using iText.Kernel.Pdf; namespace DS.Module.Core.Utils { /// /// PDF处理工具类 /// public static class PDFUtil { public static async void AddStrampAsync(this Stream stream) { ArgumentNullException.ThrowIfNull(stream, nameof(stream)); if (!stream.CanRead) throw new ArgumentException("流不支持读取", nameof(stream)); var pdfStream = stream; if (!stream.CanWrite) { pdfStream = new MemoryStream(); await stream.CopyToAsync(pdfStream); } var pdfReader = new PdfReader(stream); } } }