asp.net下載檔案方法

/*
* 輸入參數
* _Request: Page.Request 對象
* _Response: Page.Response 對象
* _fileName: 下載檔案名稱
* _fullPath: 帶檔案名稱下載路徑
* _speed 每秒允許下載的位元組數
* 返回是否成功
*/

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(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(pack));                        Thread.Sleep(sleep);                    }else {                            i=maxCount;                    }                }            }catch {                    return false;            }finally {                    br.Close();                myFile.Close();            }        }catch {                return false;        }        return true; }

調用例
Page.Response.Clear(); bool success = ResponseFile(Page.Request, Page.Response, "filename", @"C:\download.date", 1024000); if(!success)            Response.Write("下載檔案出錯！"); Page.Response.End();
 
如何通過ASP.NET來下載檔案，這個問題我們經常遇到，把常用的方法總結到一起，學習學習。當我們要讓使用者下載一個檔案，最簡單的方式是通過Response.Redirect指令： 
Response.Redirect("test.doc") 

您可以把上面這行指令放在Button的Click事件當中，當使用者點擊按鈕之後，網頁就會被轉址到該word檔，造成下載的效果。
但是這樣的下載有幾個問題：
1、無法下載不存在的檔案：例如，我們若是想把程式動態(臨時)產生的文字，當作一個檔案下載的時候(也就是該檔案其實原先並不是真的存在，而是動態產生的)，就無法下載。
2、無法下載儲存於資料庫中的檔案：這是類似的問題，該檔案並沒有真的存在，只是被存放在資料庫中的某個位置(某筆記錄中的某個欄位)的時候，就無法下載。
3、無法下載不存在於Web檔案夾中的檔案：檔案確實存在，但該檔案夾並不是可以分享出來的Web檔案夾，例如，該檔案的位置在C:\winnt，您總不會想要把該檔案夾當作Web檔案夾吧?這時候，由於您無法使用Redirect指向該位置，所以無法下載。
4、下載檔案後，原本的頁面將會消失。
典型的狀況是，我們要讓使用者下載一個.txt檔案或是.csv格式的Excel檔案，但是...
1、這個檔案可能是通過ASP.NET程式動態產生的，而不是確實存在於Server端的檔案；
2、或是它雖然存在於伺服器端的某個實體位置，但我們並不想暴露這個位置(如果這個位置公開，很可能沒有許可權的使用者也可以在網址欄上輸入URL直接取得!!!)
3、或是這個位置並不在網站虛擬路徑所在的檔案夾中。(例如C:\Windows\System32...)

    //TransmitFile實現下載 
     protected void Button1_Click(object sender, EventArgs e)
     {
         /* 
         微軟為Response對象提供了一個新的方法TransmitFile來解決使用Response.BinaryWrite 
         下載超過400mb的檔案時導致Aspnet_wp.exe進程回收而無法成功下載的問題。 
         代碼如下： 
         */ 
         Response.ContentType = "application/x-zip-compressed";
         Response.AddHeader("Content-Disposition", "attachment;filename=z.zip");
         string filename = Server.MapPath("DownLoad/z.zip");
         Response.TransmitFile(filename);
     }
     //WriteFile實現下載 
     protected void Button2_Click(object sender, EventArgs e)
     {
         /* 
         using System.IO;
         */
         string fileName = "asd.txt";//用戶端儲存的檔案名稱 
         string filePath = Server.MapPath("DownLoad/aaa.txt");//路徑
         FileInfo fileInfo = new FileInfo(filePath);
         Response.Clear();
         Response.ClearContent();
         Response.ClearHeaders();
         Response.AddHeader("Content-Disposition", "attachment;filename=" + fileName);
         Response.AddHeader("Content-Length", fileInfo.Length.ToString());
         Response.AddHeader("Content-Transfer-Encoding", "binary");
         Response.ContentType = "application/octet-stream";
         Response.ContentEncoding = System.Text.Encoding.GetEncoding("gb2312");
         Response.WriteFile(fileInfo.FullName);
         Response.Flush();
         Response.End();
     }
     //WriteFile分塊下載 
     protected void Button3_Click(object sender, EventArgs e)
     {
         string fileName = "aaa.txt";//用戶端儲存的檔案名稱 
         string filePath = Server.MapPath("DownLoad/aaa.txt");//路徑
         System.IO.FileInfo fileInfo = new System.IO.FileInfo(filePath);
         if (fileInfo.Exists == true)
         {
             const long ChunkSize = 102400;//100K 每次讀取檔案，唯讀取100K，這樣可以緩解伺服器的壓力 
             byte[] buffer = new byte[ChunkSize];
             Response.Clear();
             System.IO.FileStream iStream = System.IO.File.OpenRead(filePath);
             long dataLengthToRead = iStream.Length;//擷取下載的檔案總大小 
             Response.ContentType = "application/octet-stream";
             Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(fileName));
             while (dataLengthToRead > 0 && Response.IsClientConnected)
             {
                 int lengthRead = iStream.Read(buffer, 0, Convert.ToInt32(ChunkSize));//讀取的大小 
                 Response.OutputStream.Write(buffer, 0, lengthRead);
                 Response.Flush();
                 dataLengthToRead = dataLengthToRead - lengthRead;
             }
             Response.Close();
         }
     }
     //流方式下載 
     protected void Button4_Click(object sender, EventArgs e)
     {
         string fileName = "aaa.txt";//用戶端儲存的檔案名稱 
         string filePath = Server.MapPath("DownLoad/aaa.txt");//路徑
         //以字元流的形式下載檔案 
         FileStream fs = new FileStream(filePath, FileMode.Open);
         byte[] bytes = new byte[(int)fs.Length];
         fs.Read(bytes, 0, bytes.Length);
         fs.Close();
         Response.ContentType = "application/octet-stream";
         //通知瀏覽器下載檔案而不是開啟 
         Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8));
         Response.BinaryWrite(bytes);
         Response.Flush();
         Response.End();
     }
//----------------------------------------------------------

