asp.net下载文件的四种方法

using System;using System.Data;using System.Configuration;using System.Web;using System.Web.Security;using System.Web.UI;using System.Web.UI.WebControls;using System.Web.UI.WebControls.WebParts;using System.Web.UI.HtmlControls;using System.IO;public partial class _Default : System.Web.UI.Page{protected void Page_Load(object sender, EventArgs e){}//TransmitFile实现下载protected void Button1_Click(object sender, EventArgs e){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实现下载protected void Button2_Click(object sender, EventArgs e){string fileName ="asd.txt";//客户端保存的文件名string filePath=Server.MapPath("DownLoad/aaa.txt");//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();}//WriteFile分块下载protected void Button3_Click(object sender, EventArgs e){string fileName = "aaa.txt";//客户端保存的文件名string filePath = Server.MapPath("DownLoad/aaa.txt");//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();}}//流方式下载protected void Button4_Click(object sender, EventArgs e){string fileName = "aaa.txt";//客户端保存的文件名string filePath = Server.MapPath("DownLoad/aaa.txt");//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();}}