Ejemplo: comunicación entre actividad y servicio mediante mensajería
No pude encontrar ningún ejemplo de cómo enviar mensajes entre una actividad y un servicio, y pasé demasiadas horas resolviendo esto. Aquí hay un proyecto de ejemplo para que otros puedan consultarlo.
Este ejemplo le permite iniciar o detener un servicio directamente y vincularlo o desvincularlo por separado. Cuando el servicio se está ejecutando, incrementa un número a 10 Hz. Si la actividad está vinculada a Service, mostrará el valor actual. Los datos se transfieren como un número entero y como una cadena, por lo que puedes ver cómo hacerlo de dos maneras diferentes. También hay botones en la actividad para enviar mensajes al servicio (cambia el valor de incremento).
Captura de pantalla:
AndroidManifest.xml:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.exampleservice"
android:versionCode="1"
android:versionName="1.0">
<application android:icon="@drawable/icon" android:label="@string/app_name">
<activity android:name=".MainActivity"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<service android:name=".MyService"></service>
</application>
<uses-sdk android:minSdkVersion="8" />
</manifest>
res\valores\cadenas.xml:
<?xml version="1.0" encoding="utf-8"?>
<resources>
<string name="app_name">ExampleService</string>
<string name="service_started">Example Service started</string>
<string name="service_label">Example Service Label</string>
</resources>
res\diseño\main.xml:
<RelativeLayout
android:id="@+id/RelativeLayout01"
android:layout_width="fill_parent"
android:layout_height="wrap_content" >
<Button
android:id="@+id/btnStart"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Start Service" >
</Button>
<Button
android:id="@+id/btnStop"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:text="Stop Service" >
</Button>
</RelativeLayout>
<RelativeLayout
android:id="@+id/RelativeLayout02"
android:layout_width="fill_parent"
android:layout_height="wrap_content" >
<Button
android:id="@+id/btnBind"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Bind to Service" >
</Button>
<Button
android:id="@+id/btnUnbind"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:text="Unbind from Service" >
</Button>
</RelativeLayout>
<TextView
android:id="@+id/textStatus"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Status Goes Here"
android:textSize="24sp" />
<TextView
android:id="@+id/textIntValue"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Integer Value Goes Here"
android:textSize="24sp" />
<TextView
android:id="@+id/textStrValue"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="String Value Goes Here"
android:textSize="24sp" />
<RelativeLayout
android:id="@+id/RelativeLayout03"
android:layout_width="fill_parent"
android:layout_height="wrap_content" >
<Button
android:id="@+id/btnUpby1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Increment by 1" >
</Button>
<Button
android:id="@+id/btnUpby10"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:text="Increment by 10" >
</Button>
</RelativeLayout>
src\com.exampleservice\MainActivity.java:
package com.exampleservice;
import android.app.Activity;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.Handler;
import android.os.IBinder;
import android.os.Message;
import android.os.Messenger;
import android.os.RemoteException;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
public class MainActivity extends Activity {
Button btnStart, btnStop, btnBind, btnUnbind, btnUpby1, btnUpby10;
TextView textStatus, textIntValue, textStrValue;
Messenger mService = null;
boolean mIsBound;
final Messenger mMessenger = new Messenger(new IncomingHandler());
class IncomingHandler extends Handler {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case MyService.MSG_SET_INT_VALUE:
textIntValue.setText("Int Message: " + msg.arg1);
break;
case MyService.MSG_SET_STRING_VALUE:
String str1 = msg.getData().getString("str1");
textStrValue.setText("Str Message: " + str1);
break;
default:
super.handleMessage(msg);
}
}
}
private ServiceConnection mConnection = new ServiceConnection() {
public void onServiceConnected(ComponentName className, IBinder service) {
mService = new Messenger(service);
textStatus.setText("Attached.");
try {
Message msg = Message.obtain(null, MyService.MSG_REGISTER_CLIENT);
msg.replyTo = mMessenger;
mService.send(msg);
}
catch (RemoteException e) {
// In this case the service has crashed before we could even do anything with it
}
}
public void onServiceDisconnected(ComponentName className) {
// This is called when the connection with the service has been unexpectedly disconnected - process crashed.
