网络绑定资源(NetworkBoundResource)仍然是一个有效的方法吗？

网络绑定资源(NetworkBoundResource)仍然是一种有效的方法，它使得在使用网络请求获取数据时，能够更好地处理UI的变化和错误处理。下面是一个示例：

public abstract class NetworkBoundResource<ResultType, RequestType> {
    protected LiveData<Resource<ResultType>> result = new MediatorLiveData<>();

    @MainThread
    protected NetworkBoundResource() {
        result.setValue(Resource.loading(null));
        final LiveData<ResultType> dbSource = loadFromDb();

        result.addSource(dbSource, data -> {
            result.removeSource(dbSource);
            if (shouldFetch(data)) {
                fetchFromNetwork(dbSource);
            } else {
                result.addSource(dbSource,
                        newData -> result.setValue(Resource.success(newData)));
            }
        });
    }

    private void fetchFromNetwork(final LiveData<ResultType> dbSource) {
        final LiveData<ApiResponse<RequestType>> apiResponse = createCall();
        result.addSource(dbSource,
                newData -> result.setValue(Resource.loading(newData)));

        result.addSource(apiResponse, response -> {
            result.removeSource(apiResponse);
            result.removeSource(dbSource);

            if (response.isSuccessful()) {
                saveResultAndReInit(response);
            } else {
                onFetchFailed();
                result.addSource(dbSource,
                        newData -> result.setValue(Resource.error(response.errorMessage, newData)));
            }
        });
    }

    @MainThread
    private void saveResultAndReInit(ApiResponse<RequestType> response) {
        Executors.newSingleThreadExecutor().execute(() -> {
            saveCallResult(processResponse(response));
            mainThread().execute(() -> result.addSource(loadFromDb(),
                    newData -> result.setValue(Resource.success(newData))));
        });
    }

    protected void onFetchFailed() {
    }

    public LiveData<Resource<ResultType>> asLiveData() {
        return result;
    }

    @WorkerThread
    protected RequestType processResponse(ApiResponse<RequestType> response) {
        return response.body;
    }

    @WorkerThread
    protected abstract void saveCallResult(RequestType item);

    @MainThread
    protected abstract boolean shouldFetch(ResultType data);

    @MainThread
    protected abstract LiveData<ResultType> loadFromDb();

    @MainThread
    protected abstract LiveData<ApiResponse<RequestType>> createCall();

    protected Executor mainThread() {
        return new MainThreadExecutor();
    }

    private static class MainThreadExecutor implements Executor {
        private final Handler mainThreadHandler = new Handler(Looper.getMainLooper());

        @Override
        public void execute(Runnable command) {
            mainThreadHandler.post(command);
        }
    }
}

在这个示例中，我们使用了MediatorLiveData和LiveData来观察网络请求和本地数据库的变化，这样就可以在处理UI时更加简单、高效和可靠。同时，我们也可以方便地处理错误和重试逻辑，保证我们的应用程序更加健壮和可靠。