asp.net 实现文件下载
方式一:TransmitFile实现下载。将指定的文件直接写入 HTTP 响应输出流,而不在内存中缓冲该文件。
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protected void Button1_Click(object sender, EventArgs e) ...{ /**//* 微软为Response对象提供了一个新的方法TransmitFile来解决使用Response.BinaryWrite下载超过400mb的文件时导致Aspnet_wp.exe进程回收而无法成功下载的问题。 代码如下: */ Response.ContentType = "application/x-zip-compressed"; Response.AddHeader("Content-Disposition", "attachment;filename=CodeShark.zip"); string filename = Server.MapPath("DownLoad/CodeShark.zip"); Response.TransmitFile(filename); }
方式二:WriteFile实现下载,将指定的文件直接写入 HTTP 响应输出流。注意:对大型文件使用此方法时,调用此方法可能导致异常。可以使用此方法的文件大小取决于 Web 服务器的硬件配置。
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protected void Button2_Click(object sender, EventArgs e) ...{ string fileName = "CodeShark.zip";//客户端保存的文件名 string filePath = Server.MapPath("DownLoad/CodeShark.doc");//路径 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(); }
方式三:WriteFile分块下载
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protected void Button3_Click(object sender, EventArgs e) ...{ string fileName = "CodeShark.zip";//客户端保存的文件名 string filePath = Server.MapPath("DownLoad/CodeShark.zip");//路径 System.IO.FileInfo fileInfo = new System.IO.FileInfo(filePath); if (fileInfo.Exists == true) ...{ const long ChunkSize = 102400;//100K 每次读取文件,只读取100K,这样可以缓解服务器的压力 byte[] buffer = new byte[ChunkSize]; Response.Clear(); System.IO.FileStream iStream = System.IO.File.OpenRead(filePath); long dataLengthToRead = iStream.Length;//获取下载的文件总大小 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));//读取的大小 Response.OutputStream.Write(buffer, 0, lengthRead); Response.Flush(); dataLengthToRead = dataLengthToRead - lengthRead; } Response.Close(); } }
方式四:流方式下载
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string fileName = "CodeShark.zip";//客户端保存的文件名 string filePath = Server.MapPath("DownLoad/CodeShark.zip");//路径 //以字符流的形式下载文件 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"; //通知浏览器下载文件而不是打开 Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8)); Response.BinaryWrite(bytes); Response.Flush(); Response.End();