第一次调用时,FusedLocationApi方法getLastLocation()始终为null

时间:2017-02-17 16:53:30

标签: java android location android-gps

在我的应用中查找有关获取当前设备位置的问题的一些帮助。下面是我正在使用的GPSLocationListener类。

import android.Manifest;
import android.app.Activity;
import android.content.pm.PackageManager;
import android.location.Location;
import android.os.Build;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
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;



/**
 * This class takes care of capturing the location of the device.
 */
public class GPSLocationListener implements GoogleApiClient.ConnectionCallbacks,
        GoogleApiClient.OnConnectionFailedListener, LocationListener,
        ActivityCompat.OnRequestPermissionsResultCallback {


    protected static final String TAG = "location-updates-sample";

    public static final int LOCATION_RESQUEST = 1;
    /**
     * The desired interval for location updates. Inexact. Updates may be more or less frequent.
     */
    public static final long UPDATE_INTERVAL_IN_MILLISECONDS = 10000;

    /**
     * The fastest rate for active location updates. Exact. Updates will never be more frequent
     * than this value.
     */
    public static final long FASTEST_UPDATE_INTERVAL_IN_MILLISECONDS =
            UPDATE_INTERVAL_IN_MILLISECONDS / 2;

    /**
     * Provides the entry point to Google Play services.
     */
    protected GoogleApiClient mGoogleApiClient;

    /**
     * Stores parameters for requests to the FusedLocationProviderApi.
     */
    protected LocationRequest mLocationRequest;

    /**
     * Represents a geographical location.
     */
    protected Location mCurrentLocation;

    private Activity mActivity;

    public double lat;
    public double lon;

    public GPSLocationListener(Activity activity) {
        this.mActivity = activity;
        // Kick off the process of building a GoogleApiClient and requesting the LocationServices API.
        buildGoogleApiClient();
    }

    /**
     * Builds a GoogleApiClient. Uses the {@code #addApi} method to request the
     * LocationServices API.
     */
    protected synchronized void buildGoogleApiClient() {
        Log.i(TAG, "Building GoogleApiClient");
        mGoogleApiClient = new GoogleApiClient.Builder(mActivity)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .addApi(LocationServices.API)
                .build();
        createLocationRequest();
    }

    /**
     * Sets up the location request. Android has two location request settings:
     * {@code ACCESS_COARSE_LOCATION} and {@code ACCESS_FINE_LOCATION}. These settings control
     * the accuracy of the current location. This sample uses ACCESS_FINE_LOCATION, as defined in
     * the AndroidManifest.xml.
     * <p/>
     * When the ACCESS_FINE_LOCATION setting is specified, combined with a fast update
     * interval (5 seconds), the Fused Navigation Provider API returns location updates that are
     * accurate to within a few feet.
     * <p/>
     * These settings are appropriate for mapping applications that show real-time location
     * updates.
     */
    protected void createLocationRequest() {
        mLocationRequest = new LocationRequest();

        // Sets the desired interval for active location updates. This interval is
        // inexact. You may not receive updates at all if no location sources are available, or
        // you may receive them slower than requested. You may also receive updates faster than
        // requested if other applications are requesting location at a faster interval.
        mLocationRequest.setInterval(UPDATE_INTERVAL_IN_MILLISECONDS);

        // Sets the fastest rate for active location updates. This interval is exact, and your
        // application will never receive updates faster than this value.
        mLocationRequest.setFastestInterval(FASTEST_UPDATE_INTERVAL_IN_MILLISECONDS);

        mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
    }

    /**
     * Requests location updates from the FusedLocationApi.
     */
    public void startLocationUpdates(){
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            if (ContextCompat.checkSelfPermission(this.mActivity, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this.mActivity, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this.mActivity, Manifest.permission.INTERNET) != PackageManager.PERMISSION_GRANTED) {
                //return;
            }else {
                try {
                    ActivityCompat.requestPermissions(this.mActivity, new String[]{Manifest.permission.ACCESS_FINE_LOCATION,
                                    Manifest.permission.ACCESS_COARSE_LOCATION, Manifest.permission.INTERNET},
                            LOCATION_RESQUEST);
                }catch (Exception e){
                    e.printStackTrace();
                }
            }
            // If the initial location was never previously requested, we use
            // FusedLocationApi.getLastLocation() to get it. If it was previously requested, we store
            // its value in the Bundle and check for it in onCreate().
            LocationServices.FusedLocationApi.requestLocationUpdates(
                    mGoogleApiClient, mLocationRequest, this);
        }
    }

    /**
     * Removes location updates from the FusedLocationApi.
     */
    protected void stopLocationUpdates() {
        // It is a good practice to remove location requests when the activity is in a paused or
        // stopped state. Doing so helps battery performance and is especially
        // recommended in applications that request frequent location updates.

        // The final argument to {@code requestLocationUpdates()} is a LocationListener
        // (http://developer.android.com/reference/com/google/android/gms/location/LocationListener.html).
        LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, this);
    }

    public void onStart() {
        mGoogleApiClient.connect();
        //createLocationRequest();
        // Within {@code onPause()}, we pause location updates, but leave the
        // connection to GoogleApiClient intact.  Here, we resume receiving
        // location updates if the user has requested them.

