I've already bound an activity to my service following this tutorial.
http://developer.android.com/guide/components/bound-services.html
I'm able to call service functions, but what if I want to for example, change some of my textviews or disable some of the toggle buttons because of work done on the service (and from the service). Would there be an easy to way to do this?
You can use messages to send information between activities and services. This is an easy way to send simple data, but may not be the best option if you need to send data very frequently, or send complicated data. This is an example of some code I have in one of my apps with a service and an activity which communicate:
Code in the activity:
//this is where you set what you want to happen
class IncomingHandler extends Handler {
#Override
public void handleMessage(Message msg) {
switch (msg.what) {
//this switch reads the information in the message (usually just
//an integer) and will do something depending on which integer is sent
case 1: do_something();
case 2: do_something_2(); //etc.
default:
super.handleMessage(msg);
}
}
}
final Messenger myMessenger = new Messenger(new IncomingHandler());
private ServiceConnection mConnection = new ServiceConnection() {
public void onServiceConnected(ComponentName className,
IBinder service) {
myService = new Messenger(service);
myCallbackText = (TextView)findViewById(R.id.tv01); //This is a text view which will display status information as needed
myCallbackText.setText("Attached.");
try {
Message msg = Message.obtain(null,
1);
msg.replyTo = mMessenger; //here we send an instance of our messenger implementation as the replyTo address
mService.send(msg);
msg = Message.obtain(null,
3, this.hashCode(), 0);
mService.send(msg); //send a message with the value "3"
} catch (RemoteException e) {
//nothing you can do if the server isn't active
}
Toast.makeText(Service_testActivity.this, R.string.remote_service_connected,
Toast.LENGTH_SHORT).show();//confirmation that the connection happened successfully
}
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;
mCallbackText = (TextView)findViewById(R.id.tv01);//same textview as before
mCallbackText.setText("Disconnected.");
Toast.makeText(Service_testActivity.this, R.string.remote_service_disconnected,
Toast.LENGTH_SHORT).show();
}
};
Code in the service:
In the service, you will want to have code (very similar to the code in the activity) to receive a message and save the msg.replyTo field as a Messenger object. There is an example somewhere which will have you make an object and then use an IncomingHandler like this:
ArrayList<Messenger> mClients = new ArrayList<Messenger>();
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;
default:
super.handleMessage(msg);
}
}
}
This can allow your service to keep track of multiple clients at once and send messages to specified clients. To send a message simply use something like this:
mClients.get(1).send(Message.obtain(null, 3, new Random().nextInt(), 0));
//sends a message to the first client saved in the list
Related
I have been stuck with one problem. I need some people which check a part of my code and help me with problem and critize my code (I write code but I haven't people which can say this is wrong or something in this pattern)
Generally.
My service get message from bluetooth (HC-05) and I can see values in Log.d, in service.
A part code of my service which get message.
private class ConnectedThread extends Thread{
private final BluetoothSocket bluetoothSocket;
private final InputStream inputStream;
private final OutputStream outputStream;
public ConnectedThread(BluetoothSocket socket){
Log.d(TAG,"ConnectedThread: Starting");
bluetoothSocket=socket;
InputStream tmpInput = null;
OutputStream tmpOutput = null;
try{
tmpInput = bluetoothSocket.getInputStream();
tmpOutput = bluetoothSocket.getOutputStream();
}catch (IOException e){
e.printStackTrace();
active=false;
}
inputStream=tmpInput;
outputStream=tmpOutput;
}
#Override
public void run() {
byte[] buffer = new byte[1024];
int bytes;
while(active){
try {
bytes = inputStream.read(buffer);
final String comingMsg = new String(buffer,0,bytes);
Log.d(TAG,"InputStream: " + comingMsg);
new Handler(Looper.getMainLooper()).post(new Runnable() {
#Override
public void run() {
Message message = new Message();
message.obj = comingMsg;
message.what = 1; // I need it to prevent NullObjReference
Log.d(TAG,"Handler run(): " + message.obj);
mHandler.sendMessage(message);
}
});
}catch (IOException e){
Log.e(TAG,"Write: Error reading input." + e.getMessage());
active=false;
break;
}
}
}
...some code is hidden because it is diploma thesis
}
The problem is get message every time from this service to another activity where all is happen.
