protected void Button_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=z.zip");string filename = Server.MapPath("DownLoad/aaa.zip");//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。
        Response.TransmitFile(filename);}

    protected void Button_Click(object sender, EventArgs e){/* using System.IO; */string fileName = "aaa.zip";//服务端保存的文件名string filePath = Server.MapPath("DownLoad/aaa.zip");//路径
System.IO.FileInfo fileInfo = new System.IO.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");//将指定文件的内容作为文件块直接写入 HTTP 响应输出流。
        Response.WriteFile(fileInfo.FullName);Response.Flush();Response.End();}

    protected void Button_Click(object sender, EventArgs e){string fileName = "aaa.zip";//服务端保存的文件名string filePath = Server.MapPath("DownLoad/aaa.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){//从流中读取字节块并将该数据写入给定缓冲区中//返回结果:读入缓冲区中的总字节数。//如果当前的字节数没有所请求那么多，则总字节数可能小于所请求的字节数；如果已到达流的末尾，则为零。int lengthRead = iStream.Read(buffer, 0, Convert.ToInt32(ChunkSize));//读取的大小//当在派生类中重写时，向当前流中写入字节序列，并将此流中的当前位置提升写入的字节数。Response.OutputStream.Write(buffer, 0, lengthRead);Response.Flush();dataLengthToRead = dataLengthToRead - lengthRead;}Response.Close();}}

    protected void Button4_Click(object sender, EventArgs e){string fileName = "aaa.zip";//服务端保存的文件名string filePath = Server.MapPath("DownLoad/aaa.zip");//路径//以字符流的形式下载文件System.IO.FileStream fs = new System.IO.FileStream(filePath, System.IO.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));//将一个二进制字符串写入 HTTP 输出流
        Response.BinaryWrite(bytes);Response.Flush();Response.End();}