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download.aspx

<% @ Page language="c#" Codebehind="download.aspx.cs" AutoEventWireup="false" Inherits="ZKSTAT.Common.download"  %>
<! DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"  >
< HTML >
     < HEAD >
         < title > download </ title >
         < meta  name ="GENERATOR"  Content ="Microsoft Visual Studio .NET 7.1" >
         < meta  name ="CODE_LANGUAGE"  Content ="C#" >
         < meta  name ="vs_defaultClientScript"  content ="JavaScript" >
         < meta  name ="vs_targetSchema"  content ="http://schemas.microsoft.com/intellisense/ie5" >
     </ HEAD >
     < body  MS_POSITIONING ="GridLayout" >
         < form  id ="Form1"  method ="post"  runat ="server" >
         </ form >
     </ body >
</ HTML >

download.cs

using  System;
using  System.IO;
using  System.Web;
using  System.Web.UI;

namespace  ZKSTAT.Common
{
    /**//// <summary>
    /// download 的摘要说明。
    /// </summary>
    public class download : System.Web.UI.Page
    {
        private void Page_Load(object sender, EventArgs e)
        {
            // 在此处放置用户代码以初始化页面
            string path = Request.Params["download"];
            if(path == null) return;
            Stream stream = null;           // Buffer to read 10K bytes in chunk:
            byte[] buffer = new Byte[10240];

            // Length of the file:
            int length;

            // Total bytes to read:
            long dataToRead;

            // Identify the file to download including its path.
            string path2 = Request.PhysicalPath;
            path2 = path2.Substring ( 0,path2.LastIndexOf ( "Common\\" ) );
            string filepath  = path2 +"UploadFile/Files/" + path;
            //filepath = Server.MapPath ( filepath );

            // Identify the file name.
            string  filename  = Path.GetFileName(filepath);

            try
            {
                // Open the file.
                stream = new FileStream(filepath, FileMode.Open, 
                                        FileAccess.Read,FileShare.Read);
                Response.Clear();

                // Total bytes to read:
                dataToRead = stream.Length;

                long p = 0;
                if(Request.Headers["Range"]!=null)
                {
                    Response.StatusCode = 206;
                    p = long.Parse( Request.Headers["Range"].Replace("bytes=","").Replace("-",""));
                }
                if(p != 0)
                {
                    Response.AddHeader("Content-Range","bytes " + p.ToString() + "-" + ((long)(dataToRead - 1)).ToString() + "/" + dataToRead.ToString());                    
                }
                Response.AddHeader("Content-Length",((long)(dataToRead-p)).ToString());
                Response.ContentType = "application/octet-stream";
                Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(Request.ContentEncoding.GetBytes(filename)));

                stream.Position = p;
                dataToRead = dataToRead - p;
                // Read the bytes.
                while (dataToRead > 0)
                {
                    // Verify that the client is connected.
                    if (Response.IsClientConnected) 
                    {
                        // Read the data in buffer.
                        length = stream.Read(buffer, 0, 10240);

                        // Write the data to the current output stream.
                        Response.OutputStream.Write(buffer, 0, length);

                        // Flush the data to the HTML output.
                        Response.Flush();

                        buffer= new Byte[10240];
                        dataToRead = dataToRead - length;
                    }
                    else
                    {
                        //prevent infinite loop if user disconnects
                        dataToRead = -1;
                    }
                }
            }
            catch (Exception ex) 
            {
                // Trap the error, if any.
                Response.Write("错误 : " + ex.Message);
            }
            finally
            {
                if (stream != null) 
                {
                    //Close the file.
                    stream.Close();
                }
                Response.End();
            }
        }

        Web 窗体设计器生成的代码#region Web 窗体设计器生成的代码
        override protected void OnInit(EventArgs e)
        {
            //
            // CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。
            //
            InitializeComponent();
            base.OnInit(e);
        }
        
        /**//// <summary>
        /// 设计器支持所需的方法 - 不要使用代码编辑器修改
        /// 此方法的内容。
        /// </summary>
        private void InitializeComponent()
        {    
            this.Load += new EventHandler(this.Page_Load);
        }
        #endregion
    }
}