asp.net回调javascript

using System; 
using System.Collections; 
using System.IO; 
using System.Text; 
using System.Web; 
using System.Web.UI; 
using System.Web.UI.WebControls; 
using System.ComponentModel; 
namespace Platform 
{ 
 
 
 /// <summary> 
 /// 可以处理客户端的jscript的回调 
 /// </summary> 
 [DefaultProperty(""), 
  ToolboxData("<{0}:ScriptCallbackManager runat=server></{0}:ScriptCallbackManager>")] 
 public class ScriptCallbackManager : System.Web.UI.WebControls.WebControl 
 { 
  private ICallbackEventHandler _handler; 
  private String _functionNameAfterCallback; 
        public ScriptCallbackManager() { 
            //_handler = (ICallbackEventHandler)Page; 
        }

        /// <summary> 
        /// 回调完执行的客户端函数 
        /// </summary> 
  public string FunctionNameAfterCallback 
  { 
   get { return _functionNameAfterCallback; } 
            set { _functionNameAfterCallback = value; } 
  } 
  public ICallbackEventHandler CallbackEventHandler 
  { 
   get { return _handler; } 
            set { _handler = value; } 
  }
  /// <summary> 
  /// 将此控件呈现给指定的输出参数。 
  /// </summary> 
  /// <param name="output"> 要写出到的 HTML 编写器 </param> 
  protected override void Render(HtmlTextWriter output) 
  { 
   output.Write(this.GetCallbackEventReference()); 
  } 
  protected override void OnInit(EventArgs e){ 
   base.OnInit(e); 
   try { 
    this.HandleRequest(); 
            } 
   catch (Exception ex){ 
                object o = ex; 
   } 
  } 
  private void HandleRequest(){ 
   HttpRequest request = this.Page.Request; 
   HttpResponse reponse = this.Page.Response; 
   String sType = request["type"]; 
   if ((sType != null) && (sType == "__scriptcallback:" + this.ID)) 
   { 
    String sRequest = this.GetRequestContent(request); 
    String sResult = this.CallHandler(sRequest); 
    reponse.Clear(); 
    reponse.Expires = 0; 
    reponse.Write(sResult); 
    reponse.End(); 
   } 
  } 
  private String GetRequestContent(HttpRequest request) { 
   HttpRequest r = request; 
   String s = r.ToString(); 
   using (StreamReader reader = new StreamReader(request.InputStream)) { 
    return reader.ReadToEnd(); 
   } 
  } 
        private String CallHandler(String param) { 
            if (this.CallbackEventHandler != null) { 
                return this.CallbackEventHandler.RaiseCallbackEvent(this, param); 
            } 
            return ""; 
        } 
  /* 
  private ICallbackEventHandler GetScriptCallbackHandlerOnPage(String id) 
  { 
   return this.GetScriptCallbackHandler(this.Page, id); 
  } 
  private ICallbackEventHandler GetScriptCallbackHandler(Control control, String id) 
  { 
   if ((control is ICallbackEventHandler) && (control.ID == id)) 
   { 
    return control as ICallbackEventHandler; 
   } 
   foreach(Control child in control.Controls) 
   { 
    ICallbackEventHandler handler = GetScriptCallbackHandler(child, id); 
    if (handler != null) 
    { 
     return handler; 
    } 
   } 
   return null; 
  } 
  */ 
        private String GetCallbackEventReference() 
        { 
         StringBuilder sb = new StringBuilder(); 
   sb.Append("<script>"); 
   sb.Append("function " + this.ID + "(param, context) {"); 
   sb.Append("var xmlhttp = new ActiveXObject('Msxml2.XMLHTTP');"); 
   sb.Append("xmlhttp.Open('POST', '" + HttpContext.Current.Request.Url.ToString() + "?type=__scriptcallback:" + this.ID + "', false);"); 
   sb.Append("xmlhttp.Send(param);"); 
   sb.Append(this.FunctionNameAfterCallback + "(xmlhttp.responseText, context);"); 
   sb.Append("}"); 
   sb.Append("</script>"); 
   return sb.ToString(); 
        } 
 } 
}