.net中如何下载

Question

    数据库中存在文件的路径，如何下载数据库中指定路径的文件？

Answer 1

        private void downfile()
        {
            string FileName;
            WebClient DownFile = new WebClient();
            long fbytes;
            if (textBox1.Text != "")
            {
                saveFileDialog1.ShowDialog();
                FileName = saveFileDialog1.FileName;
                if (FileName != "")
                {
                    //取得文件大小
                    WebRequest wr_request = WebRequest.Create(textBox1.Text);
                    WebResponse wr_response = wr_request.GetResponse();
                    fbytes = wr_response.ContentLength;
                    progressBar1.Maximum = (int)fbytes;
                    progressBar1.Step = 1;
                    wr_response.Close();
                    //开始下载数据
                    DownFile.DownloadData(textBox1.Text);
                    Stream strm = DownFile.OpenRead(textBox1.Text);
                    StreamReader reader = new StreamReader(strm);
                    byte[] mbyte = new byte[fbytes];
                    int allmybyte = (int)mbyte.Length;
                    int startmbyte = 0;
                    while (fbytes > 0)
                    {
                        int m = strm.Read(mbyte, startmbyte, allmybyte);
                        if (m == 0) break;
                        startmbyte += m;
                        allmybyte -= m;
                        progressBar1.value += m;
                    }
                    FileStream fstrm = new FileStream(FileName, FileMode.OpenOrCreate, FileAccess.Write);
                    fstrm.Write(mbyte, 0, startmbyte);
                    strm.Close();
                    fstrm.Close();
                    progressBar1.value = progressBar1.Maximum;
                }
            }
            else
            {
                MessageBox.Show("没有输入要下载的文件！");
            }
        } 自己完善一下

Answer 2

直接输出超链接，链接地址就是数据库中的地址
<a href="文件路径">文件标题</a>

Answer 3

2楼的理解是对的，这个思路我也知道，但是我不会写代码啊
例如:表 news 字段filestr中存在该文件的路径。我改如何取这个路径呢？这个超链接应该写在哪里？能写详细一点的代码吗？

Answer 4

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.IO;
using System.Threading;public class Download
{
    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;                int pack = 10240; //10K bytes
                //int sleep = 200; //每秒5次 即5*10K bytes每秒
                int sleep = (int)Math.Floor((decimal)(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((decimal)((fileLength - startBytes) / pack)) + 1;                for (int i = 0; i < maxCount; i++)
                {
                    if (_Response.IsClientConnected)
                    {
                        _Response.BinaryWrite(br.ReadBytes(pack));
                        Thread.Sleep(sleep);
                    }
                    else
                    {
                        i = maxCount;
                    }
                }
            }
            catch
            {
                return false;
            }
            finally
            {
                br.Close();
                myFile.Close();
            }
        }
        catch
        {
            return false;
        }
        return true;
    }
}Download.ResponseFile(Page.Request, Page.Response, System.IO.Path.GetFileName(e.CommandArgument.ToString()), Server.MapPath(e.CommandArgument.ToString()), 10240000);