如何从 Android 中的 Worker 类访问我的 Rooms 数据库的存储库？

Question

我在我的应用程序中有一个Worker类，我想从我的Rooms数据库中获取数据。由于我使用MVVM架构，我如何在我的Worker类中使用存储库从数据库中获取数据?

——代码

工人阶级

public class SendNotification extends Worker {

public SendNotification(@NonNull Context context, @NonNull WorkerParameters workerParams) {
super(context, workerParams);
}
@RequiresApi(api = Build.VERSION_CODES.M)
@NonNull
@Override
public Result doWork() {
String flightnumber = getInputData().getString("flight");
String date = getInputData().getString("date");

sendNotification(flightnumber,date);
return Result.success();
}}

库

public class FlightRepository {
private FlightDao flightDao;
private LiveData<List<Flight>> allFlights;
public FlightRepository(Application application) {
FlightDatabase database = FlightDatabase.getInstance(application);
flightDao = database.flightDao();
allFlights = flightDao.getAllFlights();
}
public void insert(Flight flight) {
new InsertFlightAsyncTask(flightDao).execute(flight);
}
public void update(Flight flight) {
new UpdateFlightAsyncTask(flightDao).execute(flight);
}
public void delete(Flight flight) {
new DeleteFlightAsyncTask(flightDao).execute(flight);
}
public void deleteAllFlights() {
new DeleteAllFlightsAsyncTask(flightDao).execute();
}
public LiveData<List<Flight>> getAllFlights() {
return allFlights;
}
public Flight getFlight(String flightNumber, String date){
return flightDao.getFlight(flightNumber,date);
}
public boolean existsFlight(String flightNumber, String date){
return flightDao.existsFlight(flightNumber, date);
}

Answer 1

您应该能够在Worker中创建FlightRepository的实例:

public class SendNotification extends Worker {
private FlightRepository flightRepo;

public SendNotification(@NonNull Context context, @NonNull WorkerParameters workerParams) {
super(context, workerParams);
this.flightRepo = new FlightRepository(context)
}
@RequiresApi(api = Build.VERSION_CODES.M)
@NonNull
@Override
public Result doWork() {
String flightnumber = getInputData().getString("flight");
String date = getInputData().getString("date");

// Do what is needed with flightRepo
sendNotification(flightnumber,date);
return Result.success();
}}

在这里做一些假设。我会重构FlightDatabase以接受Context，而不是Application。我不确定为什么数据库需要访问Application