    }

    public void onStop() {
        // Stop location updates to save battery, but don't disconnect the GoogleApiClient object.
        if (mGoogleApiClient.isConnected()) {
            stopLocationUpdates();
            mGoogleApiClient.disconnect();
        }

    }

    /**
     * Runs when a GoogleApiClient object successfully connects.
     */
    @Override
    public void onConnected(Bundle connectionHint) {
        Log.i(TAG, "Connected to GoogleApiClient");
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            if (ContextCompat.checkSelfPermission(this.mActivity, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this.mActivity, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this.mActivity, Manifest.permission.INTERNET) != PackageManager.PERMISSION_GRANTED) {
                Log.i(TAG, "onConnected: Just empty if statement");
            }else {
                try {
                    ActivityCompat.requestPermissions(this.mActivity, new String[]{Manifest.permission.ACCESS_FINE_LOCATION,
                                    Manifest.permission.ACCESS_COARSE_LOCATION, Manifest.permission.INTERNET},
                            LOCATION_RESQUEST);
                }catch (Exception e){
                    e.printStackTrace();
                }
            }
            mCurrentLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
            if (mCurrentLocation == null) {
                mCurrentLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
                Log.i(TAG, "onConnected  " + String.valueOf(mCurrentLocation));
            }
        }
    }

    /**
     * Callback that fires when the location changes.
     */
    @Override
    public void onLocationChanged(Location location) {
        mCurrentLocation = location;
        Log.i(TAG, "onLocationChanged: " + String.valueOf(mCurrentLocation.getLatitude()));
        Log.i(TAG, "onLocationChanged: " + String.valueOf(mCurrentLocation.getLongitude()));
    }

    @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
    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());
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            mActivity.onRequestPermissionsResult(requestCode, permissions, grantResults);
        }
        switch (requestCode){
            case LOCATION_RESQUEST:
                if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED){
                    startLocationUpdates(); // Calling this here is the only place that does not make the app crash
                    getCurrentLocation();
                }else {
                    Log.i(TAG, "onRequestPermissionsResult: Need Permissions");
                    return;
                }
                break;
            default:
                break;
        }
        return;
    }

    public void getCurrentLocation(){
        if (mCurrentLocation != null){
            lat = mCurrentLocation.getLatitude();
            lon = mCurrentLocation.getLongitude();
            Log.i(TAG, "getCurrentLocation(): " + String.valueOf(mCurrentLocation.getLatitude()));
            Log.i(TAG, "getCurrentLocation(): " + String.valueOf(mCurrentLocation.getLongitude()));
        }
    }

    public GoogleApiClient getGoogleApiClient(){
        return mGoogleApiClient;
    }

}

在设置中已启用GPS的实际设备上尝试此操作,我得到一些奇怪的行为。如果我没有,请调用startLocationUpdates()方法或我在onRequestPermissionsResult()方法中调用它,应用程序启动正常,当我授予设备位置权限时,mCurrentLocation对象为空,但不会崩溃。我停止应用程序然后再次启动,mCurrentLocation具有我在logcat中可以看到的纬度和经度坐标,这是我首先想要的,但它们只保留任何值,在第二个之后发射。现在,如果我卸载应用程序并尝试在任何地方调用startLocationUpdates()方法,应用程序会在启动时崩溃并显示错误:

Client must have ACCESS_FINE_LOCATION permission to request PRIORITY_HIGH_ACCURACY locations.

但我正在检查onConnected()方法以及startLocationUpdates()方法中的权限,虽然我不认为这是正确的,但这是我可以获得Android Studio的唯一方法不强调

LocationServices.FusedLocationApi.requestLocationUpdates(
                    mGoogleApiClient, mLocationRequest, this); 
带有权限警告的

红色语句。

以下是Activity,我尝试使用mapItBtnRespond()方法更新位置信息。

package com.example.bigdaddy.as_built_weldmapper;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.Toast;

import com.example.bigdaddy.as_built_weldmapper.utilities.BendHelper;
import com.example.bigdaddy.as_built_weldmapper.utilities.GPSLocationListener;

public class SagActivity extends AppCompatActivity implements AdapterView.OnItemSelectedListener,
        MajorButtonFragment.OnFragmentInteractionListener, Communicator{

    /* Using this to insert into the Bend Direction field. */
    public static String SAG_DIRECTION = "SAG";

    /* This spinner holds the bend types */
    Spinner mSagBendTypesSpinner;

    /* Using this string to collect what was selected for the spinner type */
    private String mBendTypeSpinnerVal;

    /* All the EditText for the Activity */
    private EditText mSagGpsShotEt;
    private EditText mSagExistingGpsEt;
    private EditText mSagCoverEt;
    private EditText mSagDegreeEt;
    private EditText mSagDistanceFromEt;
    private EditText mSagNotesEt;
    private EditText mSagOccupyIdEt;
    private EditText mSagStationNumEt;

    private GPSLocationListener mGPSLocationListener;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_sag);

        mGPSLocationListener = new GPSLocationListener(SagActivity.this);

