在后台运行Intent服务

Question

I am trying to run intent service in background even if the app is closed and have written this code. But the service doesn't runs in the background.Here is my code.

MainActivity.java

package com.example.h.intentservice;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    public void startService(View view){
        Intent intent = new Intent(this,MyIntentService.class);
        startService(intent);

    }

    public void stopService(View view){
      Intent intent=new Intent(this,MyIntentService.class);
        stopService(intent);
    }
}

MyIntentService.java

public class MyIntentService extends IntentService {

    public MyIntentService() {
        super("My_Worker_Thread");
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        Toast.makeText(this,"Service started",Toast.LENGTH_LONG).show();
        return super.onStartCommand(intent, flags, startId);
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        Toast.makeText(this,"Stopped",Toast.LENGTH_LONG).show();
    }

    @Override
    protected void onHandleIntent(Intent intent) {

        synchronized (this){
            int count=0;
            while(count<=10)
            {
                try{
                    wait(1500);
                    count++;
                }
                catch (InterruptedException e){
                    e.printStackTrace();
                }
            }
        }
    }
}   

Answer 1

First of all an intent service cannot run in the background after closing the application. An intentService is run only once and it automatically closes the thread once the task assigned to it is done. You will have to use a service for background requests. Secondly you have not called the startService() method from the onCreate and therefore the serviceIntent has not been initiated. In both the startService() method and the stopService() method you are passing a view which i can see is unused inside the method body. So therefore i can advice you to adjust your code this way

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    startService();

    //here you have started the service intent
    //if you want to stop the same just call stopService()
}

public void startService(){
    Intent intent = new Intent(this,MyIntentService.class);
    startService(intent);

}

public void stopService(){
  Intent intent=new Intent(this,MyIntentService.class);
    stopService(intent);
}

Am also posting sample code for a service that can run in the background.

Below is sample code for a service

public class UploadService extends Service {

 public int counter = 0;

    public UploadService(Context applicationContext) {
        super();

        Log.i("SERVICE", "hService started");
    }

    public UploadService() {
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        super.onStartCommand(intent, flags, startId);

        //instantiate your variables here

        //i call my startUpload method here to doing the task assigned to it

        startUpload();

        return START_STICKY;
    }



    public void startUpload() {

    //call the method with your logic here

    //mine is a sample to print a log after every x seconds

        initializeTimerTask();

    }

    /**
     * it sets the timer to print the counter every x seconds
     */
    public void initializeTimerTask() {
        // timerTask = new TimerTask() {

        //we can print it on the logs as below
        Log.i("in timer", "in timer ++++  " + (counter++));

        //or use the print statement as below
        System.out.println("Timer print " + counter++);

    }

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }


      @Override
    public void onDestroy() {
        super.onDestroy();
        stopSelf();
    }

}