I tried a lot of things (with Threads,Looper,runOnUiThread, handleMessage and callback), checked a lot of posts in stackoverflow and I tried to combine with my project but all time I had nullobjectreference (for that i tried to use msg.what to check) , black screen when tried to move to my home activity (it is main) and update my textView or typical crash app.
Now I want only to get message from service to textview. When everything starts working fine, I want to parse string (for example 3 first chars) and send message to one of six textviews.
A part of codes from onCreate before method runThread() is started:
Log.d(TAG,"Check intent - result");
if(getIntent().getIntExtra("result",0)==RESULT_OK){
mDevice = getIntent().getExtras().getParcelable("bonded device");
startConnection(mDevice,MY_UUID);
Log.d(TAG,"Check is active service ");
checkIfActive();;
}
Log.d(TAG,"Check intent - connect_to_paired");
if(getIntent().getIntExtra("connect_to_paired",0)==RESULT_OK){
mDevice = getIntent().getExtras().getParcelable("bonded_paired_device");
startConnection(mDevice,MY_UUID);
Log.d(TAG,"Check is active service ");
checkIfActive();
}
public void checkIfActive(){
Log.d(TAG,"CheckIfActive: Started");
while(myBluetoothService.active!=true) {
Log.d(TAG,"CheckIfActive() active is "+ myBluetoothService.active);
if (myBluetoothService.active) {
Log.d(TAG, "CheckIfActive: Running method runOnUiThread - myBluetoothService.active is "+myBluetoothService.active);
runThread();
}
}
}
Method runThread() which should work everytime after connected with bluetooth device:
public void runThread(){
//I used there Thread but when connection was fail,
// method created multiply threads when I tried to connect next time
runOnUiThread(new Runnable() {
#Override
public void run() {
handler = new Handler(Looper.getMainLooper()){
#Override
public void handleMessage(Message msg) {
while (true) {
switch (msg.what) {
//when is one, service has messages to send
case 1:
String message = myBluetoothService.mHandler.obtainMessage().toString();
rearLeft.setText(message);
break;
default:
super.handleMessage(msg);
}
}
}
};
}
});
}
UPDATE:
Is it good idea ? Maybe I can put JSON Object to service to send message and in the HomeActivity, I can try get values from JSON. Is it fast ? I send a lot of data, because bluetooth receive data of distance from 4 ultrasound sensors in 4 times in lasts until few milliseconds, everytime.
Here is screen how sees my data in service when I have debug logs.
Next idea, but still nothing:
HomeActivity (my main)
public void runThread(){
runOnUiThread(new Runnable() {
#Override
public void run() {
//Looper.prepare();
new Handler() {
#Override
public void handleMessage(Message msg) {
rearLeft.setText(msg.obj.toString());
}
};
//Looper.loop();
//Log.d(TAG, myBluetoothService.mHandler.getLooper().toString());
//rearLeft.setText(myBluetoothService.mHandler.getLooper().toString());
}
});
}
Service which should send data from bluetooth to UI Thread is the same (Check first code).
Screen from HomeActivity where you can see 6 text views. Now I want put all text to one view which will be refresh by get next message.
Ok this post a bit help me to solve problem:
Sending a simple message from Service to Activity
Maybe this link could help another people.
Thanks for help, now understand why i should use broadcast receiver to do this.
Hi I make Android application for Xamarin. I have created a simple application in the Android studio. so any answer welcome either Java or C#
I have a service(GPS service) and 2 Activities.
MainActivity - GPS service are well connected with the broadcast. I hope MainActivity -> Another activity real time GPS point.(It is also okay to send from the GPS service to another activity.) but it is fail...app is dead..