        /* checking if the MajorButtonFragment is null */
        if (findViewById(R.id.majorButtonFragment) != null) {
            if (savedInstanceState != null) {
                return;
            }
        }

        /* Referencing the spinner and setting the itemsSelectedListener */
        mSagBendTypesSpinner = (Spinner) findViewById(R.id.bend_types_spinner);
        mSagBendTypesSpinner.setOnItemSelectedListener((AdapterView.OnItemSelectedListener) this);
        /* Create an ArrayAdapter using the string array and a default spinner layout */
        ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this,
                R.array.bend_types_array, android.R.layout.simple_spinner_item);
        /* Specify the layout to use when the list of choices appears */
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        /* Apply the adapter to the spinner */
        mSagBendTypesSpinner.setAdapter(adapter);

        /* Referencing and calling all the EditText for the Activity */
        mSagGpsShotEt = (EditText) findViewById(R.id.eTextGpsShotForSag);
        mSagExistingGpsEt = (EditText) findViewById(R.id.eTextExistGradeForSag);
        mSagCoverEt = (EditText) findViewById(R.id.eTextCoverForSag);
        mSagDegreeEt = (EditText) findViewById(R.id.eTextDegreeForSag);
        mSagDistanceFromEt = (EditText) findViewById(R.id.eTextDistanceFromForSag);
        mSagNotesEt = (EditText) findViewById(R.id.eTextNotesForSagActivity);
        mSagOccupyIdEt = (EditText) findViewById(R.id.eTextJointIdSagActivity);
        mSagStationNumEt = (EditText) findViewById(R.id.eTextStationNumSagActivity);
    } /*onCreate() ends here.*/

    @Override
    protected void onStart() {
        super.onStart();
        Log.i("SagActivity", "onStart: ");
        /* Starting the location listener here (GoogleApiClient) */
        if (mGPSLocationListener != null){
            mGPSLocationListener.onStart();
        }
    }

    @Override
    protected void onStop() {
        super.onStop();
        Log.i("SagActivity", "onStop: ");
        /* Stopping the location listener here (GoogleApiClient) */
        if (mGPSLocationListener != null){
            mGPSLocationListener.onStop();
        }
    }

    @Override
    public void onLocalVoiceInteractionStopped() {
        super.onLocalVoiceInteractionStopped();
    }

    @Override
    public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
        mBendTypeSpinnerVal = mSagBendTypesSpinner.getSelectedItem().toString();
    }

    @Override
    public void onNothingSelected(AdapterView<?> adapterView) {

    }

    @Override
    public void exitBtnRespond() {

    }

    /**
     * This overridden method comes from the Communicator Interface and is used globally in all
     * Activities that implement it to Store (write) a transaction to the database.
     * The utility class saveAndInsertBend() method is invoked here.
     */
    @Override
    public void storeBtnRespond() {
        BendHelper.saveAndInsertBend(SagActivity.this, SAG_DIRECTION, mBendTypeSpinnerVal, mSagStationNumEt,
                mSagOccupyIdEt, mSagDegreeEt, mSagDistanceFromEt, mSagGpsShotEt, mSagExistingGpsEt,
                mSagCoverEt, mSagNotesEt);
    }

    @Override
    public void mapItBtnRespond() {
        Toast.makeText(this, "MapItBtn clicked in SagActivity",Toast.LENGTH_LONG).show();
        mGPSLocationListener.getCurrentLocation();
        Log.i("SagActivity", "mapItBtnRespond: " + String.valueOf(mGPSLocationListener.lat));
        Log.i("SagActivity", "mapItBtnRespond: " + String.valueOf(mGPSLocationListener.lon));
    }

    @Override
    public void onFragmentInteraction() {

    }

}

我在这里做错了什么?任何帮助都会非常感激,因为我显然与Permissions混淆了。非常感谢任何指导。

1 个答案:

答案 0 :(得分:1)

您在onConnected()中要求FINE_LOCATION权限,但在连接GPS时会调用onConnected。这就是你获得权限错误的原因。

你应该删除它:

mCurrentLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);

来自onConnected()。将此添加到带有权限请求的getCurrentLocation():

public void getCurrentLocation(){
        //Request permission here
        mCurrentLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
        if (mCurrentLocation != null){
            lat = mCurrentLocation.getLatitude();
            lon = mCurrentLocation.getLongitude();
            Log.i(TAG, "getCurrentLocation(): " + String.valueOf(mCurrentLocation.getLatitude()));
            Log.i(TAG, "getCurrentLocation(): " + String.valueOf(mCurrentLocation.getLongitude()));
        }
    }

然后在onConnected()中调用此方法:

 @Override
    public void onConnected(Bundle connectionHint) {
        Log.i(TAG, "Connected to GoogleApiClient");
            getCurrentLocation();
    }