mService = null;
textStatus.setText("Disconnected.");
}
};
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
btnStart = (Button)findViewById(R.id.btnStart);
btnStop = (Button)findViewById(R.id.btnStop);
btnBind = (Button)findViewById(R.id.btnBind);
btnUnbind = (Button)findViewById(R.id.btnUnbind);
textStatus = (TextView)findViewById(R.id.textStatus);
textIntValue = (TextView)findViewById(R.id.textIntValue);
textStrValue = (TextView)findViewById(R.id.textStrValue);
btnUpby1 = (Button)findViewById(R.id.btnUpby1);
btnUpby10 = (Button)findViewById(R.id.btnUpby10);
btnStart.setOnClickListener(btnStartListener);
btnStop.setOnClickListener(btnStopListener);
btnBind.setOnClickListener(btnBindListener);
btnUnbind.setOnClickListener(btnUnbindListener);
btnUpby1.setOnClickListener(btnUpby1Listener);
btnUpby10.setOnClickListener(btnUpby10Listener);
restoreMe(savedInstanceState);
CheckIfServiceIsRunning();
}
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putString("textStatus", textStatus.getText().toString());
outState.putString("textIntValue", textIntValue.getText().toString());
outState.putString("textStrValue", textStrValue.getText().toString());
}
private void restoreMe(Bundle state) {
if (state!=null) {
textStatus.setText(state.getString("textStatus"));
textIntValue.setText(state.getString("textIntValue"));
textStrValue.setText(state.getString("textStrValue"));
}
}
private void CheckIfServiceIsRunning() {
//If the service is running when the activity starts, we want to automatically bind to it.
if (MyService.isRunning()) {
doBindService();
}
}
private OnClickListener btnStartListener = new OnClickListener() {
public void onClick(View v){
startService(new Intent(MainActivity.this, MyService.class));
}
};
private OnClickListener btnStopListener = new OnClickListener() {
public void onClick(View v){
doUnbindService();
stopService(new Intent(MainActivity.this, MyService.class));
}
};
private OnClickListener btnBindListener = new OnClickListener() {
public void onClick(View v){
doBindService();
}
};
private OnClickListener btnUnbindListener = new OnClickListener() {
public void onClick(View v){
doUnbindService();
}
};
private OnClickListener btnUpby1Listener = new OnClickListener() {
public void onClick(View v){
sendMessageToService(1);
}
};
private OnClickListener btnUpby10Listener = new OnClickListener() {
public void onClick(View v){
sendMessageToService(10);
}
};
private void sendMessageToService(int intvaluetosend) {
if (mIsBound) {
if (mService != null) {
try {
Message msg = Message.obtain(null, MyService.MSG_SET_INT_VALUE, intvaluetosend, 0);
msg.replyTo = mMessenger;
mService.send(msg);
}
catch (RemoteException e) {
}
}
}
}
void doBindService() {
bindService(new Intent(this, MyService.class), mConnection, Context.BIND_AUTO_CREATE);
mIsBound = true;
textStatus.setText("Binding.");
}
void doUnbindService() {
if (mIsBound) {
// If we have received the service, and hence registered with it, then now is the time to unregister.
if (mService != null) {
try {
Message msg = Message.obtain(null, MyService.MSG_UNREGISTER_CLIENT);
msg.replyTo = mMessenger;
mService.send(msg);
}
catch (RemoteException e) {
// There is nothing special we need to do if the service has crashed.
}
}
// Detach our existing connection.
unbindService(mConnection);
mIsBound = false;
textStatus.setText("Unbinding.");
}
}
@Override
protected void onDestroy() {
super.onDestroy();
try {
doUnbindService();
}
catch (Throwable t) {
Log.e("MainActivity", "Failed to unbind from the service", t);
}
}
}
src\com.exampleservice\MyService.java:
package com.exampleservice;
import java.util.ArrayList;
import java.util.Timer;
import java.util.TimerTask;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.app.Service;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.os.IBinder;
import android.os.Message;
import android.os.Messenger;
import android.os.RemoteException;
import android.util.Log;
public class MyService extends Service {
private NotificationManager nm;
private Timer timer = new Timer();
private int counter = 0, incrementby = 1;
private static boolean isRunning = false;
ArrayList<Messenger> mClients = new ArrayList<Messenger>(); // Keeps track of all current registered clients.
int mValue = 0; // Holds last value set by a client.
static final int MSG_REGISTER_CLIENT = 1;
static final int MSG_UNREGISTER_CLIENT = 2;
static final int MSG_SET_INT_VALUE = 3;
static final int MSG_SET_STRING_VALUE = 4;
final Messenger mMessenger = new Messenger(new IncomingHandler()); // Target we publish for clients to send messages to IncomingHandler.
@Override
public IBinder onBind(Intent intent) {
return mMessenger.getBinder();
}
class IncomingHandler extends Handler { // Handler of incoming messages from clients.
@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_INT_VALUE:
incrementby = msg.arg1;
break;
default:
super.handleMessage(msg);
}
}
}
private void sendMessageToUI(int intvaluetosend) {
for (int i=mClients.size()-1; i>=0; i--) {
try {
// Send data as an Integer
mClients.get(i).send(Message.obtain(null, MSG_SET_INT_VALUE, intvaluetosend, 0));
//Send data as a String
Bundle b = new Bundle();
b.putString("str1", "ab" + intvaluetosend + "cd");
Message msg = Message.obtain(null, MSG_SET_STRING_VALUE);
msg.setData(b);
mClients.get(i).send(msg);
}
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);
}
}
}
@Override
public void onCreate() {
super.onCreate();
Log.i("MyService", "Service Started.");
showNotification();
timer.scheduleAtFixedRate(new TimerTask(){ public void run() {onTimerTick();}}, 0, 100L);
isRunning = true;
}
private void showNotification() {
nm = (NotificationManager)getSystemService(NOTIFICATION_SERVICE);
// In this sample, we'll use the same text for the ticker and the expanded notification
CharSequence text = getText(R.string.service_started);
// Set the icon, scrolling text and timestamp
Notification notification = new Notification(R.drawable.icon, text, System.currentTimeMillis());
// The PendingIntent to launch our activity if the user selects this notification
PendingIntent contentIntent = PendingIntent.getActivity(this, 0, new Intent(this, MainActivity.class), 0);
// Set the info for the views that show in the notification panel.
notification.setLatestEventInfo(this, getText(R.string.service_label), text, contentIntent);
// Send the notification.
// We use a layout id because it is a unique number. We use it later to cancel.
nm.notify(R.string.service_started, notification);
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.i("MyService", "Received start id " + startId + ": " + intent);
return START_STICKY; // run until explicitly stopped.
}
public static boolean isRunning()
{
return isRunning;
}
private void onTimerTick() {
Log.i("TimerTick", "Timer doing work." + counter);
try {
counter += incrementby;
sendMessageToUI(counter);
}
catch (Throwable t) { //you should always ultimately catch all exceptions in timer tasks.
Log.e("TimerTick", "Timer Tick Failed.", t);
}
}
@Override
public void onDestroy() {
super.onDestroy();
if (timer != null) {timer.cancel();}
counter=0;
nm.cancel(R.string.service_started); // Cancel the persistent notification.
Log.i("MyService", "Service Stopped.");
isRunning = false;
}
}
Aceptado
Mire el ejemplo de LocalService .
Su Servicedevuelve una instancia de sí mismo a los consumidores que llaman onBind. Luego podrá interactuar directamente con el servicio, por ejemplo, registrando su propia interfaz de escucha en el servicio, para poder recibir devoluciones de llamadas.
Para enviar datos a un servicio puede utilizar:
Intent intent = new Intent(getApplicationContext(), YourService.class);
intent.putExtra("SomeData","ItValue");
startService(intent);
Y después de estar en servicio en onStartCommand(), obtenga datos de la intención.
Para enviar datos o eventos desde un servicio a una aplicación (para una o más actividades):
private void sendBroadcastMessage(String intentFilterName, int arg1, String extraKey) {
Intent intent = new Intent(intentFilterName);
if (arg1 != -1 && extraKey != null) {
intent.putExtra(extraKey, arg1);
}
sendBroadcast(intent);
}
Este método llama desde su servicio. Simplemente puede enviar datos para su Actividad.
private void someTaskInYourService(){
//For example you downloading from server 1000 files
for(int i = 0; i < 1000; i++) {
Thread.sleep(5000) // 5 seconds. Catch in try-catch block
sendBroadCastMessage(Events.UPDATE_DOWNLOADING_PROGRESSBAR, i,0,"up_download_progress");
}
Para recibir un evento con datos, cree y registre el método RegisterBroadcastReceivers() en su actividad:
private void registerBroadcastReceivers(){
broadcastReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
int arg1 = intent.getIntExtra("up_download_progress",0);
progressBar.setProgress(arg1);
}
};
IntentFilter progressfilter = new IntentFilter(Events.UPDATE_DOWNLOADING_PROGRESS);
registerReceiver(broadcastReceiver,progressfilter);
Para enviar más datos, puede modificar el método sendBroadcastMessage();. Recuerde: ¡debe registrar transmisiones en onResume() y cancelar el registro en los métodos onStop()!
ACTUALIZAR
No utilice mi tipo de comunicación entre Actividad y Servicio. Éste es el camino equivocado. Para una mejor experiencia, utilice bibliotecas especiales, como por ejemplo:
1) EventBus de greenrobot
2) Otto de Square Inc.
PD: solo estoy usando EventBus de greenrobot en mis proyectos.
Nota: No necesita verificar si su servicio se está ejecutando, CheckIfServiceIsRunning()porque bindService()lo iniciará si no se está ejecutando.
Además: si giras el teléfono no quieres que lo bindService()vuelva a hacer, porque onCreate()te volverán a llamar. Asegúrese de definirlo onConfigurationChanged()para evitar esto.
