我正在尝试将GPS功能添加到我的android应用中，gps坐标每次显示为0.0、0.0

Question

I'd like to check GPS both when the app is started and when the refresh button is hit, and use those data points, in the form of mLatitude and mLongitude to call the weather api. Eventually I'm going to geocode the city but right now for debugging purposes I'm outputting the GPS coordinates to the locationLabel textview.

my MainActivity.java:

package com.example.paxie.stormy.ui;

import android.Manifest;
import android.annotation.TargetApi;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.pm.PackageManager;
import android.graphics.drawable.Drawable;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.Build;
import android.os.Bundle;
import android.provider.Settings;
import android.support.annotation.NonNull;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.ImageView;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;

import com.example.paxie.stormy.GPS_Service;
import com.example.paxie.stormy.R;
import com.example.paxie.stormy.weather.Current;
import com.example.paxie.stormy.weather.Day;
import com.example.paxie.stormy.weather.Forecast;
import com.example.paxie.stormy.weather.Hour;
import com.squareup.okhttp.Call;
import com.squareup.okhttp.Callback;
import com.squareup.okhttp.OkHttpClient;
import com.squareup.okhttp.Request;
import com.squareup.okhttp.Response;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.IOException;

import butterknife.Bind;
import butterknife.ButterKnife;
import butterknife.OnClick;


public class MainActivity extends AppCompatActivity {

    public static final String TAG = MainActivity.class.getSimpleName();
    public static final String DAILY_FORECAST = "DAILY_FORECAST";
    public static final String HOURLY_FORECAST = "HOURLY_FORECAST";
    private Forecast mForecast;
    private double mLatitude;
    private double mLongitude;
    private BroadcastReceiver broadcastReceiver;

    @Bind(R.id.timeLabel)
    TextView mTimeLabel;
    @Bind(R.id.temperatureLabel)
    TextView mTemperatureLabel;
    @Bind(R.id.humidityValue)
    TextView mHumidityValue;
    @Bind(R.id.precipValue)
    TextView mPrecipValue;
    @Bind(R.id.summaryLabel)
    TextView mSummaryLabel;
    @Bind(R.id.iconImageView)
    ImageView mIconImageView;
    @Bind(R.id.refreshImageView)
    ImageView mRefreshImageView;
    @Bind(R.id.progressBar)
    ProgressBar mProgressBar;
    @Bind(R.id.locationLabel)
    TextView mLocationlabel;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ButterKnife.bind(this);

        mProgressBar.setVisibility(View.INVISIBLE);

        mRefreshImageView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                getForecast();
            }
        });


        getForecast();
        Log.d(TAG, "Main UI code is running!");
    }

    private void getForecast() {
        if(!runtime_permissions())
        checkGPS();
        String apiKey = "1621390f8c36997cb1904914b726df52";
        String forecastUrl = "https://api.forecast.io/forecast/" + apiKey +
                "/" + mLatitude + "," + mLongitude;

        if (isNetworkAvailable()) {
            toggleRefresh();

            OkHttpClient client = new OkHttpClient();
            Request request = new Request.Builder()
                    .url(forecastUrl)
                    .build();

            Call call = client.newCall(request);
            call.enqueue(new Callback() {
                @Override
                public void onFailure(Request request, IOException e) {
                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            toggleRefresh();
                        }
                    });
                    alertUserAboutError();
                }

                @Override
                public void onResponse(Response response) throws IOException {
                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            toggleRefresh();
                        }
                    });
                    try {
                        String jsonData = response.body().string();
                        Log.v(TAG, jsonData);
                        if (response.isSuccessful()) {
                            mForecast = parseForecastDetails(jsonData);
                            runOnUiThread(new Runnable() {
                                @Override
                                public void run() {
                                    updateDisplay();
                                }
                            });

                        } else {
                            alertUserAboutError();

                        }
                    } catch (IOException e)

