网上已经有很多Web进度条的例子，但是很多都是估算时间，不能正真反应任务的真实进度。我自己结合多线程和ShowModalDialog制做了一个实时进度条，原理很简单：使用线程开始长时间的任务，定义一个Session，当任务进行到不同的阶段改变Session的值，线程开始的同时使用ShowModalDialog打开一个进度条窗口，不断刷新这个窗口获取Session值，反应出实时的进度。下面就来看看具体的代码：（文章结尾处下载源代码）
先新建一个Default.aspx页面，
客户端代码：
<body MS_POSITIONING="GridLayout">
<form method="post" runat="server">
<br>
<br>
<asp:Button runat="server" Text="Start Long Task!"></asp:Button>
</form>
</body>
服务器端代码：
using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Text;
namespace WebProgressBar
{
/**//// <summary>
/// Summary description for _Default.
/// </summary>
public class _Default : System.Web.UI.Page
{
protected System.Web.UI.WebControls.Button Button1;
private void Page_Load(object sender, System.EventArgs e)
{
// Put user code to initialize the page here
}
Web Form Designer generated code#region Web Form Designer generated code
override protected void OnInit(EventArgs e)
{
//
// CODEGEN: This call is required by the ASP.NET Web Form Designer.
//
InitializeComponent();
base.OnInit(e);
}
/**//// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
this.Button1.Click += new System.EventHandler(this.Button1_Click);
this.Load += new System.EventHandler(this.Page_Load);
}
#endregion
private void LongTask()
{
//模拟长时间任务
//每个循环模拟任务进行到不同的阶段
for(int i=0;i<11;i++)
{
System.Threading.Thread.Sleep(1000);
//设置每个阶段的state值，用来显示当前的进度
Session["State"] = i+1;
}
//任务结束
Session["State"] = 100;
}
public static void OpenProgressBar(System.Web.UI.Page Page)
{
StringBuilder sbScript = new StringBuilder();
sbScript.Append("<script language='JavaScript' type='text/javascript'>\n");
sbScript.Append("<!--\n");
//需要IE5.5以上支持
sbScript.Append("window.showModalDialog('Progress.aspx','','dialogHeight: 100px; dialogWidth: 350px; edge: Raised; center: Yes; help: No; resizable: No; status: No;scroll:No;');\n");
//IE5.5以下使用window.open
//sbScript.Append("window.open('Progress.aspx','', 'height=100, width=350, toolbar =no, menubar=no, scrollbars=no, resizable=no, location=no, status=no');\n");
sbScript.Append("// -->\n");
sbScript.Append("</script>\n");
Page.RegisterClientScriptBlock("OpenProgressBar", sbScript.ToString());
}