使用asp.net下载文件

protected void DownloadFile(string fileName)
{
    // 获取文件的绝对路径
    string filePath = Server.MapPath(fileName);

    // 检查文件是否存在
    if (!File.Exists(filePath))
    {
        Response.Write("文件不存在");
        return;
    }

    // 设置响应头
    Response.Clear();
    Response.ContentType = "application/octet-stream";
    Response.AddHeader("Content-Disposition", "attachment; filename=" + Path.GetFileName(filePath));
    Response.AddHeader("Content-Length", new FileInfo(filePath).Length.ToString());

    // 读取文件并写入响应流
    using (FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read))
    {
        byte[] buffer = new byte[1024];
        int bytesRead;
        while ((bytesRead = fs.Read(buffer, 0, buffer.Length)) > 0)
        {
            Response.OutputStream.Write(buffer, 0, bytesRead);
        }
    }

    // 结束响应
    Response.End();
}