MainActivity code
private void RegisterService()
{
_gpsServiceConnection = new GPSServiceConnection(_binder);
_gpsServiceIntent = new Intent(Android.App.Application.Context, typeof(GPS.GPSService));
BindService(_gpsServiceIntent, _gpsServiceConnection, Bind.AutoCreate);
}
private void RegisterBroadcastReceiver()
{
IntentFilter filter = new IntentFilter(GPSServiceReciever.LOCATION_UPDATED);
filter.AddCategory(Intent.CategoryDefault);
_receiver = new GPSServiceReciever();
RegisterReceiver(_receiver, filter);
}
private void UnRegisterBroadcastReceiver()
{
UnregisterReceiver(_receiver);
}
public void UpdateUI(Intent intent)
{
LatLng_txt.Text = intent.GetStringExtra("Location");
Lat = intent.GetDoubleExtra("Lat", 0.0);
Lng = intent.GetDoubleExtra("Lng", 0.0);
}
protected override void OnResume()
{
base.OnResume();
RegisterBroadcastReceiver();
}
protected override void OnPause()
{
base.OnPause();
UnRegisterBroadcastReceiver();
}
[BroadcastReceiver]
internal class GPSServiceReciever : BroadcastReceiver
{
public static readonly string LOCATION_UPDATED = "LOCATION_UPDATED";
public override void OnReceive(Context context, Intent intent)
{
if (intent.Action.Equals(LOCATION_UPDATED))
{
Instance.UpdateUI(intent);
}
}
}
GPS Service code
public void OnLocationChanged(Location location)
{
try
{
_currentLocation = location;
if (_currentLocation == null)
{
_location = "Unable to determine your location.";
}
else
{
_location = String.Format("{0}, {1}", _currentLocation.Latitude, _currentLocation.Longitude);
Geocoder geocoder = new Geocoder(this);
IList<Address> addressList = geocoder.GetFromLocation(_currentLocation.Latitude,
_currentLocation.Longitude, 10);
Address addressCurrent = addressList.FirstOrDefault();
if (addressCurrent != null)
{
StringBuilder deviceAddress = new StringBuilder();
for (int i = 0; i < addressCurrent.MaxAddressLineIndex; i++)
{
deviceAddress.Append(addressCurrent.GetAddressLine(i)).AppendLine(",");
}
_address = deviceAddress.ToString();
}
else
{
_address = "Unable to determine the address.";
}
IList<Address> source = geocoder.GetFromLocationName(_sourceAddress, 1);
Address addressOrigin = source.FirstOrDefault();
var coord1 = new LatLng(addressOrigin.Latitude, addressOrigin.Longitude);
var coord2 = new LatLng(addressCurrent.Latitude, addressCurrent.Longitude);
var distanceInRadius = Utils.HaversineDistance(coord1, coord2, Utils.DistanceUnit.Miles);
_remarks = string.Format("Your are {0} miles away from your original location.", distanceInRadius);
Intent intent = new Intent(this, typeof(MainActivity.GPSServiceReciever));
intent.SetAction(MainActivity.GPSServiceReciever.LOCATION_UPDATED);
intent.AddCategory(Intent.CategoryDefault);
intent.PutExtra("Location", _location);
intent.PutExtra("Lat", _currentLocation.Latitude);
intent.PutExtra("Lng", _currentLocation.Longitude);
SendBroadcast(intent);
}
}
catch
{
_address = "Unable to determine the address.";
}
}
Is not there a good way?
I understood your problem.But dont know more about GPS etc.I have faced the same problem when I was creating Music App.
Two activities were there and one service.And successfully got real time song position and song data from both activities.
My MainActivity has
ServiceConnection sc=null;
public static PlayerService ps;
And gets its value in onCreate of MainActivity
sc=new ServiceConnection(){
#Override
public void onServiceConnected(ComponentName p1, IBinder p2)
{
PlayerService.Getters getters=(PlayerService.Getters) p2;
ps=getters.getService();
}
#Override
public void onServiceDisconnected(ComponentName p1)
{
// TODO: Implement this method
}
};
Then PlayerService.Getters class is
public class Getters extends Binder
{
public PlayerService getService()
{
return PlayerService.this;
}
}
PlayerService has
#Override
public IBinder onBind(Intent p1)
{
return new Getters();
}
getService of Getters gives the object of PlayerService to my MainActivity.
Now I can get real time values of service variables and methods using static ps from multiple activities.
In order to send data or information from Service to Activity, you'll need to use Messenger API. This API will allow you to create an inter process communication (IPC) i.e. a communication link between two or more processes. In Android, Activity and Service are two separate processes, so you can use the IPC technique to establish a communication link in between them.
