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;
}
};
}
使用 Messenger
public class MessengerService extends Service {
/** For showing and hiding our notification. */
NotificationManager mNM;
/** Keeps track of all current registered clients. */
ArrayList<Messenger> mClients = new ArrayList<Messenger>();
/** Holds last value set by a client. */
int mValue = 0;
/**
* Command to the service to register a client, receiving callbacks
* from the service. The Message's replyTo field must be a Messenger of
* the client where callbacks should be sent.
*/
static final int MSG_REGISTER_CLIENT = 1;
/**
* Command to the service to unregister a client, ot stop receiving callbacks
* from the service. The Message's replyTo field must be a Messenger of
* the client as previously given with MSG_REGISTER_CLIENT.
*/
static final int MSG_UNREGISTER_CLIENT = 2;
/**
* Command to service to set a new value. This can be sent to the
* service to supply a new value, and will be sent by the service to
* any registered clients with the new value.
*/
static final int MSG_SET_VALUE = 3;
/**
* Handler of incoming messages from clients.
*/
class IncomingHandler extends Handler {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case MSG_REGISTER_CLIENT:
mClients.add(msg.replyTo);
break;
case MSG_UNREGISTER_CLIENT:
mClients.remove(msg.replyTo);
break;
case MSG_SET_VALUE:
mValue = msg.arg1;
for (int i=mClients.size()-1; i>=0; i--) {
try {
mClients.get(i).send(Message.obtain(null,
MSG_SET_VALUE, mValue, 0));
} catch (RemoteException e) {
// The client is dead. Remove it from the list;
// we are going through the list from back to front
// so this is safe to do inside the loop.
mClients.remove(i);
}
}
break;
default:
super.handleMessage(msg);
}
}
}
/**
* Target we publish for clients to send messages to IncomingHandler.
*/
final Messenger mMessenger = new Messenger(new IncomingHandler());
@Override
public void onCreate() {
mNM = (NotificationManager)getSystemService(NOTIFICATION_SERVICE);
// Display a notification about us starting.
showNotification();
}
@Override
public void onDestroy() {
// Cancel the persistent notification.
mNM.cancel(R.string.remote_service_started);
// Tell the user we stopped.
Toast.makeText(this, R.string.remote_service_stopped, Toast.LENGTH_SHORT).show();
}
/**
* When binding to the service, we return an interface to our messenger
* for sending messages to the service.
*/
@Override
public IBinder onBind(Intent intent) {
return mMessenger.getBinder();
}
/**
* Show a notification while this service is running.
*/
private void showNotification() {
// In this sample, we'll use the same text for the ticker and the expanded notification
CharSequence text = getText(R.string.remote_service_started);
// The PendingIntent to launch our activity if the user selects this notification
PendingIntent contentIntent = PendingIntent.getActivity(this, 0,
new Intent(this, RemoteService.Controller.class), 0);
// Set the info for the views that show in the notification panel.
Notification notification = new Notification.Builder(this)
.setSmallIcon(R.drawable.stat_sample) // the status icon
.setTicker(text) // the status text
.setWhen(System.currentTimeMillis()) // the time stamp
.setContentTitle(getText(R.string.local_service_label)) // the label of the entry
.setContentText(text) // the contents of the entry
.setContentIntent(contentIntent) // The intent to send when the entry is clicked
.build();
// Send the notification.
// We use a string id because it is a unique number. We use it later to cancel.
mNM.notify(R.string.remote_service_started, notification);
}
}
//END_INCLUDE(service)
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;
}
}
}