public void DownloadFile( System.Web.UI.Page WebForm,String FileNameWhenUserDownload ,String FileBody )
{
　　WebForm.Response.ClearHeaders();
　　WebForm.Response.Clear();
　　WebForm.Response.Expires = 0;
　　WebForm.Response.Buffer = true;
　　WebForm.Response.AddHeader("Accept-Language", "zh-tw");
　　//'檔案名稱
　　WebForm.Response.AddHeader("content-disposition", "attachment; filename='"+System.Web.HttpUtility.UrlEncode(FileNameWhenUserDownload, System.Text.Encoding.UTF8)+"'");
　　WebForm.Response.ContentType = "Application/octet-stream";
　　//'檔案內容
　　WebForm.Response.Write(FileBody);//-----------
     WebForm.Response.End();
}
//上面這段代碼是下載一個動態產生的文字檔，若這個檔案已經存在於伺服器端的實體路徑，則可以通過下面的函數：
public void DownloadFileByFilePath( System.Web.UI.Page WebForm,String FileNameWhenUserDownload ,String FilePath )
{
　　WebForm.Response.ClearHeaders();
　　WebForm.Response.Clear();
　　WebForm.Response.Expires = 0;
     WebForm.Response.Buffer = true;
　　WebForm.Response.AddHeader("Accept-Language", "zh-tw");
　　//檔案名稱
　　WebForm.Response.AddHeader("content-disposition", "attachment; filename='" + System.Web.HttpUtility.UrlEncode(FileNameWhenUserDownload, System.Text.Encoding.UTF8) +"'" );
　　WebForm.Response.ContentType = "Application/octet-stream";
　　//檔案內容
　　WebForm.Response.Write(System.IO.File.ReadAllBytes(FilePath));//---------
　　WebForm.Response.End();
}
 
 
 
