教你制做Web实时进度条

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 id="Form1" method="post" runat="server">
            <br>
            <br>
            <asp:Button id="Button1" 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");
            sbScript.Append("</script>\n");

Page.RegisterClientScriptBlock("OpenProgressBar", sbScript.ToString());
}

        private void Button1_Click(object sender, System.EventArgs e)
        {
            System.Threading.Thread thread=new System.Threading.Thread(new System.Threading.ThreadStart(LongTask));
            thread.Start();

            Session["State"]=1;
            OpenProgressBar(this.Page);
        }
    }
}

新建一个进度条页面Progress.aspx
客户端：
在head中加入<base target="_self">
<body MS_POSITIONING="GridLayout">
        <form id="Form1" method="post" runat="server">
            <asp:Label id="lblMessages" runat="server"></asp:Label>
            <asp:Panel id="panelBarSide" runat="server" Width="300px" BorderStyle="Solid" BorderWidth="1px"
                ForeColor="Silver">
                <asp:Panel id="panelProgress" runat="server" Width="10px" BackColor="Green"></asp:Panel>
            </asp:Panel>
            <asp:Label id="lblPercent" runat="server" ForeColor="Blue"></asp:Label>
        </form>
</body>
服务器端：
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;

namespace WebProgressBar
{
    /**//// <summary>
    /// Summary description for Progress.
    /// </summary>
    public class Progress : System.Web.UI.Page
    {
        protected System.Web.UI.WebControls.Label lblMessages;
        protected System.Web.UI.WebControls.Panel panelProgress;
        protected System.Web.UI.WebControls.Panel panelBarSide;
        protected System.Web.UI.WebControls.Label lblPercent;

        private int state = 0;
        private void Page_Load(object sender, System.EventArgs e)
        {
            // Put user code to initialize the page here
            if(Session["State"]!=null)
            {
                state = Convert.ToInt32(Session["State"].ToString());
            }
            else
            {
                Session["State"]=0;
            }
            if(state>0&&state<=10)
            {
                this.lblMessages.Text = "Task undertaking!";
                this.panelProgress.Width = state*30;
                this.lblPercent.Text = state*10 + "%";
                Page.RegisterStartupScript("","<script>window.setTimeout('window.Form1.submit()',100);</script>");
            }
            if(state==100)
            {
                this.panelProgress.Visible = false;
                this.panelBarSide.Visible = false;
                this.lblMessages.Text = "Task Completed!";
                Page.RegisterStartupScript("","<script>window.close();</script>");
            }
        }