1，Http 协议中有专门的指令来告知浏览器, 本次响应的是一个需要下载的文件. 格式如下:
Content-Disposition: attachment;filename=filename.ext以上指令即标记此次响应流是附件,且附件文件名为 filename.ext注意：(1): 中文文件名需要进行URLEncode编码, 否则在IE 6 下会提示是”无法识别的文件”.但经实际测试,在Chrome下不进行URLEncode编码, 也能正常显示.(2): 文件名不能有空格, 否则也会被认为是”无法识别的文件”.(3): [ASP.Net中] 向响应流中添加该指令必须使用 response.AddHeader() 函数; 使用response.Header.Add() 则会报错.下面是一个实现下载文件功能的函数：////// 使用微软的TransmitFile下载文件 /// /// 服务器相对路径 public void TransmitFile(string filePath) { try { filePath = Server.MapPath(filePath); if (File.Exists(filePath)) { FileInfo info = new FileInfo(filePath); long fileSize = info.Length; HttpContext.Current.Response.Clear(); //指定Http Mime格式为压缩包 HttpContext.Current.Response.ContentType = "application/x-zip-compressed"; // Http 协议中有专门的指令来告知浏览器, 本次响应的是一个需要下载的文件. 格式如下: // Content-Disposition: attachment;filename=filename.txt HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment;filename=" + Server.UrlEncode(info.FullName)); //不指明Content-Length用Flush的话不会显示下载进度 HttpContext.Current.Response.AddHeader("Content-Length", fileSize.ToString()); HttpContext.Current.Response.TransmitFile(filePath, 0, fileSize); HttpContext.Current.Response.Flush(); } } catch { } finally { HttpContext.Current.Response.Close(); } }
2 下面是使用WriteFile实现下载
////// 使用WriteFile下载文件 /// /// 相对路径 public void WriteFile(string filePath) { try { filePath = Server.MapPath(filePath); if (File.Exists(filePath)) { FileInfo info = new FileInfo(filePath); long fileSize = info.Length; HttpContext.Current.Response.Clear(); HttpContext.Current.Response.ContentType = "application/octet-stream"; HttpContext.Current.Response.AddHeader("Content-Disposition", "attachement;filename=" + Server.UrlEncode(info.FullName)); //指定文件大小 HttpContext.Current.Response.AddHeader("Content-Length", fileSize.ToString()); HttpContext.Current.Response.WriteFile(filePath, 0, fileSize); HttpContext.Current.Response.Flush(); } } catch { } finally { HttpContext.Current.Response.Close(); } }
3，下面是分块实现下载
////// 使用OutputStream.Write分块下载文件 /// /// public void WriteFileBlock(string filePath) { filePath = Server.MapPath(filePath); if (!File.Exists(filePath)) { return; } FileInfo info = new FileInfo(filePath); //指定块大小 long chunkSize = 4096; //建立一个4K的缓冲区 byte[] buffer = new byte[chunkSize]; //剩余的字节数 long dataToRead = 0; FileStream stream = null; try { //打开文件 stream = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.Read); dataToRead = stream.Length; //添加Http头 HttpContext.Current.Response.ContentType = "application/octet-stream"; HttpContext.Current.Response.AddHeader("Content-Disposition", "attachement;filename=" + Server.UrlEncode(info.FullName)); HttpContext.Current.Response.AddHeader("Content-Length", dataToRead.ToString()); while (dataToRead > 0) { if (HttpContext.Current.Response.IsClientConnected) { int length = stream.Read(buffer, 0, Convert.ToInt32(chunkSize)); HttpContext.Current.Response.OutputStream.Write(buffer, 0, length); HttpContext.Current.Response.Flush(); HttpContext.Current.Response.Clear(); dataToRead -= length; } else { //防止client失去连接 dataToRead = -1; } } } catch (Exception ex) { HttpContext.Current.Response.Write("Error:" + ex.Message); } finally { if (stream != null) { stream.Close(); } HttpContext.Current.Response.Close(); } }
转: