ASP.NET文件下载函数

最新推荐文章于 2025-04-11 17:23:15 发布

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本文介绍了一个ASP.NET中用于文件下载的实用函数，该函数支持大文件下载、续传功能及速度限制，确保了资源占用小且能适应各种文件格式。

ASP.NET文件下载函数

文件下载函数代码为:

#region 下载文件

    /// <summary>
    /// 输出硬盘文件，提供下载支持大文件、续传、速度限制、资源占用小
    /// </summary>
    /// <param name="_Request">Page.Request对象</param>
    /// <param name="_Response">Page.Response对象</param>
    /// <param name="_fileName">下载文件名</param>
    /// <param name="_fullPath">带文件名下载路径</param>
    /// <param name="_speed">每秒允许下载的字节数</param>
    /// <returns>返回是否成功</returns>
    public static bool ResponseFile(HttpRequest _Request, HttpResponse _Response, string _fileName, string _fullPath, long _speed)
    {
        try
        {
            FileStream myFile = new FileStream(_fullPath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
            BinaryReader br = new BinaryReader(myFile);
            try
            {
                _Response.AddHeader("Accept-Ranges", "bytes");
                _Response.Buffer = false;
                long fileLength = myFile.Length;
                long startBytes = 0;

                double pack = 10240; //10K bytes
                //int sleep = 200;   //每秒5次   即5*10K bytes每秒
                int sleep = (int)Math.Floor(1000 * pack / _speed) + 1;
                if (_Request.Headers["Range"] != null)
                {
                    _Response.StatusCode = 206;
                    string[] range = _Request.Headers["Range"].Split(new char[] { '=', '-' });
                    startBytes = Convert.ToInt64(range[1]);
                }
                _Response.AddHeader("Content-Length", (fileLength - startBytes).ToString());
                if (startBytes != 0)
                {
                    //Response.AddHeader("Content-Range", string.Format(" bytes {0}-{1}/{2}", startBytes, fileLength-1, fileLength));
                }
                _Response.AddHeader("Connection", "Keep-Alive");
                _Response.ContentType = "application/octet-stream";
                _Response.AddHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(_fileName, System.Text.Encoding.UTF8));

br.BaseStream.Seek(startBytes, SeekOrigin.Begin);
int maxCount = (int)Math.Floor((fileLength - startBytes) / pack) + 1;

                for (int i = 0; i < maxCount; i++)
                {
                    if (_Response.IsClientConnected)
                    {
                        _Response.BinaryWrite(br.ReadBytes(int.Parse(pack.ToString())));
                        Thread.Sleep(sleep);
                    }
                    else
                    {
                        i = maxCount;
                    }
                }
            }
            catch
            {
                return false;
            }
            finally
            {
                br.Close();

                myFile.Close();
            }
        }
        catch
        {
            return false;
        }
        return true;
    }
    #endregion

调用示例代码:

    protected void btnCreateTemplet_Click(object sender, EventArgs e)
    {
        string srcFilePath = Server.MapPath("~/DownloadFiles/") + "TB_CellInfo.xls";
        string destFileName = "TB_CellInfo.xls";
        Page.Response.Clear();
        //bool success = ResponseFile(Page.Request, Page.Response, "目的文件名称", @"源文件路径", 1024000);
        bool success = ResponseFile(Page.Request, Page.Response, destFileName, srcFilePath, 1024000);
        if (!success)
        {
            Response.Write("下载文件出错！");
        }
        Page.Response.End();
    }

这样就实现了文件下载时,不管是什么格式的文件,都能够弹出打开/保存窗口.

参考 Leepy's Blog