C# 文件下载四方法

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();    }}