android - 等待 onConnected 调用，获取位置

Question

因此，我有自定义位置服务类，我想从中获取最后已知的位置。我有可能在连接 GoogleApiClient 之前调用 getLastKnownLocation()，所以我必须等待它然后调用 getLastKnownLocation()，但我不知道如何管理那个。我认为 RxJava 2 可以帮助我解决这个问题，但我还不熟悉该框架。这是我现在的类(class):

import android.Manifest;
import android.app.Activity;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.ActivityCompat;
import android.util.Log;

import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.location.LocationListener;
import com.google.android.gms.location.LocationRequest;
import com.google.android.gms.location.LocationServices;
import com.google.android.gms.maps.model.LatLng;

import javax.inject.Inject;

import pl.pancor.android.air.base.FragmentScope;

@FragmentScope
public class LocationService implements Location.Service,
        GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener,
        ActivityCompat.OnRequestPermissionsResultCallback {

    private static final String TAG = LocationService.class.getSimpleName();
    private static final int PERMISSIONS_REQUEST = 13;

    private GoogleApiClient mGoogleApiClient;

    private Activity mActivity;

    private android.location.Location mLastLocation;

    private Location.Receiver mReceiver;

    @Inject
    LocationService(Activity activity) {

        mActivity = activity;
    }

    @Override
    public void getLastKnownLocation() {

        if (isPermissionsGranted(true))
            getLocation();

    }

    /**
     * @param request if permissions aren't granted and {@param request} is true,
     *                then request permissions
     * @return true if location permissions are granted
     */
    private boolean isPermissionsGranted(boolean request) {

        if (ActivityCompat.checkSelfPermission(mActivity,
                Manifest.permission.ACCESS_FINE_LOCATION) !=
                PackageManager.PERMISSION_GRANTED &&
                ActivityCompat.checkSelfPermission(mActivity,
                        Manifest.permission.ACCESS_COARSE_LOCATION) !=
                        PackageManager.PERMISSION_GRANTED) {

            if (request) {
                ActivityCompat.requestPermissions(mActivity,
                        new String[]{Manifest.permission.ACCESS_FINE_LOCATION,
                                Manifest.permission.ACCESS_COARSE_LOCATION},
                        PERMISSIONS_REQUEST);
            }
            return false;
        }
        return true;
    }

    private void getLocation() {

        if (mGoogleApiClient != null)

            mLastLocation = LocationServices.FusedLocationApi
                .getLastLocation(mGoogleApiClient);

        if (mLastLocation != null) {

            LatLng latLng = new LatLng(mLastLocation.getLatitude(),
                    mLastLocation.getLongitude());
            mReceiver.lastKnownLocation(latLng);
        } else {

            Log.e(TAG, "NULLLLLLLLLLLLLLLLLLLLLLL");
        }
    }

    @Override
    public void onConnected(@Nullable Bundle bundle) {

    }

    @Override
    public void onConnectionSuspended(int i) {


    }

    @Override
    public void onConnectionFailed(@NonNull ConnectionResult connectionResult) {

    }

    @Override
    public void setupReceiver(Location.Receiver receiver) {

        mReceiver = receiver;
    }

    @Override
    public void onStart() {

        if (mGoogleApiClient != null){

            mGoogleApiClient.connect();
        } else {

            mGoogleApiClient = getGoogleApiClient();
            mGoogleApiClient.connect();
        }
    }

    @Override
    public void onStop() {

        if (mGoogleApiClient != null)
            mGoogleApiClient.disconnect();
    }

    private GoogleApiClient getGoogleApiClient(){

        return new GoogleApiClient.Builder(mActivity)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .addApi(LocationServices.API)
                .build();
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions,
                                           @NonNull int[] grantResults) {

        switch (requestCode){

            case PERMISSIONS_REQUEST:

                if (grantResults.length > 0 &&
                        grantResults[0] == PackageManager.PERMISSION_GRANTED){

                    getLastKnownLocation();
                } else {

                }
        }
    }
}

我需要以某种方式检查 mGoogleApiClient 是否已连接 (mGoogleApiClient.isConnected())，如果未连接，请等待连接，然后从 FusedLocationApi 获取位置，但我不想放置方法到 onConnected()，因为它有时会在我不想返回位置时返回位置。

Answer 1

在你在评论区解释之后，我会做这样的事情:

1. 在 Receiver/Fragment 类中，当 onConnected 适合调用 mReceiver.lastKnownLocation(latLng)< 时，我会在 LocationService 类中放置一些将变量“updateUI”设置为 true 的逻辑方法。默认值为 false，如果在接收器准备好之前调用 onConnected，方法 mReceiver.lastKnownLocation(latLng)不会被调用。

2. 另一种方法是在您的 SharedPreferences 中(或至少在 onPause 方法中)始终存储最后已知的位置。然后，您始终可以在第一次需要位置时使用它，并等待稍后更精确的位置，但这种方法在开始时不会那么精确。