In the IPC technique, there are two ends, the Server end and the Client end. The Service acts as the Server and Activity acts as the Client.
Note: Service will only be able to communicate with one Activity at a time.
Messenger allows for the implementation of message-based communication across processes by help of Handlers.
Handler is a that allows you to send and process these messages.
Steps for implementing a Messenger:
Step 1. Service implements a Handler which receives the callbacks from the Activity
Step 2. The Handler then creates a Messenger object which further on creates an IBinder that the Service returns to the Activity.
Step 3. Activity then uses the IBinder to instantiate the Messenger, which the Activity uses to send messages to the Service.
Step 4. The Service receives the messages in the Handler created in the 1st step.
Lets now understand it with an example:
Create a Handler in the Service like this:
class ServiceHandler extends Handler {
#Override
public void handleMessage(Message msg) {
switch (msg.what) {
default:
super.handleMessage(msg);
}
}
}
Now, add the Messenger object along with onBind() method to the Service as mentioned in 2nd step above:
final Messenger messenger = new Messenger(new ServiceHandler());
#Override
public IBinder onBind(Intent intent) {
return messenger.getBinder();
}
In the Activity, we will create a ServiceConnection to fetch the iBinder from the Service to instantiate the Messenger object as mentioned in the 3rd step above.
Messenger messenger;
private ServiceConnection serviceConnection = new ServiceConnection() {
public void onServiceConnected(ComponentName className, IBinder iBinder) {
messenger = new Messenger(iBinder);
}
public void onServiceDisconnected(ComponentName className) {
}
};
Bind the Service to the Activity by help of the ServiceConnection created above:
bindService(new Intent(this, MessengerService.class), serviceConnection,
Context.BIND_AUTO_CREATE);
To send messages to the Service from the Activity, use the send() method of the Messenger object.
If you want to receive messages from the Service in the Activity, you need to create a Messenger in the Activity along with a Handler and use the replyTo parameter of the Messenger to receive messages to the respective Handler.
i have following function run on start and work perfectly.
i would like to add if condition in other function in order to check if device is still connected.
here is code
private final Handler mHandler = new Handler() {
#Override
public void handleMessage(Message msg) {
switch (msg.what) {
case BluetoothService.MESSAGE_STATE_CHANGE:
switch (msg.arg1) {
case BluetoothService.STATE_CONNECTED:
Toast.makeText(getApplicationContext(), "Connect successful",
Toast.LENGTH_SHORT).show();
btnClose.setEnabled(true);
btnSend.setEnabled(true);
btnSendDraw.setEnabled(true);
break;
case BluetoothService.STATE_CONNECTING:
Log.d("À¶ÑÀµ÷ÊÔ","ÕýÔÚÁ¬½Ó.....");
break;
case BluetoothService.STATE_LISTEN:
case BluetoothService.STATE_NONE:
Log.d("À¶ÑÀµ÷ÊÔ","µÈ´ýÁ¬½Ó.....");
break;
}
break;
case BluetoothService.MESSAGE_CONNECTION_LOST:
Toast.makeText(getApplicationContext(), "Device connection was lost",
Toast.LENGTH_SHORT).show();
btnClose.setEnabled(false);
btnSend.setEnabled(false);
btnSendDraw.setEnabled(false);
break;
case BluetoothService.MESSAGE_UNABLE_CONNECT:
Toast.makeText(getApplicationContext(), "Unable to connect device",
Toast.LENGTH_SHORT).show();
break;
}
}
};
other function is start like this
#Override
protected void onPostExecute(String result){
please help me!!
Thanks
ACL_CONNECTED/DISCONNECTED is not exactly reliable, I have learned by experience, because this might happen several times during a device's connection (example, if pin is required, you will get "connected", and then "disconnected" if timeout/wrong pin supplied. This does not necessarily indicate connection proper). This indicates the lower layer connection.
If you want to use a broadcast receiver, it would be better to use the broadcast that is specific to the profile that you have used (example A2DP). Each has it's own broadcast. Another thing you can listen to is Connectivity_state_changed from ConnectivityManager, for the type BLUETOOTH (haven't really tried this one).
