用内存流切换文件流。
MemoryStream memStream = new MemoryStream();PdfWriter wri = PdfWriter.GetInstance(doc, memStream);...return memStream.ToArray();

用内存流切换文件流。
MemoryStream memStream = new MemoryStream();PdfWriter wri = PdfWriter.GetInstance(doc, memStream);...return memStream.ToArray();