sp.net中手写ajax检测用户是否存在？

RegisterGet.html

HTML code

    
      

     
       
     
       <
     
       html
     
       >
     
        
     
       <
     
       head
     
       >
     
        
     
       <
     
       title
     
       >
     
       Register
     
       </
     
       title
     
       >
     
        
     
       <
     
       script 
     
       type
     
       ="text/javascript"
     
       >
     
        
     
       //
     
       创建XMLHttpRequest对象函数
     
        
     
        
     
       function
     
        GetXMLHttpRequest() { 
     
       //
     
       这里应该根据浏览器版本判断，假设是ie，简单处理
     
        
     
        
     
       var
     
        xmlHttp 
     
       =
     
        
     
       new
     
        ActiveXObject(
     
       "
     
       Msxml2.XMLHTTP
     
       "
     
       ); 
     
       return
     
        xmlHttp; } 
     
       //
     
       当用户名文本框失去输入焦点时响应
     
        
     
        
     
       function
     
        checkUserName() { 
     
       //
     
        检查文本框是否有输入
     
        
     
        
     
       var
     
        txtUserName 
     
       =
     
        document.getElementById(
     
       '
     
       txtUserName
     
       '
     
       ); 
     
       if
     
        (txtUserName.value 
     
       ==
     
        
     
       ""
     
       ) 
     
       return
     
       ; xmlHttp 
     
       =
     
        GetXMLHttpRequest(); 
     
       //
     
        构造将XMLHttpRequest对象将请求的服务器端的URL字符串
     
        
     
        
     
       var
     
        url 
     
       =
     
        
     
       "
     
       CheckUserName.aspx?UserName=
     
       "
     
        
     
       +
     
        txtUserName.value; 
     
       //
     
        建立与服务器端的连接
     
        
     
        xmlHttp.open(
     
       "
     
       GET
     
       "
     
       , url, 
     
       true
     
       ); 
     
       //
     
        设置回调函数
     
        
     
        xmlHttp.onreadystatechange 
     
       =
     
        callBack_CheckUserName; 
     
       //
     
        发送请求
     
        
     
        xmlHttp.send(
     
       null
     
       ); } 
     
       //
     
       处理响应
     
        
     
        
     
       function
     
        callBack_CheckUserName() { 
     
       var
     
        lblMessage 
     
       =
     
        document.getElementById(
     
       "
     
       lblMessage
     
       "
     
       ); 
     
       //
     
        4代表服务器端执行完毕并已经成功返回
     
        
     
        
     
       if
     
        (
     
       4
     
        
     
       ==
     
        xmlHttp.readyState) { 
     
       if
     
       (
     
       200
     
        
     
       ==
     
        xmlHttp.status) { 
     
       //
     
       通过responseText属性得到服务器端实际返回的文本
     
        
     
        
     
       var
     
        isValid 
     
       =
     
        xmlHttp.responseText; 
     
       //
     
       根据isValid的值决定lblNameMessage的显示内容
     
        
     
        lblMessage.innerHTML 
     
       =
     
        (isValid.toLowerCase() 
     
       ==
     
        
     
       "
     
       true
     
       "
     
       ) 
     
       ?
     
        
     
       "
     
       用户名可用
     
       "
     
        : 
     
       "
     
       用户名已被注册
     
       "
     
       ; } } 
     
       else
     
        { lblMessage.innerHTML 
     
       =
     
        
     
       "
     
       数据查询中...
     
       "
     
       ; } } 
     
       </
     
       script
     
       >
     
        
     
       </
     
       HEAD
     
       >
     
        
     
       <
     
       body
     
       >
     
        
     
       <
     
       form 
     
       method
     
       ="post"
     
        action
     
       =""
     
       >
     
        
     
       <
     
       div
     
       >
     
        用户名: 
     
       <
     
       input 
     
       type
     
       ="text"
     
        id
     
       ="txtUserName"
     
        name
     
       ="txtUserName"
     
        onblur
     
       ="return checkUserName();"
     
       />
     
        
     
       <
     
       span 
     
       id
     
       ="lblMessage"
     
       ></
     
       span
     
       ><
     
       br
     
       >
     
        密
     
       &nbsp;&nbsp;&nbsp;&nbsp;
     
       码: 
     
       <
     
       input 
     
       type
     
       ="password"
     
        id
     
       ="txtPassword"
     
        name
     
       ="txtPassword"
     
        
     
       /><
     
       br
     
       >
     
        
     
       <
     
       input 
     
       type
     
       ="submit"
     
        id
     
       ="btnRegister"
     
        name
     
       ="btnRegister"
     
        value
     
       ="注册"
     
        
     
       />
     
        
     
       </
     
       div
     
       >
     
        
     
       </
     
       form
     
       >
     
        
     
       </
     
       body
     
       >
     
        
     
       </
     
       html
     
       >
    
      

CheckUserName.aspx.cs

C# code

    
      

     
       
     
       public
     
        
     
       partial
     
        
     
       class
     
        CheckUserName : System.Web.UI.Page { 
     
       protected
     
        
     
       void
     
        Page_Load(
     
       object
     
        sender, EventArgs e) { Response.Clear(); 
     
       string
     
        username 
     
       =
     
        Request.QueryString[
     
       "
     
       UserName
     
       "
     
       ];
     
       //
     
       Request["UserName"] 
     
       //
     
        模拟验证 实际应用中应查询数据库
     
        
     
        
     
       bool
     
        isValid 
     
       =
     
        
     
       false
     
       ; 
     
       if
     
        (String.Compare(username, 
     
       "
     
       amandag
     
       "
     
       , 
     
       true
     
       ) 
     
       !=
     
        
     
       0
     
       ) { isValid 
     
       =
     
        
     
       true
     
       ; } 
     
       //
     
        发送验证结果
     
        
     
        Response.ContentType 
     
       =
     
        
     
       "
     
       text/html
     
       "
     
       ; Response.Write(isValid.ToString()); Response.Flush(); Response.Close(); } }