java - 为什么我不能从我的 Activity 中调用此服务？

Question

我试过以两种不同的方式调用此服务，但似乎没有用。

第一种方式是:

startService(new Intent(getBaseContext(), LocationService.class));

为此我收到一条错误信息`

引起:`java.lang.IllegalStateException:GoogleApiClient 尚未连接。

然后我尝试了这个:

Intent serviceIntent = new Intent();
                serviceIntent.setAction("com.parseapp.eseen.eseen.service.LocationService");
                startService(serviceIntent);

它也没有用，相反绝对没有任何反应，logcat 中没有任何显示。谁能帮忙？完整代码如下:

LocationService.class

public class LocationService extends Service implements GoogleApiClient.ConnectionCallbacks,
    GoogleApiClient.OnConnectionFailedListener, LocationListener {

// LogCat tag
private static final String TAG = LocationService.class.getSimpleName();

private final static int PLAY_SERVICES_RESOLUTION_REQUEST = 1000;

private Location mLastLocation;

// Google client to interact with Google API
private GoogleApiClient mGoogleApiClient;

// boolean flag to toggle periodic location updates
private boolean mRequestingLocationUpdates = false;

private LocationRequest mLocationRequest;

// Location updates intervals in sec
private static int UPDATE_INTERVAL = 10000; // 10 sec
private static int FATEST_INTERVAL = 5000; // 5 sec
private static int DISPLACEMENT = 10; // 10 meters


@Override
public void onCreate() {
    super.onCreate();

    mGoogleApiClient = new GoogleApiClient.Builder(this)
            .addConnectionCallbacks(this)
            .addOnConnectionFailedListener(this)
            .addApi(LocationServices.API).build();


}

@Override
public int onStartCommand(Intent intent, int flags, int startId) {

    if (mGoogleApiClient != null) {
        mGoogleApiClient.connect();
        togglePeriodicLocationUpdates();
    }



    return START_NOT_STICKY;
}

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

protected void createLocationRequest() {
    mLocationRequest = new LocationRequest();
    mLocationRequest.setInterval(UPDATE_INTERVAL);
    mLocationRequest.setFastestInterval(FATEST_INTERVAL);
    mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
    mLocationRequest.setSmallestDisplacement(DISPLACEMENT);
}

private void togglePeriodicLocationUpdates() {
    mGoogleApiClient.connect();

    if (!mRequestingLocationUpdates) {

        mRequestingLocationUpdates = true;

        startLocationUpdates();

        Log.d(TAG, "Periodic location updates started!");

    } else {

        mRequestingLocationUpdates = false;

        // Stopping the location updates
        stopLocationUpdates();

        Log.d(TAG, "Periodic location updates stopped!");
    }
}

protected void stopLocationUpdates() {
    LocationServices.FusedLocationApi.removeLocationUpdates(
            mGoogleApiClient, this);
}

protected void startLocationUpdates() {
    mGoogleApiClient.connect();
    LocationServices.FusedLocationApi.requestLocationUpdates(
            mGoogleApiClient, mLocationRequest, this);

}

@Override
public void onConnected(Bundle arg0) {
    createLocationRequest();
}

@Override
public void onConnectionSuspended(int arg0) {
    mGoogleApiClient.connect();
}

@Override
public void onConnectionFailed(ConnectionResult result) {
    Log.i(TAG, "Connection failed: ConnectionResult.getErrorCode() = "
            + result.getErrorCode());
}

@Override
public void onLocationChanged(Location location) {
    // Assign the new location
    mLastLocation = location;

    Toast.makeText(getApplicationContext(), "Location changed!",
            Toast.LENGTH_SHORT).show();
}

@Override
public boolean stopService(Intent name) {
    return super.stopService(name);
}

SearchActivity.class

button = (Button)findViewById(R.id.buttonPressed);
    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent serviceIntent = new Intent();
            serviceIntent.setAction("com.parseapp.eseen.eseen.service.LocationService");
            startService(serviceIntent);
        }
    });

AndroidManifest.xml

<service android:name=".LocationService">

        <intent-filter>
            <action android:name=".LocationService"> </action>
        </intent-filter>

    </service>

   

Answer 1

您第一次尝试使用类名启动服务成功了:

startService(new Intent(getBaseContext(), LocationService.class));

异常发生在服务开始执行后。在 GoogleApi 连接成功之前，即在调用 onConnected() 之后，您的代码无法使用 LocationServices。您的代码在到达 startLocationUpdates() 之前多次调用 connect()，但不等待调用 onConnected()。该方法是您在建立连接并且可以使用 LocationServices 时收到的通知。

这demo code适用于 AsyncTask，而不是服务，但给出了如何使用 CountDownLatch 完成连接处理的想法。