我已遵循本指南https://developer.android.com/training/location/retrieve-current.html#permissions，但我无法收到最后一个位置。
我只需要一次这个位置。
这是我的代码：
public class MainActivity extends ActionBarActivity implements GoogleApiClient.ConnectionCallbacks,
GoogleApiClient.OnConnectionFailedListener {
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 GoogleApiClient mGoogleApiClient;
private Location mLastLocation;
private double mLatitude;
private double mLongitude;
@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;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ButterKnife.bind(this);
mProgressBar.setVisibility(View.INVISIBLE);
buildGoogleApiClient();
//mLatitude = 37.8267;
//mLongitude = -122.423;
mRefreshImageView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
getForecast(mLatitude, mLongitude);
}
});
getForecast(mLatitude, mLongitude);
}
private void getForecast(double latitude, double longitude) {
String apiKey = "48fb6c0ca3567d0b17bf99b400ef5606";
String forecastUrl = "https://api.forecast.io/forecast/" + apiKey +
"/" + latitude + "," + longitude;
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) {
Log.e(TAG, "Exception caught: ", e);
}
}
});
}
else {
Toast.makeText(this, getString(R.string.network_unavailable_message),
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() {
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 = getResources().getDrawable(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.setTime(jsonDay.getLong("time"));
day.setTemperatureMax(jsonDay.getDouble("temperatureMax"));
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.getInt("time"));
current.setSummary(currently.getString("summary"));
current.setTemperature(currently.getInt("temperature"));
current.setIcon(currently.getString("icon"));
current.setPrecipChance(currently.getDouble("precipProbability"));
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);
}
protected synchronized void buildGoogleApiClient() {
mGoogleApiClient = new GoogleApiClient.Builder(this)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API)
.build();
}
@Override
public void onConnected(Bundle bundle) {
mLastLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
if (mLastLocation != null) {
mLatitude = mLastLocation.getLatitude();
mLongitude = mLastLocation.getLongitude();
}
}
@Override
public void onConnectionSuspended(int i) {
}
@Override
public void onConnectionFailed(ConnectionResult connectionResult) {
}
}
`
答案 0 :(得分：0)
getLastLocation()很有可能返回null。它也不会请求新位置，因此即使您获得了位置，它也可能非常陈旧，并且不会反映当前位置。最好注册一个监听器，即使你在第一次onLocationChanged（）回调后取消注册也是如此。
这个问题被问了很多，通常被标记为questions like this one
的副本但是，在您的情况下，您似乎忘记致电connect()：
buildGoogleApiClient();
mGoogleApiClient.connect(); //added
您可以使用this answer中的代码作为注册位置回调的参考，如果您想获得准确的当前位置，建议使用此代码。
编辑：由于您只需要一个位置，以下是该代码的略微修改版本，该版本请求位置更新，然后在第一个位置进入后取消注册位置更新。
public class MainActivity extends Activity implements
GoogleApiClient.ConnectionCallbacks,
GoogleApiClient.OnConnectionFailedListener, LocationListener {
LocationRequest mLocationRequest;
GoogleApiClient mGoogleApiClient;
private Location mLastLocation;
private double mLatitude;
private double mLongitude;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
buildGoogleApiClient();
mGoogleApiClient.connect();
}
@Override
protected void onPause(){
super.onPause();
if (mGoogleApiClient != null) {
LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, this);
}
}
protected synchronized void buildGoogleApiClient() {
mGoogleApiClient = new GoogleApiClient.Builder(this)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API)
.build();
}
@Override
public void onConnected(Bundle bundle) {
mLocationRequest = new LocationRequest();
mLocationRequest.setInterval(1000);
mLocationRequest.setFastestInterval(1000);
mLocationRequest.setPriority(LocationRequest.PRIORITY_BALANCED_POWER_ACCURACY);
//mLocationRequest.setSmallestDisplacement(0.1F);
LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, this);
}
@Override
public void onConnectionSuspended(int i) {
Toast.makeText(this,"onConnectionSuspended",Toast.LENGTH_SHORT).show();
}
@Override
public void onConnectionFailed(ConnectionResult connectionResult) {
Toast.makeText(this,"onConnectionFailed",Toast.LENGTH_SHORT).show();
}
@Override
public void onLocationChanged(Location location) {
mLastLocation = location;
//no need to do a null check here:
mLatitude = location.getLatitude();
mLongitude = location.getLongitude();
//remove location updates if you just need one location:
if (mGoogleApiClient != null) {
LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, this);
}
}
}