C# iTextSharp 带书签合并多个PDF

private void MergePdfFilesWithBookMark(string[] sourcePdfs, string outputPdf)
{
PdfReader reader = null;
Document document = new Document();
PdfImportedPage page = null;
PdfCopy pdfCpy = null;
int n = 0;
int totalPages = 0;
int page_offset = 0;
List<Dictionary<string, object>> bookmarks = new List<Dictionary<string, object>>();
IList<Dictionary<string, object>> tempBookmarks;
for (int i = 0; i <= sourcePdfs.GetUpperBound(0); i++)
{
reader = new PdfReader(sourcePdfs[i]);
reader.ConsolidateNamedDestinations();
n = reader.NumberOfPages;
tempBookmarks = SimpleBookmark.GetBookmark(reader);

if (i == 0)
{
document = new iTextSharp.text.Document(reader.GetPageSizeWithRotation(1));
pdfCpy = new PdfCopy(document, new FileStream(outputPdf, FileMode.Create));
document.Open();
SimpleBookmark.ShiftPageNumbers(tempBookmarks, page_offset, null);
page_offset += n;
if (tempBookmarks != null)
bookmarks.AddRange(tempBookmarks);
//  MessageBox.Show(n.ToString());
totalPages = n;
}
else
{
SimpleBookmark.ShiftPageNumbers(tempBookmarks, page_offset, null);
if (tempBookmarks != null)
bookmarks.AddRange(tempBookmarks);

page_offset += n;
totalPages += n;
}

for (int j = 1; j <= n; j++)
{
page = pdfCpy.GetImportedPage(reader, j);
pdfCpy.AddPage(page);

}
reader.Close();

}
pdfCpy.Outlines = bookmarks;
document.Close();
}