.net文件下载

public void downloadfile(string s_fileName)
{
try
{
HttpContext.Current.Response.ContentType = "application/ms-download";
string s_path = HttpContext.Current.Server.MapPath("~/project/ComFile/" + s_fileName);
System.IO.FileInfo file = new System.IO.FileInfo(s_path);
if (file.Exists)
{
HttpContext.Current.Response.Clear();
HttpContext.Current.Response.AddHeader("Content-Type", "application/octet-stream");
HttpContext.Current.Response.Charset = "utf-8";
HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment;filename=" + System.Web.HttpUtility.UrlEncode(file.Name, System.Text.Encoding.UTF8));
HttpContext.Current.Response.AddHeader("Content-Length", file.Length.ToString());
HttpContext.Current.Response.WriteFile(file.FullName);
HttpContext.Current.Response.Flush();
HttpContext.Current.Response.Clear();
HttpContext.Current.Response.End();
}
else
{
HttpContext.Current.Response.Write("<script language='javascript' type='text/javascript'>alert('文件不存在');history.back();</script>");

}
}
catch
{
HttpContext.Current.Response.Write("<script language='javascript' type='text/javascript'>alert('文件不存在');history.back();</script>");
}

finall

{

HttpContext.Current.Response.End();

}

}