Question

我有LiveData使用ViewModel，其中包含Service，应该从前景LiveData进行修改。

我需要的是：

从Activity观察到Service，因此当从MutableLiveData修改后，会更新用户界面。要使其工作，应以某种方式使用LiveData。

我应该将Room存储在_, encoded_img = cv2.imencode('.jpg', img, [ int( cv2.IMWRITE_JPEG_QUALITY ), 95 ] )数据库中，还是针对此问题提供更优雅的解决方案？
如果使用Room是一个解决方案，如何存储和更新单一且唯一的实体？

Answer 1

根据推荐的Android架构，您应该有一个Repository，这只是一个负责向ViewModel提供数据的类，存储库从Room database获取数据并提示服务刷新进入数据库。从RoomDB获取的数据是实时数据，一旦被服务更新，其观察者就会被解雇。 Android architecture components

public class MovieRepository {

    private static final String language = "en-US";
    private static final String sortBy = "popularity.desc";
    private static final String includeAdult = "false";
    private static final String includeVideo = "false";
    private static final String page = "1";

    Resources mResources;

    MovieDatabase mMovieDatabase;
    MoviesInterfaceImpl mMoviesInterface;
    MoviesWatchApplication mMoviesWatchApplication;


    public MovieRepository(MovieDatabase movieDatabase,
                           MoviesInterfaceImpl moviesInterface,
                           MoviesWatchApplication moviesWatchApplication)  {

        mMovieDatabase = movieDatabase;
        mMoviesInterface = moviesInterface;
        mMoviesWatchApplication = moviesWatchApplication;
    }

    public LiveData<List<Movie>> getMovies() {
        mResources = mMoviesWatchApplication.getApplicationContext().getResources();
        refreshMovies();



        LiveData<List<Movie> > movies = mMovieDatabase.movieDao().getMovies();
        return movies;
    }

    private void refreshMovies () {
        mMoviesInterface.discoverMovies(
                mResources.getString(R.string.api_key),
                language, sortBy, includeAdult, includeVideo , page
        ).enqueue(new Callback<DiscoverResponse>() {

            @RequiresApi(api = Build.VERSION_CODES.N)
            @Override
            public void onResponse(Call<DiscoverResponse> call, Response<DiscoverResponse> response) {
                if(response.code() == 200) {
                    List<Movie> movieList = new ArrayList<>();

                    response.body().getResults().forEach((result) -> {
                        Movie movie = new Movie(result);
                        movieList.add(movie);
                    });

                    mMovieDatabase.movieDao().addMovies(movieList);
                }
            }

            @Override
            public void onFailure(Call<DiscoverResponse> call, Throwable t) {

            }
        });
    }
}

从服务更新LiveData

1 个答案: