using Spire.Pdf;
using Spire.Pdf.Bookmarks;
using System;
using System.IO;
using System.Text;
namespace ReadBookmark_PDF
{
    class Program
    {
        static void Main(string[] args)
        {
            //实例化PdfDocument类的对象，并加载含有多级书签的PDF文件
            PdfDocument doc = new PdfDocument();
            doc.LoadFromFile("test.pdf");
            //获取文档的书签
            PdfBookmarkCollection bookmarks = doc.Bookmarks;
            //声明一个可变字符串
            StringBuilder stringbuilder = new StringBuilder();
            //获取父书签和子书签
            GetBookmarkTitle(bookmarks, stringbuilder);
            //声明txt文件，并将获得的多级书签写入到文件.txt
            String fileName = "output.txt";
            File.WriteAllText(fileName, stringbuilder.ToString());
        }
        //自定义方法获取书签
        static void GetBookmarkTitle(PdfBookmarkCollection bookmarks, StringBuilder stringbuilder)
        {
            //遍历书签
            if (bookmarks.Count > 0)
            {
                foreach (PdfBookmark parentBookmark in bookmarks)
                {
                    stringbuilder.AppendLine(parentBookmark.Title);
                    //获取书签
                    GetBookmarkTitle(parentBookmark, stringbuilder);
                }
            }
        }
    }
}