下面是更詳細的ContentType
'ez' => 'application/andrew-inset', 
'hqx' => 'application/mac-binhex40', 
'cpt' => 'application/mac-compactpro', 
'doc' => 'application/msword', 
'bin' => 'application/octet-stream', 
'dms' => 'application/octet-stream', 
'lha' => 'application/octet-stream', 
'lzh' => 'application/octet-stream', 
'exe' => 'application/octet-stream', 
'class' => 'application/octet-stream', 
'so' => 'application/octet-stream', 
'dll' => 'application/octet-stream', 
'oda' => 'application/oda', 
'pdf' => 'application/pdf', 
'ai' => 'application/postscript', 
'eps' => 'application/postscript', 
'ps' => 'application/postscript', 
'smi' => 'application/smil', 
'smil' => 'application/smil', 
'mif' => 'application/vnd.mif', 
'xls' => 'application/vnd.ms-excel', 
'ppt' => 'application/vnd.ms-powerpoint', 
'wbxml' => 'application/vnd.wap.wbxml', 
'wmlc' => 'application/vnd.wap.wmlc', 
'wmlsc' => 'application/vnd.wap.wmlscriptc', 
'bcpio' => 'application/x-bcpio', 
'vcd' => 'application/x-cdlink', 
'pgn' => 'application/x-chess-pgn', 
'cpio' => 'application/x-cpio', 
'csh' => 'application/x-csh', 
'dcr' => 'application/x-director', 
'dir' => 'application/x-director', 
'dxr' => 'application/x-director', 
'dvi' => 'application/x-dvi', 
'spl' => 'application/x-futuresplash', 
'gtar' => 'application/x-gtar', 
'hdf' => 'application/x-hdf', 
'js' => 'application/x-javascript', 
'skp' => 'application/x-koan', 
'skd' => 'application/x-koan', 
'skt' => 'application/x-koan', 
'skm' => 'application/x-koan', 
'latex' => 'application/x-latex', 
'nc' => 'application/x-netcdf', 
'cdf' => 'application/x-netcdf', 
'sh' => 'application/x-sh', 
'shar' => 'application/x-shar', 
'swf' => 'application/x-shockwave-flash', 
'sit' => 'application/x-stuffit', 
'sv4cpio' => 'application/x-sv4cpio', 
'sv4crc' => 'application/x-sv4crc', 
'tar' => 'application/x-tar', 
'tcl' => 'application/x-tcl', 
'tex' => 'application/x-tex', 
'texinfo' => 'application/x-texinfo', 
'texi' => 'application/x-texinfo', 
't' => 'application/x-troff', 
'tr' => 'application/x-troff', 
'roff' => 'application/x-troff', 
'man' => 'application/x-troff-man', 
'me' => 'application/x-troff-me', 
'ms' => 'application/x-troff-ms', 
'ustar' => 'application/x-ustar', 
'src' => 'application/x-wais-source', 
'xhtml' => 'application/xhtml+xml', 
'xht' => 'application/xhtml+xml', 
'zip' => 'application/zip', 
'au' => 'audio/basic', 
'snd' => 'audio/basic', 
'mid' => 'audio/midi', 
'midi' => 'audio/midi', 
'kar' => 'audio/midi', 
'mpga' => 'audio/mpeg', 
'mp2' => 'audio/mpeg', 
'mp3' => 'audio/mpeg', 
'aif' => 'audio/x-aiff', 
'aiff' => 'audio/x-aiff', 
'aifc' => 'audio/x-aiff', 
'm3u' => 'audio/x-mpegurl', 
'ram' => 'audio/x-pn-realaudio', 
'rm' => 'audio/x-pn-realaudio', 
'rpm' => 'audio/x-pn-realaudio-plugin', 
'ra' => 'audio/x-realaudio', 
'wav' => 'audio/x-wav', 
'pdb' => 'chemical/x-pdb', 
'xyz' => 'chemical/x-xyz', 
'bmp' => 'image/bmp', 
'gif' => 'image/gif', 
'ief' => 'image/ief', 
'jpeg' => 'image/jpeg', 
'jpg' => 'image/jpeg', 
'jpe' => 'image/jpeg', 
'png' => 'image/png', 
'tiff' => 'image/tiff', 
'tif' => 'image/tiff', 
'djvu' => 'image/vnd.djvu', 
'djv' => 'image/vnd.djvu', 
'wbmp' => 'image/vnd.wap.wbmp', 
'ras' => 'image/x-cmu-raster', 
'pnm' => 'image/x-portable-anymap', 
'pbm' => 'image/x-portable-bitmap', 
'pgm' => 'image/x-portable-graymap', 
'ppm' => 'image/x-portable-pixmap', 
'rgb' => 'image/x-rgb', 
'xbm' => 'image/x-xbitmap', 
'xpm' => 'image/x-xpixmap', 
'xwd' => 'image/x-xwindowdump', 
'igs' => 'model/iges', 
'iges' => 'model/iges', 
'msh' => 'model/mesh', 
'mesh' => 'model/mesh', 
'silo' => 'model/mesh', 
'wrl' => 'model/vrml', 
'vrml' => 'model/vrml', 
'css' => 'text/css', 
'html' => 'text/html', 
'htm' => 'text/html', 
'asc' => 'text/plain', 
'txt' => 'text/plain', 
'rtx' => 'text/richtext', 
'rtf' => 'text/rtf', 
'sgml' => 'text/sgml', 
'sgm' => 'text/sgml', 
'tsv' => 'text/tab-separated-values', 
'wml' => 'text/vnd.wap.wml', 
'wmls' => 'text/vnd.wap.wmlscript', 
'etx' => 'text/x-setext', 
'xsl' => 'text/xml', 
'xml' => 'text/xml', 
'mpeg' => 'video/mpeg', 
'mpg' => 'video/mpeg', 
'mpe' => 'video/mpeg', 
'qt' => 'video/quicktime', 
'mov' => 'video/quicktime', 
'mxu' => 'video/vnd.mpegurl', 
'avi' => 'video/x-msvideo', 
'movie' => 'video/x-sgi-movie', 
'ice' => 'x-conference/x-cooltalk'
 
 
 
轉載:  http://www.cnblogs.com/kingkoo/archive/2009/08/08/1541593.html