三星 Note 2 无法访问 onLocationChanged()

Question

它适用于除 Galaxy Note 2 之外的大多数设备。它连接到 Google 客户端，但无法访问实现 LocationListener 的 onLocationChanged()。任何人都知道它是什么原因造成的，为什么只在这个设备上？

@Override
public void onLocationChanged(Location location) {

    mLastLocation = location;

    if (mLastLocation != null) {
        lat = mLastLocation.getLatitude();
        lng = mLastLocation.getLongitude();

        Toast.makeText(getApplicationContext(), String.valueOf(lat) + "/" + String.valueOf(lng), Toast.LENGTH_LONG).show();

        serverUrl = "http://(my server)/offers?lat=" + String.valueOf(mLastLocation.getLatitude())
                            + "&lng=" + String.valueOf(mLastLocation.getLongitude()) + "&distance=1";
        // save
        makeTag(serverUrl);

        // after getting location data - unregister listener
                    LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, mFusedLocationCallback);
        new GetBackgroundUpdate().execute();
    } else {
        // get data from server and update GridView
        new GetBackgroundUpdate().execute();
        Toast.makeText(getApplicationContext(), R.string.no_location_detected, Toast.LENGTH_LONG).show();

     }
/**
Location methods
*/
protected synchronized void buildGoogleApiClient() {
    mGoogleApiClient = new GoogleApiClient.Builder(this)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .addApi(LocationServices.API)
                .build();
}

/**
* Runs when a GoogleApiClient object successfully connects.
*/
@Override
public void onConnected(Bundle connectionHint) {
    // Provides a simple way of getting a device's location and is well suited for
    // applications that do not require a fine-grained location and that do not need location
    // updates. Gets the best and most recent location currently available, which may be null
    // in rare cases when a location is not available.
    mLastLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
    mLocationRequest = new LocationRequest();
    mLocationRequest.setInterval(1000);
    mLocationRequest.setFastestInterval(500);
    mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);

    LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, mFusedLocationCallback);

}

@Override
public void onConnectionFailed(ConnectionResult result) {
    // Refer to the javadoc for ConnectionResult to see what error codes might be returned in
    // onConnectionFailed.
    Log.i(TAG, "Connection failed: ConnectionResult.getErrorCode() = " + result.getErrorCode());

    if (mResolvingError) {
        // Already attempting to resolve an error.
        return;
    } else if (result.hasResolution()) {
        try {
            mResolvingError = true;
            result.startResolutionForResult(this, REQUEST_RESOLVE_ERROR);
        } catch (IntentSender.SendIntentException e) {
            // There was an error with the resolution intent. Try again.
            mGoogleApiClient.connect();
        }
    } else {
        // Show dialog using GooglePlayServicesUtil.getErrorDialog()
        final AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setMessage(String.valueOf(result.getErrorCode()))
                    .setCancelable(false)
                    .setNegativeButton("Ok", new DialogInterface.OnClickListener() {
                        public void onClick(final DialogInterface dialog, final int id) {
                            dialog.cancel();
                        }
                    });
        final AlertDialog alert = builder.create();
        alert.show();
        mResolvingError = true;
    }

    //new GetBackgroundUpdate().execute();
}

@Override
public void onConnectionSuspended(int cause) {
    // The connection to Google Play services was lost for some reason. We call connect() to
    // attempt to re-establish the connection.
    Log.i(TAG, "Connection suspended");
    mGoogleApiClient.connect();
}

@Override
protected void onStart() {
    super.onStart();
    mGoogleApiClient.connect();
}

@Override
protected void onStop() {
    super.onStop();
    if (mGoogleApiClient.isConnected()) {
        mGoogleApiClient.disconnect();
    }
}

Answer 1

编辑：从您的评论中NullPointerException 发生的行中，确保mLastLocation 不为空。

if (mLastLocation != null){
    address = server + String.valueOf(mLastLocation.getLatitude()) + "&lng=" + String.valueOf(mLastLocation.getLongitude()) + "&distance=" + distance;
} 

另外需要注意的是，在使用之前，您应该始终确保mGoogleApiClient 不为空且已连接。

if (mGoogleApiClient != null && mGoogleApiClient.isConnected()){
  //..... use mGoogleApiClient.....
}

See documentation here

您还应该添加一项检查以查看 Google Play 服务是否可用，因为有时设备上可用的版本低于您编译应用时使用的版本。如果是这种情况，您可以显示一个对话框。

以下是如何检查 Google Play 服务是否可用。

private boolean isGooglePlayServicesAvailable() {
        int status = GooglePlayServicesUtil.isGooglePlayServicesAvailable(this);
        if (ConnectionResult.SUCCESS == status) {
            return true;
        } else {
            GooglePlayServicesUtil.getErrorDialog(status, this, 0).show();
            return false;
        }
    }

请注意，getLastLocation() 很容易返回 null，因此如果您从第一次调用 getLastLocation() 中获得 null 值，那么一个好的方法是注册一个位置侦听器。
看到这个帖子：LocationClient getLastLocation() return null

这里是如何注册LocationListener的指南：

创建监听器：

LocationCallback mFusedLocationCallback = new LocationCallback();

类定义：

private class LocationCallback implements LocationListener {

        public LocationCallback() {

        }

        @Override
        public void onLocationChanged(Location location) {

                 mLastLocation = location;
                 lat = String.valueOf(mLastLocation.getLatitude());
                 lng = String.valueOf(mLastLocation.getLongitude());


             }
    };

然后只需注册LocationListener：

  mLocationRequest = new LocationRequest();
  mLocationRequest.setInterval(minTime);
  mLocationRequest.setFastestInterval(fastestTime);
  mLocationRequest.setPriority(LocationRequest.PRIORITY_BALANCED_POWER_ACCURACY);
  mLocationRequest.setSmallestDisplacement(distanceThreshold);

 LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, mFusedLocationCallback);

编辑：在注册位置回调之前，您应该等待 API 连接，它应该是这样的：

/**
 * Runs when a GoogleApiClient object successfully connects.
 */
@Override
public void onConnected(Bundle connectionHint) {
    // Provides a simple way of getting a device's location and is well suited for
    // applications that do not require a fine-grained location and that do not need location
    // updates. Gets the best and most recent location currently available, which may be null
    // in rare cases when a location is not available.
    mLastLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
    if (mLastLocation != null) {
        lat = String.valueOf(mLastLocation.getLatitude());
        lng = String.valueOf(mLastLocation.getLongitude());
    } else {
        Toast.makeText(this, R.string.no_location_detected, Toast.LENGTH_LONG).show();
    }


     mLocationRequest = new LocationRequest();
     mLocationRequest.setInterval(1000);
     mLocationRequest.setFastestInterval(500);
     mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);

     LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, mFusedLocationCallback);
}

文档： for requestLocationUpdates.... 和 LocationRequest。

最后一件事，请确保您的 AndroidManifest.xml 中的 application 标记内包含此内容：

  <meta-data
    android:name="com.google.android.gms.version"
    android:value="@integer/google_play_services_version" />