }
     },
     complete: function (data) {
      $("#loading").css("display", "none"); //点击登录后显示loading，隐藏输入框
      $("#login").css("display", "block");
     },
     error: function (XMLHttpRequest, textStatus, thrownError) {
     }
    });
   }
  });
 });
</script>
<div id="loading" style="text-align: center; display: none; padding-top: 10%">
 <img src="images/loadingajax.gif" alt="loading" />
</div>
<div id="login" style="text-align: center">
<div style="position:absolute; right:0; top:0"><img src="images/closebox.png" onclick="parent.tb_remove()" alt="点击关闭" style="cursor:pointer" /></div>
 <table border="0" cellpadding="3" cellspacing="3" style="margin: 0 auto;">
  <tr>
   <td style="text-align: right; padding: 10px">
    <label>
     用户名:</label>
   </td>
   <td>
    <input id="username" type="text" size="20" />
   </td>
  </tr>
  <tr>
   <td style="text-align: right; padding: 10px">
    <label>
     密码:</label>
   </td>
   <td>
    <input id="password" type="password" size="20" />
   </td>
  </tr>
  <tr align="right">
   <td colspan="2">
    <input type="submit" id="Login" value="&nbsp;&nbsp;登&nbsp;录&nbsp;&nbsp;" style="margin-right: 50px">&nbsp;
    <input type="submit" id="LoginCancel" value="&nbsp;&nbsp;取&nbsp;消&nbsp;&nbsp;" onclick="parent.tb_remove()">
   </td>
  </tr>
 </table>
</div>

string username = context.Request["username"].ToString();
string password = context.Request["password"].ToString();
//context.Response.Write(password);如果使用加密，则写入数据库要加密后的字段，然后登陆的时候就用加密后的字符串匹配
//此处连接数据库查看是否有此用户，此处为了方便起见，直接判断
if (username == "admin" && password == "1")
 {
 context.Response.Write("success");
 //存储session
 }
 else
 {
 context.Response.Write("fail");
 }

data: "username=" + escape($('#username').val()) + "&password=" + $.md5(escape($('#password').val())),

success: function (msg) {
      $("#loading").hide(); //隐藏loading
      alert(msg);
      if (msg == "success") {
       //parent.tb_remove();
       parent.document.location.href = "admin.htm"; //如果登录成功则跳到管理界面
       parent.tb_remove();
      }
      if (msg == "fail") {
       alert("登录失败！");
      }
     }