PDF 文件操作 PdfHelper

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using iTextSharp.text;
using iTextSharp.text.pdf;

namespace MEAS.Common
{
    public class PdfHelper
    {
        //定义一个用于保存静态变量的实例
        private static PdfHelper instance = null;
        //定义一个保证线程同步的标识
        private static readonly object locker = new object();
        //构造函数为私有，使外界不能创建该类的实例
        private PdfHelper() { }
        public static PdfHelper Instance
        {
            get
            {
                if (instance == null)
                {
                    lock (locker)
                    {
                        if (instance == null) instance = new PdfHelper();
                    }
                }
                return instance;
            }
        }

        /// <summary>
        /// 合并PDF文件
        /// </summary>
        /// <param name="fileList">需要合并的PDF集合</param>
        /// <param name="outMergeFile">合并后文件路径</param>
        public string MergePDFFiles(string[] fileList, string mergeFile)
        {
            try
            {
                //PdfDocument
                Document document = new Document();
                PdfCopy pdfCopy = new PdfCopy(document, new FileStream(mergeFile, FileMode.Create));
                //PdfWriter writer = PdfWriter.GetInstance(document, new FileStream(mergeFile, FileMode.Create));
                document.Open();
                //PdfContentByte cb = writer.DirectContent;
                //PdfImportedPage newPage;

                for (int i = 0; i < fileList.Length; i++)
                {
                    PdfReader reader = new PdfReader(fileList[i]);
                    int iPageNum = reader.NumberOfPages;
                    for (int j = 1; j <= iPageNum; j++)
                    {

                        document.NewPage();

                        //newPage.Width = //reader.
                        PdfImportedPage newPage = pdfCopy.GetImportedPage(reader, j);
                        pdfCopy.AddPage(newPage);
                        //cb.AddTemplate(newPage, 0, 0);
                    }
                    reader.Close();
                }
                document.Close();
            }
            catch (Exception)
            {

                throw;
            }

            return mergeFile;
        }

        /// <summary>
        /// 合并PDF文件(生成A4大小的页面)
        /// </summary>
        /// <param name="fileList">需要合并的PDF集合</param>
        /// <param name="outMergeFile">合并后文件路径</param>
        public string MergePDFFilesA4(string[] fileList, string mergeFile)
        {
            PdfReader reader;            
            Document document = new Document();
            PdfWriter writer = PdfWriter.GetInstance(document, new FileStream(mergeFile, FileMode.Create));
            document.Open();
            PdfContentByte cb = writer.DirectContent;
            PdfImportedPage newPage;            
            for (int i = 0; i < fileList.Length; i++)
            {
                reader = new PdfReader(fileList[i]);
                int iPageNum = reader.NumberOfPages;
                for (int j = 1; j <= iPageNum; j++)
                {
                    document.NewPage();
                    newPage = writer.GetImportedPage(reader, j);
                    cb.AddTemplate(newPage, 0, 0);
                }
            }
            document.Close();

            return mergeFile;
        }

        ///直接删除指定目录下的所有文件及文件夹(保留目录)
        /// </summary>
        /// <param name="strPath">文件夹路径</param>
        /// <returns>执行结果</returns>
        public  void DeleteDir(string file)
        {
            try
            {
                //去除文件夹和子文件的只读属性
                //去除文件夹的只读属性
                System.IO.DirectoryInfo fileInfo = new DirectoryInfo(file);
                fileInfo.Attributes = FileAttributes.Normal & FileAttributes.Directory;
                //去除文件的只读属性
                System.IO.File.SetAttributes(file, System.IO.FileAttributes.Normal);
                //判断文件夹是否还存在
                if (Directory.Exists(file))
                {
                    foreach (string f in Directory.GetFileSystemEntries(file))
                    {
                        if (File.Exists(f))
                        {
                            //如果有子文件删除文件
                            File.Delete(f);
                            Console.WriteLine(f);
                        }
                        else DeleteDir(f); //循环递归删除子文件夹
                    }

                    //删除空文件夹
                    Directory.Delete(file);
                }
            }
            catch (Exception) // 异常处理
            {
                //throw;
                return;//异常不删除，
                //Console.WriteLine(ex.Message.ToString());// 异常信息
            }
        }


    }
}