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尋找一些關於獲取當前設備位置的應用程序中的問題的幫助。以下是我正在使用的GPSLocationListener類。FusedLocationApi方法getLastLocation（）在第一次調用期間始終爲空
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;
}
}
試着在我的實際設備上使用已在設置中啓用的GPS，我發現了一些奇怪的現象。如果我完全沒有，請致電startLocationUpdates()方法，或者我使用onRequestPermissionsResult()方法調用該方法，該應用啓動正常，當我授予設備位置權限時，mCurrentLocation對象爲空，但不會崩潰。我停止了應用程序，然後再次啓動，並且mCurrentLocation具有我可以在logcat中看到的經度和緯度座標，這是我首先想要的，但它們僅在第二次啓動後才具有任何值。現在，如果我卸載的應用，並嘗試在任何地方撥打startLocationUpdates()方法，一經推出應用程序崩潰與錯誤：
Client must have ACCESS_FINE_LOCATION permission to request PRIORITY_HIGH_ACCURACY locations.
但我檢查的onConnected()方法，並在startLocationUpdates()方法權限爲好，雖然我不認爲這是正確的，但這個是我能得到Android的工作室不強調紅色
LocationServices.FusedLocationApi.requestLocationUpdates(
mGoogleApiClient, mLocationRequest, this);
語句權限警告的唯一途徑。
這是Activity，我試圖通過mapItBtnRespond()方法獲取位置更新。
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() {
}
}
我在這裏做錯了什麼？任何幫助將不勝感激，因爲我顯然與權限混淆。非常感謝任何指導。
你爲什麼不問權限時getCurrentLocation（）方法被調用的SagActivity ？ – tahsinRupam
@tahsinRupam。我也想到了這一點，但我計劃在多個活動中使用GPS助手類，並希望一次性處理所有類中的權限請求，而不是單獨處理每個活動。 – J2112O