asp.net下载文件几种方式

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

//WriteFile实现下载
protected void 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();
}

//WriteFile分块下载
protected void 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)
    {
        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.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 = 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();

}