Also, the way to check if it is connected, without a broadcast receiver, say, when you want to check in the background before updating an activity, would be to obtain the profile object, via something like:
mBluetoothAdapter.getProfileProxy(mContext, mA2DPProfileListener, BluetoothProfile.A2DP);
where mA2DPProfileListener is a ServiceListener object:
<code>
private ServiceListener mA2DPProfileListener = new ServiceListener(){
//anonymous inner type. etc.
public void onServiceConnected(int profile, BluetoothProfile proxy) {
//cast the BluetoothProfile object to the profile you need, say
//BluetoothA2DP proxyA2DP = (BluetoothA2DP) proxy;
int currentState = proxyA2DP.getConnectionState(mDevice);
//mDevice is the BluetoothDevice object you can get from
//BluetoothAdapter.getRemote...
}
public void onServiceDisconnected(int profile) {
}
}
</code>
you can check what currentState points to, and determine if the device is connected/disconnected/connecting, etc.
HTH,
Sreedevi.
This question already has answers here:
How can I update information in an Android Activity from a background Service
(5 answers)
Closed 9 years ago.
I have an app that receives gcm push notifications. I also have a check in place that if the app is currently open, it does not create the notification. In Android, is it possible in my push service to tell the current activity (IF Available/connected), that a new notification has arrived, refresh your list with the new content? If this is possible, I believe I am on the right path with using IBinders on my service. The thing about that is I am confused on how the Service Calls the Activity (I understand vice verse). Thanks in advance if anyone could help!
Just to be clear. I am trying to tell the activity about a new push message.
Service
public class LocalBinder extends Binder {
GcmIntentService getService() {
return GcmIntentService.this;
}
}
#Override
public IBinder onBind(Intent intent) {
return mBinder;
}
private final IBinder mBinder = new LocalBinder();
Client (Activity)
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 service object we can use to
// interact with the service. Because we have bound to a explicit
// service that we know is running in our own process, we can
// cast its IBinder to a concrete class and directly access it.
mBoundService = ((GcmIntentService.LocalBinder)service).getService();
// Tell the user about this for our demo.
Toast.makeText(MainActivity.this, "Connected", Toast.LENGTH_SHORT).show();
}
public void onServiceDisconnected(ComponentName className) {
// This is called when the connection with the service has been
// unexpectedly disconnected -- that is, its process crashed.
// Because it is running in our same process, we should never
// see this happen.
mBoundService = null;
Toast.makeText(MainActivity.this, "Disconnected",
Toast.LENGTH_SHORT).show();
}
};
void doBindService() {
// Establish a connection with the service. We use an explicit
// class name because we want a specific service implementation that
// we know will be running in our own process (and thus won't be
// supporting component replacement by other applications).
bindService(new Intent(MainActivity.this,
GcmIntentService.class), mConnection, Context.BIND_AUTO_CREATE);
mIsBound = true;
}
void doUnbindService() {
if (mIsBound) {
// Detach our existing connection.
unbindService(mConnection);
mIsBound = false;
}
}
#Override
protected void onDestroy() {
super.onDestroy();
doUnbindService();
}
Yes it's possible.
In your service class have a variable of type YourActivity
MyActivity myActivity = null;
In your onServiceConnected method set this myActivity variable on the service, obtained through the binder.
mBoundService.myActivity = MyActivity.this; // or something similar
Now your service has a pointer to your activity!!! YEah!!
Inside your activity, create a function, the body of this function should refresh the UI with data.
Finally, when the service detects new data, call:
if (myActivity)
myActivity.refreshMyData();
When unbinding, remember to set the myActivity variable to null, otherwise the previous code will fail.
I'm writing an Android app that communicates with a website. Any time I hit the website, I'm displaying a ProcessDialog so that the user knows something's happening. Most of my website communication is one-way, so I don't usually expect any return data.
There is one point however where I need to get information back, but the results are not being stored when I exit the child thread. In a nutshell, I need to call a thread, let it process the results, and store the results in a couple of fields.
