word 转换成 pdf

         /// <summary>
        /// 把word文件变成PDF文件（这个是单个word文件变成pdf格式）
        /// </summary>
        /// <param name="sourceFileName">源文件</param>
        /// <param name="targetFileName">目标文件</param>
        /// <returns></returns>
        public bool ExportToPdf(string sourceFileName, string targetFileName)
        {
            docApplication = new Microsoft.Office.Interop.Word.Application();
            try
            {
if (!File.Exists(sourceFileName))
                {
                    _message = "需要转换PDF格式的源文件不存在!";
                    //CommonLibrary.Logger.Trace("当前进度：转换pdf的源word文档不存在！");
                    return false;
                }
                if (File.Exists(targetFileName))
                {
                    File.Delete(targetFileName);
                }
                Word.Document document = null;
                object missing = System.Reflection.Missing.Value;
                object FileName = sourceFileName;
                object readOnly = false;
                object isVisible = false;                
                //doc = ExOffice.OpenDocument(docApplication, fileName, false, false);
                document = docApplication.Documents.Open(ref FileName, ref missing, ref readOnly,
                   ref missing, ref missing, ref missing, ref missing, ref missing,
                   ref missing, ref missing, ref missing, ref isVisible, ref missing,
                   ref missing, ref missing, ref missing);

                string version = document.Application.Version;
                version = version.Substring(0, version.IndexOf('.'));
                if (int.Parse(version) >= 12)//版本号是12或者以上
                {
                    object FixedFormatExtClassPtr = System.Type.Missing;
                    document.ExportAsFixedFormat(targetFileName,
                    Word.WdExportFormat.wdExportFormatPDF,
                    false,
                    Word.WdExportOptimizeFor.wdExportOptimizeForOnScreen,
                    Word.WdExportRange.wdExportAllDocument,
                    0,
                    0,
                    Word.WdExportItem.wdExportDocumentWithMarkup,
                    true,
                    true,
                    Word.WdExportCreateBookmarks.wdExportCreateWordBookmarks,
                    true,
                    true,
                    true,
                    ref FixedFormatExtClassPtr);
                    _message = "转换成功！";
                    return true;

                }
                else
                {
                    _message = "word版本太低，不能转换PDF格式！";
                    return false;
                }

            }
            catch (System.Runtime.InteropServices.COMException exception)
            {
                _message = exception.Message;
                //UE.Library.FrmMessage.Show(exception.Message+"您可能没有安装word转pdf的插件！");
                CommonLibrary.Logger.Trace(exception);
                return false;
            }
            catch (Exception ex)
            {
                //UE.Library.FrmMessage.Show(ex.Message);
                _message = ex.Message;
                CommonLibrary.Logger.Trace(ex);
                return false;
            }
            finally
            {
                if(docApplication!=null)//因为单击取消按钮，此方法还是会执行完，但是此时docApplication已经释放了，所以要加此if
                {
                    if(!hasCancel)
                    {                        
                        ReleaseWordResource();
                    }
                }
            }            
        }