ServerControl : RequestProcesser

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Web.UI;
using System.IO;

namespace Bruce.Web.Controls
{
    public class RequestProcesser : Control
    {
        /// <summary>
        /// 送出Request前的動作
        /// </summary>
        public string OnBeginRequest { get; set; }
        /// <summary>
        /// 收到Response後的動作
        /// </summary>
        public string OnEndRequest { get; set; }
        /// <summary>
        /// JavaScript物件名稱
        /// </summary>
        private string ObjectName = "__RequestProcesser";

        protected override void OnPreRender(EventArgs e)
        {
            ScriptManager sm = ScriptManager.GetCurrent(this.Page);
            if (sm == null)
            {
                string script = string.IsNullOrEmpty(this.OnBeginRequest)
                    ? "document.getElementById('" + this.ClientID + "').style.display = 'block';"
                    : string.Format(@"
if((function(){{{0}}})() == false){{
    return false;
}}else{{
    document.getElementById('{1}').style.display = 'block';
    return true;
}}", this.OnBeginRequest, this.ClientID);
                this.Page.ClientScript.RegisterOnSubmitStatement(this.Page.GetType(), "OnBeginRequest", script);
            }
            else
            {
                this.Page.ClientScript.RegisterStartupScript(this.Page.GetType(), "Processing", string.Format(@"
var {3} = {{
    OnBeginRequest: function() {{
        if((function(){{{1}}})() == false){{
            return false;
        }}else{{
            document.getElementById('{0}').style.display = 'block';
            return true;
        }}
    }},
    OnEndRequest: function() {{
        document.getElementById('{0}').style.display = 'none';
        (function(){{{2}}})();
    }}
}};
//Sys.WebForms.PageRequestManager.getInstance().add_beginRequest({3}.OnBeginRequest);
Sys.WebForms.PageRequestManager.getInstance().add_endRequest({3}.OnEndRequest);
", this.ClientID, this.OnBeginRequest, this.OnEndRequest, ObjectName), true);
                this.Page.ClientScript.RegisterOnSubmitStatement(this.Page.GetType(), "OnBeginRequest", "return " + ObjectName + ".OnBeginRequest();");
            }
            base.OnPreRender(e);
        }

        protected override void Render(HtmlTextWriter writer)
        {
            writer.WriteBeginTag(string.Format("div id=\"{0}\" style=\"display:none;\">", this.ClientID));
            base.Render(writer);
            writer.WriteEndTag("div");
        }
    }
}