Bound Services

public class LocalService extends Service {    // Binder given to clients    private final IBinder mBinder = new LocalBinder();    // Random number generator    private final Random mGenerator = new Random();    /**     * Class used for the client Binder.  Because we know this service always     * runs in the same process as its clients, we don‘t need to deal with IPC.     */    public class LocalBinder extends Binder {        LocalService getService() {            // Return this instance of LocalService so clients can call public methods            return LocalService.this;        }    }    @Override    public IBinder onBind(Intent intent) {        return mBinder;    }    /** method for clients */    public int getRandomNumber() {      return mGenerator.nextInt(100);    }}

public class BindingActivity extends Activity {    LocalService mService;    boolean mBound = false;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);    }    @Override    protected void onStart() {        super.onStart();        // Bind to LocalService        Intent intent = new Intent(this, LocalService.class);        bindService(intent, mConnection, Context.BIND_AUTO_CREATE);    }    @Override    protected void onStop() {        super.onStop();        // Unbind from the service        if (mBound) {            unbindService(mConnection);            mBound = false;        }    }    /** Called when a button is clicked (the button in the layout file attaches to      * this method with the android:onClick attribute) */    public void onButtonClick(View v) {        if (mBound) {            // Call a method from the LocalService.            // However, if this call were something that might hang, then this request should            // occur in a separate thread to avoid slowing down the activity performance.            int num = mService.getRandomNumber();            Toast.makeText(this, "number: " + num, Toast.LENGTH_SHORT).show();        }    }    /** Defines callbacks for service binding, passed to bindService() */    private ServiceConnection mConnection = new ServiceConnection() {        @Override        public void onServiceConnected(ComponentName className,                IBinder service) {            // We‘ve bound to LocalService, cast the IBinder and get LocalService instance            LocalBinder binder = (LocalBinder) service;            mService = binder.getService();            mBound = true;        }        @Override        public void onServiceDisconnected(ComponentName arg0) {            mBound = false;        }    };}

public class MessengerService extends Service {    /** Command to the service to display a message */    static final int MSG_SAY_HELLO = 1;    /**     * Handler of incoming messages from clients.     */    class IncomingHandler extends Handler {        @Override        public void handleMessage(Message msg) {            switch (msg.what) {                case MSG_SAY_HELLO:                    Toast.makeText(getApplicationContext(), "hello!", Toast.LENGTH_SHORT).show();                    break;                default:                    super.handleMessage(msg);            }        }    }    /**     * Target we publish for clients to send messages to IncomingHandler.     */    final Messenger mMessenger = new Messenger(new IncomingHandler());    /**     * When binding to the service, we return an interface to our messenger     * for sending messages to the service.     */    @Override    public IBinder onBind(Intent intent) {        Toast.makeText(getApplicationContext(), "binding", Toast.LENGTH_SHORT).show();        return mMessenger.getBinder();    }}

public class ActivityMessenger extends Activity {    /** Messenger for communicating with the service. */    Messenger mService = null;    /** Flag indicating whether we have called bind on the service. */    boolean mBound;    /**     * Class for interacting with the main interface of the service.     */    private ServiceConnection mConnection = new ServiceConnection() {        public void onServiceConnected(ComponentName className, IBinder service) {            // This is called when the connection with the service has been            // established, giving us the object we can use to            // interact with the service.  We are communicating with the            // service using a Messenger, so here we get a client-side            // representation of that from the raw IBinder object.            mService = new Messenger(service);            mBound = true;        }        public void onServiceDisconnected(ComponentName className) {            // This is called when the connection with the service has been            // unexpectedly disconnected -- that is, its process crashed.            mService = null;            mBound = false;        }    };    public void sayHello(View v) {        if (!mBound) return;        // Create and send a message to the service, using a supported ‘what‘ value        Message msg = Message.obtain(null, MessengerService.MSG_SAY_HELLO, 0, 0);        try {            mService.send(msg);        } catch (RemoteException e) {            e.printStackTrace();        }    }    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);    }    @Override    protected void onStart() {        super.onStart();        // Bind to the service        bindService(new Intent(this, MessengerService.class), mConnection,            Context.BIND_AUTO_CREATE);    }    @Override    protected void onStop() {        super.onStop();        // Unbind from the service        if (mBound) {            unbindService(mConnection);            mBound = false;        }    }}