window store app 附件读取

   public static async Task<bool> DisplayApplicationPicker(string folderName, string fileName)
         {
             // Path to the file in the app package to launch  

             MessageDialog message = null;
             StorageFolder storageFolder = null;
             StorageFile GetStorageFile = null;

             IReadOnlyList<StorageFolder> storageFolders;

             bool isExist = false;
             try
             {

                 try
                 {

                     //在指定的应用程序文件夹下查找指定的文件
                     storageFolder = ApplicationData.Current.LocalFolder;
                     storageFolders = await storageFolder.GetFoldersAsync();
                     isExist = storageFolders.Any(folder => folder.Name == folderName);
                     if (isExist)
                     {
                         storageFolder = await ApplicationData.Current.LocalFolder.GetFolderAsync(folderName);

                     }
                     else
                     {
                         storageFolder = await ApplicationData.Current.LocalFolder.CreateFolderAsync(folderName);
                     }

                 }
                 catch (System.IO.FileNotFoundException ex)
                 {
                     message = new MessageDialog(ex.Message);
                     message.ShowAsync();
                 }
                 //判断是否有该文件
                 try
                 {
                     //在指定的应用程序文件夹下查找指定的文件
                     if (isExist)
                     {
                         IReadOnlyList<StorageFile> files = await storageFolder.GetFilesAsync();
                         bool isExistfile = files.Any(file => file.Name == fileName);
                         if (!isExistfile)
                         {
                             message = new MessageDialog("Didn't find the specified file");
                             message.ShowAsync();
                             //todo: Written to the file Method
                         }
                         else
                         {
                             GetStorageFile = await storageFolder.GetFileAsync(fileName);
                         }

                     }

                 }
                 catch (System.IO.FileNotFoundException ex)
                 {
                     message = new MessageDialog(ex.Message);
                     message.ShowAsync();
                 }

                 if (GetStorageFile != null)
                 {
                     // Set the option to show the picker
                     var options = new Windows.System.LauncherOptions();
                     options.DisplayApplicationPicker = true;

                     // Launch the retrieved file
                     bool success = await Windows.System.Launcher.LaunchFileAsync(GetStorageFile, options);

                     if (success)
                     {
                         // File launched
                         return true;

                     }
                     else
                     {
                         // File launch failed
                         message = new MessageDialog("Please choose other open way");
                         message.ShowAsync();
                         return false;

                     }
                 }
                 else
                 {
                     message = new MessageDialog( "Didn't find the specified file");
                     message.ShowAsync();
                     return false;
                 }

             }
             catch (Exception ex)
             {
                 message = new MessageDialog(ex.Message);
                 message.ShowAsync();
                 return false;
             }

         }