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();
        }

 }
}