C# 判断服务器上文件是否存在

var path = " FramePath" ;
var filePath = Server.MapPath(path);
if (System.IO.File.Exists(filePath))
{
var fileName = Path.GetFileName(filePath);
FileInfo info = new FileInfo(filePath);
Response.Clear();
Response.ClearHeaders();
Response.Buffer = false;
Response.ContentType = "application/octet-stream";
Response.AppendHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(FrameName + ".zip", System.Text.Encoding.UTF8).Replace("+", "%20"));
Response.AppendHeader("Content-Length", info.Length.ToString());
Response.WriteFile(filePath);
Response.Flush();
Response.End();
return new EmptyResult();
}