UWP StorageFile StorageFolder StorageFileHelper

                  //获取表示指定文件系统路径中的文件夹的 StorageFolder。
                    StorageFolder folder1 = await StorageFolder.GetFolderFromPathAsync(@"H:\myfolder\");

                    //获取 StorageFile 对象以代表指定路径中的文件。
                    StorageFile file1 = await StorageFile.GetFileFromPathAsync(@"H:\myfolder\myfile.txt");

                    //文件命名是否有效
                    bool isValid =  StorageFileHelper.IsFileNameValid(@"myfile234.txt");

                    // 查询文件夹下所有 .txt 文件(递归子目录/子目录/....)
                    QueryOptions queryOptions = new QueryOptions();
                    queryOptions.FileTypeFilter.Add(".txt");
                    queryOptions.FolderDepth = FolderDepth.Deep;//递归子目录
                    StorageFileQueryResult queryResult = folder1.CreateFileQueryWithOptions(queryOptions);
                    IReadOnlyList<StorageFile> queryFileList = await queryResult.GetFilesAsync();