问题
I want to send data to the server periodically, I'm using background Service for that, but I want to send when the data got updated, and updated data I'm getting in Activity and the Service is running in background.. so how can i pass data to running Service from Activity. Using Intent I can send data only one time while starting the Service.
Intent serviceIntent= new Intent(DriverActivity.this,demoService.class);
serviceIntent.putExtra("token", token);
startService(serviceIntent);
回答1:
Read this article https://developer.android.com/guide/components/bound-services.html
For example you can use Messanger
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();
}
}
And in your Activity or Fragment you can send data in this way:
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;
}
}
}
If you don't know how to pass data with Message look at this answer https://stackoverflow.com/a/17929775
回答2:
The best option would be to persist the data on the hard drive (e.g. SharedPreferences, database, ...).
Activity got updated => persist to storage => invoke Service
The Service has to read the data from the chosen storage before sending the data.
回答3:
Use multithreading instead it becomes much easier and you will get the same functionality.
mHandler = new Handler();
// Set a click listener for button
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
mCounter = 0;
/*
Runnable
Represents a command that can be executed. Often used to run code in a
different Thread.
Thread
A Thread is a concurrent unit of execution. It has its own call stack for
methods being invoked, their arguments and local variables. Each application
has at least one thread running when it is started, the main thread, in the
main ThreadGroup. The runtime keeps its own threads in the system thread group.
There are two ways to execute code in a new thread. You can either subclass
Thread and overriding its run() method, or construct a new Thread and pass a
Runnable to the constructor. In either case, the start() method must be
called to actually execute the new Thread.
*/
mRunnable = new Runnable() {
/*
public abstract void run ()
Starts executing the active part of the class' code. This method is
called when a thread is started that has been created with a class which
implements Runnable.
*/
@Override
public void run() {
// Do some task on delay
doTask();
}
};
/*
public final boolean postDelayed (Runnable r, long delayMillis)
Causes the Runnable r to be added to the message queue, to be run after the
specified amount of time elapses. The runnable will be run on the thread to
which this handler is attached. The time-base is uptimeMillis(). Time spent
in deep sleep will add an additional delay to execution.
*/
mHandler.postDelayed(mRunnable, (mInterval));
}
}); //use minterval to be the period in ms eg: private int mInterval = 4000;
回答4:
1.Sending data to service Upto Lolipop edition
Intent serviceIntent= new Intent(DriverActivity.this,demoService.class);
serviceIntent.putExtra("token", token);
startService(serviceIntent);
Retrieving data in Service class :
@Override public int onStartCommand(Intent intent, int flags, int startId) { Toast.makeText(this, "Starting..", Toast.LENGTH_SHORT).show(); Log.d(APP_TAG,intent.getStringExtra("token")); return "your flag"; }
来源：https://stackoverflow.com/questions/43736714/how-to-pass-data-from-activity-to-running-service