利用ICallbackEventHandle实现类似AJAX的无刷新页面

先看MSDN Library 2005上的这个例子！
------ ClientCallback.aspx ------

<% @ Page Language = " C# "  AutoEventWireup = " true "  CodeFile = " ClientCallback.aspx.cs "  ­ Inherits = " ClientCallback "   %>

<! DOCTYPE html PUBLIC  " -//W3C//DTD XHTML 1.1//EN "   " http://www.w3.org/TR/xhtml11/DTD/­ xhtml11.dtd " >

< html xmlns = " http://www.w3.org/1999/xhtm­ l "   >
     < head id = " Head1 "  runat = " server " >
         < title > Callback Test </ title >
         < script type = " text/javascript " >
        function ReceiveServerData(receivedStr, context)
         {
            alert(receivedStr);
        }
         </ script >
     </ head >
         < body >
           < form id = " form1 "  runat = " server " >
             < input type = " button "  value = " Callback "  onclick = " CallServer('argument', 'context') " />< br  />
           </ form >
     </ body >
</ html >

-------- ClientCallbacp.aspx.cs  -----------

//  ClientCallback.aspx.cs 
using  System;
using  System.Data;
using  System.Configuration;
using  System.Collections;
using  System.Web;
using  System.Web.Security;
using  System.Web.UI;
using  System.Web.UI.WebControls;
using  System.Web.UI.WebControls.WebParts;­ 
using  System.Web.UI.HtmlControls;

public  partial  class  ClientCallback : System.Web.UI.Page, System.Web.UI.ICallbackEventHandle­ r
{

    void Page_Load(object sender, EventArgs e)
    {
        ClientScriptManager cm = Page.ClientScript;
        String cbReference = cm.GetCallbackEventReference(this,­ "arg", "ReceiveServerData", "");
        String callbackScript = "function CallServer(arg, context) {" + cbReference + "; }";
        cm.RegisterClientScriptBlock(this.­ GetType(), "CallServer", callbackScript, true);
    }

    private string returnStr;
    //function called by client, executed on server
    public void RaiseCallbackEvent(String eventArgument)    
    {
        //do something with return argument
        returnStr = eventArgument.ToUpper();
        return;
    }
    
    //function that sends result?
    public string GetCallbackResult()
    {
        return returnStr;
    }
}

客户端用 ReceiveServerData接收服务器返回的数据，
<script type="text/javascript">
        function ReceiveServerData(receivedStr, context)
        {
            alert(receivedStr);
        }
 </script>

使用 CallServer('argument', 'context')传递数据到服务器。

客户端ok了，接下来是服务器端，
实现 ICallbackEventHandle­ 接口，
private string returnStr;
 public void RaiseCallbackEvent(String eventArgument)    
    {
        returnStr = eventArgument.ToUpper();
        return;
    }
    
public string GetCallbackResult()
    {
        return returnStr;
    }

最后，将客户端方法和服务器端的方法关联起来，在 Page_Load中实现，
ClientScriptManager cm = Page.ClientScript;
 String cbReference = cm.GetCallbackEventReference(this,­ "arg", "ReceiveServerData", "");
String callbackScript = "function CallServer(arg, context) {" + cbReference + "; }";
 cm.RegisterClientScriptBlock(this.­ GetType(), "CallServer", callbackScript, true);

大功告成！

这种方法也能达到类似ajax的无刷新页面，而且实现起来十分简单。