                    {
                        Log.e(TAG, "Exception caught: ", e);
                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
            });
        } else {
            Toast.makeText(this, "Network is currently unavailable!", Toast.LENGTH_LONG).show();
        }
    }


    private void toggleRefresh() {
        if (mProgressBar.getVisibility() == View.INVISIBLE) {
            mProgressBar.setVisibility(View.VISIBLE);
            mRefreshImageView.setVisibility(View.INVISIBLE);
        } else {
            mProgressBar.setVisibility(View.INVISIBLE);
            mRefreshImageView.setVisibility(View.VISIBLE);
        }
    }

    private void updateDisplay() {
        mLocationlabel.setText(mLatitude + " " + mLongitude);
        Current current = mForecast.getCurrent();
        mTemperatureLabel.setText(current.getTemperature() + "");
        mTimeLabel.setText("At " + current.getFormattedTime() + " it will be:");
        mHumidityValue.setText(current.getHumidity() + "");
        mPrecipValue.setText(current.getPrecipChance() + "%");
        mSummaryLabel.setText(current.getSummary());
        Drawable drawable = ContextCompat.getDrawable(this, current.getIconId());
        mIconImageView.setImageDrawable(drawable);
    }

    private Forecast parseForecastDetails(String jsonData) throws JSONException {
        Forecast forecast = new Forecast();
        forecast.setCurrent(getCurrentDetails(jsonData));
        forecast.setHourlyForecast(getHourlyForecast(jsonData));
        forecast.setDailyForecast(getDailyForecast(jsonData));

        return forecast;

    }

    private Day[] getDailyForecast(String jsonData) throws JSONException {
        JSONObject forecast = new JSONObject(jsonData);
        String timezone = forecast.getString("timezone");
        JSONObject daily = forecast.getJSONObject("daily");
        JSONArray data = daily.getJSONArray("data");

        Day[] days = new Day[data.length()];

        for (int i = 0; i < data.length(); i++) {
            JSONObject jsonDay = data.getJSONObject(i);
            Day day = new Day();

            day.setSummary(jsonDay.getString("summary"));
            day.setIcon(jsonDay.getString("icon"));
            day.setTemperatureMax(jsonDay.getDouble("temperatureMax"));
            day.setTime(jsonDay.getLong("time"));
            day.setTimeZone(timezone);

            days[i] = day;

        }
        return days;
    }

    private Hour[] getHourlyForecast(String jsonData) throws JSONException {
        JSONObject forecast = new JSONObject(jsonData);
        String timezone = forecast.getString("timezone");
        JSONObject hourly = forecast.getJSONObject("hourly");
        JSONArray data = hourly.getJSONArray("data");

        Hour[] hours = new Hour[data.length()];

        for (int i = 0; i < data.length(); i++) {
            JSONObject jsonHour = data.getJSONObject(i);
            Hour hour = new Hour();
            hour.setSummary(jsonHour.getString("summary"));
            hour.setTemperature(jsonHour.getDouble("temperature"));
            hour.setIcon(jsonHour.getString("icon"));
            hour.setTime(jsonHour.getLong("time"));
            hour.setTimeZone(timezone);

            hours[i] = hour;

        }
        return hours;
    }

    private Current getCurrentDetails(String jsonData) throws JSONException {
        JSONObject forecast = new JSONObject(jsonData);
        String timezone = forecast.getString("timezone");
        Log.i(TAG, "From JSON:  " + timezone);

        JSONObject currently = forecast.getJSONObject("currently");
        Current current = new Current();
        current.setHumidity(currently.getDouble("humidity"));
        current.setTime(currently.getLong("time"));
        current.setIcon(currently.getString("icon"));
        current.setPrecipChance(currently.getDouble("precipProbability"));
        current.setSummary(currently.getString("summary"));
        current.setTemperature(currently.getDouble("temperature"));
        current.setTimeZone(timezone);

