asp.net中实现文件下载功能

// 1 TransmitFile实现下载
    protectedvoid 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=z.zip");
        string filename= Server.MapPath("DownLoad/aaa.zip");//绝对路径为：string path=@"D:\1.jpg";
         Response.TransmitFile(filename);
     }

    //2 WriteFile实现下载
    protectedvoid Button2_Click(object sender, EventArgs e)
     {
        /*
          using System.IO;
         
         */

        string fileName="aaa.zip";//客户端保存的文件名
        string filePath=Server.MapPath("DownLoad/aaa.zip");//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();
     }

    //3 WriteFile分块下载
    protectedvoid Button3_Click(object sender, EventArgs e)
     {

        string fileName="aaa.zip";//客户端保存的文件名
        string filePath= Server.MapPath("DownLoad/aaa.zip");//路径

         System.IO.FileInfo fileInfo =new System.IO.FileInfo(filePath);

        if (fileInfo.Exists==true)
         {
            constlong 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=newbyte[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();
         }
     }

    // 4  流方式下载
    protectedvoid Button4_Click(object sender, EventArgs e)
     {
        string fileName="aaa.zip";//客户端保存的文件名
        string filePath= Server.MapPath("DownLoad/aaa.zip");//路径

        //以字符流的形式下载文件
         FileStream fs =new FileStream(filePath, FileMode.Open);
        byte[] bytes=newbyte[(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();

     }