Here's what I've got so far - I have two variables, String[] Account and boolean AccountRetrievalSuccess:
public void GetAccount() {
MyDialog = ProgressDialog.show( MyContext, "Retrieving Account" , "We're retrieving your account information. Please wait...", true);
Thread T = new GetAccountThread();
T.start();
}
public class GetAccountThread extends Thread {
#Override
public void run() {
try {
String resp = GetPage(BaseURL+MainPage+"?P="+PhoneID+"&K="+WebAccessKey+"&A=ACCOUNT");
if (resp.contains("FAILURE|")){
failhandler.sendEmptyMessage(0);
} else {
resp = resp.replace("SUCCESS|", "");
Account = resp.split("\\|");
handler.sendEmptyMessage(0);
}
} catch (Exception e) {
failhandler.sendEmptyMessage(0);
}
};
private Handler handler = new Handler() {
#Override
public void handleMessage(Message msg) {
AccountRetrievalSuccess = true;
MyDialog.dismiss();
}
};
private Handler failhandler = new Handler() {
#Override
public void handleMessage(Message msg) {
AccountRetrievalSuccess = false;
MyDialog.dismiss();
ShowWtf();
}
};
}
Any idea what I'd need to do to be able to store the Account and AccountRetrievalSuccess values so that I can access them from elsewhere in the code?
Looks like a perfect job for AsyncTask!
This class allows you to run a task on a background thread and return the results back to the UI thread whilst reporting progress on the task at hand.
Not expecting a result in a mobile app might be a bad idea by the way, due to nature of mobile network connections you'd never know for sure if your server actually got the thing you sent it (and the server might have failed while processing and your app would never know...)
Do not use threads. You should use executors for that. Implement a Callable<> interface, create an ExecutorService and run it. Have a look to the java.util.concurrent package.
Make those global variables in the containing Activity and then pass them to the handler:
Message m = Message.obtain();
m.obj = Account;
handler.sendMessageDelayed(m, 1);
Then in the handler you can cast m.obj back to the Account type and its nice and available.
Scott.. You should not have more than one handler per activity. Instead switch on what. You can send data (or objects) in messages as in:
Message msg= Message.obtainMessage(0);
Bundle b= new Bundle();
b.putString("stringData",outString);
msg.setData(b);
handler.sendMessage(msg);
You can switch on multiple messages in the handler as in.
public void handleMessage(Message msg){
switch(msg.what){
case BUTTON_ONE_UP_SELECTED:
this.removeMessages(BUTTON_ONE_UP_SELECTED);
buttonLarger01.setImageResource(R.drawable.btn_zoom_up_selected);
break;
case BUTTON_ONE_UP_NORMAL:
this.removeMessages(BUTTON_ONE_UP_NORMAL);
buttonLarger01.setImageResource(R.drawable.btn_zoom_up_normal);
break;
case BUTTON_TWO_UP_SELECTED:
this.removeMessages(BUTTON_TWO_UP_SELECTED);
buttonLarger02.setImageResource(R.drawable.btn_zoom_up_selected);
break;
case BUTTON_TWO_UP_NORMAL:
this.removeMessages(BUTTON_TWO_UP_NORMAL);
buttonLarger02.setImageResource(R.drawable.btn_zoom_up_normal);
break;
case BUTTON_ONE_DOWN_SELECTED:
this.removeMessages(BUTTON_ONE_DOWN_SELECTED);
buttonSmaller01.setImageResource(R.drawable.btn_zoom_down_selected);
break;
case BUTTON_ONE_DOWN_NORMAL:
this.removeMessages(BUTTON_ONE_DOWN_NORMAL);
buttonSmaller01.setImageResource(R.drawable.btn_zoom_down_normal);
break;
case BUTTON_TWO_DOWN_SELECTED:
this.removeMessages(BUTTON_TWO_DOWN_SELECTED);
buttonSmaller02.setImageResource(R.drawable.btn_zoom_down_selected);
break;
case BUTTON_TWO_DOWN_NORMAL:
this.removeMessages(BUTTON_TWO_DOWN_NORMAL);
buttonSmaller02.setImageResource(R.drawable.btn_zoom_down_normal);
break;
default:
super.handleMessage(msg);
break;
}
}
};
So in your case you could define SUCCESS as what 0 and FAILURE as what 1 etc.