public Tuple <Stream, string, string> CreateExcel()
{
var addrUrl = NPOIExcelHelper.ExportTest();
string fileExt = Path.GetExtension(addrUrl);
//获取文件的ContentType
var provider = new FileExtensionContentTypeProvider();
var contentType = provider.Mappings[fileExt];
addrUrl = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, addrUrl);
var stream = new FileStream(addrUrl, FileMode.Open);
return(new Tuple <Stream, string, string>(stream, Path.GetFileName(addrUrl), contentType));
}