C# 实现某几页PDF 分割合并成新的PDF_c# pdf拆分页

using iTextSharp.text;
using iTextSharp.text.pdf;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
 
public partial class PdfItxt : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        int[] pagelist = new int[] { 4, 8 };
        ExtractPages(Server.MapPath("1.pdf"), Server.MapPath("/dd"), pagelist);
    }
 
    public void ExtractPages(string sourcePdfPath, string outputPdfPath, int[] pagelist)
    {
        PdfReader reader = null;
        Document sourceDocument = null;
        PdfCopy pdfCopyProvider = null;
        PdfImportedPage importedPage = null;
        try
        {
            reader = new PdfReader(sourcePdfPath);
            sourceDocument = new Document(reader.GetPageSizeWithRotation(1));
            pdfCopyProvider = new PdfCopy(sourceDocument, new System.IO.FileStream(outputPdfPath + "\\1007.pdf", System.IO.FileMode.Create));
            sourceDocument.Open();
            for (int i = 1; i <= reader.NumberOfPages; i++)
            {
                for (int j = 0; j < pagelist.Length; j++)
                    if (i == pagelist[j])
                    {
                        importedPage = pdfCopyProvider.GetImportedPage(reader, i);
                        pdfCopyProvider.AddPage(importedPage);
                    }
            }
            sourceDocument.Close();
            reader.Close();
        }
        catch (Exception ex) { throw ex; }
    }
 
 
}