Question

如何将此活动修改为服务，我希望能够从另一个活动中调用此服务，并且即使用户实际上不在应用中，也能够在后台工作。当我尝试将其转换为服务时，我遇到了onResume（），onStart（），onStop（）和finish（）的问题。我该如何解决这个问题？这是作为活动的代码：

public class MainActivity extends Activity implements ConnectionCallbacks,
    OnConnectionFailedListener, LocationListener {

// LogCat tag
private static final String TAG = MainActivity.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

// UI elements
private TextView lblLocation;
private Button btnShowLocation, btnStartLocationUpdates;

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

    lblLocation = (TextView) findViewById(R.id.lblLocation);
    btnShowLocation = (Button) findViewById(R.id.btnShowLocation);
    btnStartLocationUpdates = (Button) findViewById(R.id.btnLocationUpdates);

    // First we need to check availability of play services
    if (checkPlayServices()) {

        // Building the GoogleApi client
        buildGoogleApiClient();

        createLocationRequest();
    }

    // Show location button click listener
    btnShowLocation.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            displayLocation();
        }
    });

    // Toggling the periodic location updates
    btnStartLocationUpdates.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            togglePeriodicLocationUpdates();
        }
    });

}

@Override
protected void onStart() {
    super.onStart();
    if (mGoogleApiClient != null) {
        mGoogleApiClient.connect();
    }
}

@Override
protected void onResume() {
    super.onResume();

    checkPlayServices();

    // Resuming the periodic location updates
    if (mGoogleApiClient.isConnected() && mRequestingLocationUpdates) {
        startLocationUpdates();
    }
}

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

@Override
protected void onPause() {
    super.onPause();
    stopLocationUpdates();
}

/**
 * Method to display the location on UI
 * */
private void displayLocation() {

    mLastLocation = LocationServices.FusedLocationApi
            .getLastLocation(mGoogleApiClient);

    if (mLastLocation != null) {
        double latitude = mLastLocation.getLatitude();
        double longitude = mLastLocation.getLongitude();

        lblLocation.setText(latitude + ", " + longitude);

    } else {

        lblLocation
                .setText("(Couldn't get the location. Make sure location is enabled on the device)");
    }
}

/**
 * Method to toggle periodic location updates
 * */
private void togglePeriodicLocationUpdates() {
    if (!mRequestingLocationUpdates) {
        // Changing the button text
        btnStartLocationUpdates
                .setText(getString(R.string.btn_stop_location_updates));

        mRequestingLocationUpdates = true;

        // Starting the location updates
        startLocationUpdates();

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

    } else {
        // Changing the button text
        btnStartLocationUpdates
                .setText(getString(R.string.btn_start_location_updates));

        mRequestingLocationUpdates = false;

        // Stopping the location updates
        stopLocationUpdates();

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

/**
 * Creating google api client object
 * */
protected synchronized void buildGoogleApiClient() {
    mGoogleApiClient = new GoogleApiClient.Builder(this)
            .addConnectionCallbacks(this)
            .addOnConnectionFailedListener(this)
            .addApi(LocationServices.API).build();
}

/**
 * Creating location request object
 * */
protected void createLocationRequest() {
    mLocationRequest = new LocationRequest();
    mLocationRequest.setInterval(UPDATE_INTERVAL);
    mLocationRequest.setFastestInterval(FATEST_INTERVAL);
    mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
    mLocationRequest.setSmallestDisplacement(DISPLACEMENT);
}

/**
 * Method to verify google play services on the device
 * */
private boolean checkPlayServices() {
    int resultCode = GooglePlayServicesUtil
            .isGooglePlayServicesAvailable(this);
    if (resultCode != ConnectionResult.SUCCESS) {
        if (GooglePlayServicesUtil.isUserRecoverableError(resultCode)) {
            GooglePlayServicesUtil.getErrorDialog(resultCode, this,
                    PLAY_SERVICES_RESOLUTION_REQUEST).show();
        } else {
            Toast.makeText(getApplicationContext(),
                    "This device is not supported.", Toast.LENGTH_LONG)
                    .show();
            finish();
        }
        return false;
    }
    return true;
}

/**
 * Starting the location updates
 * */
protected void startLocationUpdates() {

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

}

/**
 * Stopping location updates
 */
protected void stopLocationUpdates() {
    LocationServices.FusedLocationApi.removeLocationUpdates(
            mGoogleApiClient, this);
}

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

@Override
public void onConnected(Bundle arg0) {

    // Once connected with google api, get the location
    displayLocation();

    if (mRequestingLocationUpdates) {
        startLocationUpdates();
    }
}

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

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

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

    // Displaying the new location on UI
    displayLocation();
}

Answer 1

您需要阅读服务。他们有不同的生命周期。完成不存在。 OnPause，OnResume等不存在。生命周期在http://developer.android.com/reference/android/app/Service.html解释。从那里开始阅读。

使Activity中的代码变成服务困难

1 个答案: