本地Mongodb安全(Local Mongodb security)

 每当您使用iTextSharp编写需要创建新文档的内容时，它都不会写入现有文档。 在您的情况下，页面重新排序需要编写，因此您需要创建一个新文档，将页面重新排序然后重新排序。 （当然，您也可以在导入时重新排序它们。） 
 
        var inputFile = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "Test.pdf");
        var output = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "Output.pdf");

        //Bind a reader to our input file
        var reader = new PdfReader(inputFile);

        //Create our output file, nothing special here
        using (FileStream fs = new FileStream(output, FileMode.Create, FileAccess.Write, FileShare.None)) {
            using (Document doc = new Document(reader.GetPageSizeWithRotation(1))) {
                //Use a PdfCopy to duplicate each page
                using (PdfCopy copy = new PdfCopy(doc, fs)) {
                    doc.Open();
                    copy.SetLinearPageMode();
                    for (int i = 1; i <= reader.NumberOfPages; i++) {
                        copy.AddPage(copy.GetImportedPage(reader, i));
                    }
                    //Reorder pages
                    copy.ReorderPages(new int[] { 2, 1 });
                    doc.Close();
                }
            }
        }

Whenever you use iTextSharp to write something you need to create a new document, it will never write to an existing document. In your case, page reordering would require writing so you need create a new document, bring over the pages and then reorder them. (Of course, you could also just reorder them upon import, too.)
 
        var inputFile = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "Test.pdf");
        var output = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "Output.pdf");

        //Bind a reader to our input file
        var reader = new PdfReader(inputFile);

        //Create our output file, nothing special here
        using (FileStream fs = new FileStream(output, FileMode.Create, FileAccess.Write, FileShare.None)) {
            using (Document doc = new Document(reader.GetPageSizeWithRotation(1))) {
                //Use a PdfCopy to duplicate each page
                using (PdfCopy copy = new PdfCopy(doc, fs)) {
                    doc.Open();
                    copy.SetLinearPageMode();
                    for (int i = 1; i <= reader.NumberOfPages; i++) {
                        copy.AddPage(copy.GetImportedPage(reader, i));
                    }
                    //Reorder pages
                    copy.ReorderPages(new int[] { 2, 1 });
                    doc.Close();
                }
            }
        }