        Log.d(TAG, current.getFormattedTime());

        return current;
    }

    private boolean isNetworkAvailable() {
        ConnectivityManager manager = (ConnectivityManager)
                getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo networkInfo = manager.getActiveNetworkInfo();
        boolean isAvailable = false;
        if (networkInfo != null && networkInfo.isConnected()) {
            isAvailable = true;
        }
        return isAvailable;
    }


    private void alertUserAboutError() {
        AlertDialogFragment dialog = new AlertDialogFragment();
        dialog.show(getFragmentManager(), "error_dialog");
    }


    @OnClick(R.id.dailyButton)
    public void startDailyActivity(View view) {
        Intent intent = new Intent(this, DailyForecastActivity.class);
        intent.putExtra(DAILY_FORECAST, mForecast.getDailyForecast());
        startActivity(intent);

    }

    @OnClick(R.id.hourlyButton)
    public void startHourlyActivity(View view) {
        Intent intent = new Intent(this, HourlyForecastActivity.class);
        intent.putExtra(HOURLY_FORECAST, mForecast.getHourlyForecast());
        startActivity(intent);
    }

    private void checkGPS() {
        if (broadcastReceiver == null) {
            broadcastReceiver = new BroadcastReceiver() {
                @Override
                public void onReceive(Context context, Intent intent) {
                    mLatitude = (double) intent.getExtras().get("latitude");
                    mLongitude = (double) intent.getExtras().get("longitude");
                }
            };
        }
        registerReceiver(broadcastReceiver, new IntentFilter("location_update"));
    }

    private boolean runtime_permissions() {
        if (Build.VERSION.SDK_INT >= 23 && ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {

            requestPermissions(new String[]{Manifest.permission.ACCESS_FINE_LOCATION, Manifest.permission.ACCESS_COARSE_LOCATION}, 100);

            return true;
        }
        return false;
    }


    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if (requestCode == 100) {
            if (grantResults[0] == PackageManager.PERMISSION_GRANTED && grantResults[1] == PackageManager.PERMISSION_GRANTED) {
                getForecast();
            } else {
                runtime_permissions();
            }
        }
    }

    @Override
    protected void onResume() {
        super.onResume();
        checkGPS();
    }
}

my GPSservice.java:

package com.example.paxie.stormy;

import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.os.IBinder;
import android.provider.Settings;
import android.support.annotation.Nullable;

/**
 * Created by paxie on 10/27/16.
 */
public class GPS_Service extends Service {
    private LocationListener listener;
    private LocationManager locationManager;

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public void onCreate() {

        listener = new LocationListener() {
            @Override
            public void onLocationChanged(Location location) {
                Intent i = new Intent("location_update");
                i.putExtra("coordinates",location.getLongitude()+" "+location.getLatitude());
                i.putExtra("longitude", location.getLongitude());
                i.putExtra("latitude", location.getLatitude());
                sendBroadcast(i);
            }

            @Override
            public void onStatusChanged(String s, int i, Bundle bundle) {

            }

            @Override
            public void onProviderEnabled(String s) {

            }

            @Override
            public void onProviderDisabled(String s) {
                Intent i = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
                i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                startActivity(i);
            }
        };

        locationManager = (LocationManager) getApplicationContext().getSystemService(Context.LOCATION_SERVICE);

        //noinspection MissingPermission
        locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER,3000,0,listener);

    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        if(locationManager != null){
            //noinspection MissingPermission
            locationManager.removeUpdates(listener);
        }
    }
}

Answer 1

Here are two things you can try:

1. Please ensure you have included the ACCESS_FINE_LOCATION and ACCESS_COARSE_LOCATION permissions in your manifest. If your app targets Android API 23 and above, you will need to include runtime permission handling.

2. Instead of having a LocationListener object as a class member, you should have your Service implement it as an interface and implement its onLocationChanged() method.

Apart from this, you really should consider using the location APIs' in Google Play Services, rather than those in AOSP (ie android.location ).

See Making Your App Location-Aware