从应用程序类执行Activity的AsyncTask

Question

I'm trying to find a way to automate the execution of an AsyncTask, currently it's working from a button press.

To give some context -

Application Class

// The Handler that gets information back from the BluetoothService
public final Handler mHandler = new Handler() {
    @Override
    public void handleMessage(Message msg) {
        switch (msg.what) {                
            case MESSAGE_READ:
                Log.d(TAG, "MESSAGE_READ");
                byte[] readBuf = (byte[]) msg.obj;
                readMessage = new String(readBuf);
                break;
        }
    }
};

Activity - AsyncTask Subclass

private class PostTask extends AsyncTask<Void, Void, Void> {

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        readBuf = ((MyApplication) getApplication()).getReadBuf();
        speedcur1 = speedometer.getCurrentSpeed();
        speedcur2 = speedometer1.getCurrentSpeed();
    }

    @Override
    protected Void doInBackground(Void... params) {
        if (readBuf.startsWith("V")) {
            readBuf = readBuf.replace("V", "");
            String[] parts = readBuf.split(",");
            String part1 = parts[0];
            String part2 = parts[1];
            speed1 = Float.parseFloat(part1);
            speed2 = Float.parseFloat(part2);
            finalspeed1 = ((speed1 * 102) / 100);
            finalspeed2 = ((speed2 * 602) / 100);
        }
        return null;
    }

    @Override
    protected void onProgressUpdate(Void... values) {
        super.onProgressUpdate(values);
    }

    @Override
    protected void onPostExecute(Void result) {
        super.onPostExecute(result);
        speedometer.onSpeedChanged(speedometer.getCurrentSpeed() - speedcur1);
        speedometer.onSpeedChanged(speedometer.getCurrentSpeed() + finalspeed1);
        speedometer1.onSpeedChanged(speedometer1.getCurrentSpeed() - speedcur2);
        speedometer1.onSpeedChanged(speedometer1.getCurrentSpeed() + finalspeed2);
        myLabel.setText(readBuf);
    }
}

I have extended my Application class, inside this class is a handler which reads messages sent from my service, msg.arg1 is read inside this handler and selects the appropriate case.

Inside my message_read case the msg.obj is saved as a byte[], then saved as a String.

My current idea is to somehow execute the AsynTask inside my activity from the application class handler after checking if the activity in question is currently running. Originally I had this functionality working inside a loop however after making huge changes to my app the requirements have changed as a Bluetooth connection service is shared between two activities.

Answer 1

Yes you can run AsyncTask from application class and check according to your logic to run or not?

    public class BaseJuiceApplication extends Application  {

        public static BaseJuiceApplication instance = null;

        public static Context getInstance() {
            if (null == instance) {
                instance = new BaseJuiceApplication();
            }
            return instance;
        }

        @Override
        public void onCreate() {
            super.onCreate();

            if(getPrefs.getBoolean("MyKKey")){
              // any of your logic 
                 new LongOperation().execute("");
                }

        }

    private class LongOperation extends AsyncTask<String, Void, String> {

        @Override
        protected String doInBackground(String... params) {

            return "Executed";
        }

        @Override
        protected void onPostExecute(String result) {
        }

        @Override
        protected void onPreExecute() {}

    }
  }
}

Answer 2

1.create an interface

2.Implement that interface in activity.

3.Then, register that interface from activity into the application class

4.After than do callback from application class

5.Make sure to unregister from activity in onDestroy or onStop

public class ApplicationClass extends Appliation{

    private static ApplicationClass instance;
    private TestInterface mCallBack;

    public final Handler mHandler = new Handler() {
    @Override
    public void handleMessage(Message msg) {
        switch (msg.what) {                
            case MESSAGE_READ:
                if(mCallBack!=null){
                  mCallBack.doSomething();
                }
                break;
        }
    }
};


    public void onCreate(){
       instance = this;
    }


    public ApplicationClass getInstance(){
        return instance;
    }

    public void register(TestInterface callBack){
      mCallBack = callBack;
    }

    public void unRegister(){
      mCallBack = null;
    }



}

public interface TestInterface{

    void doSomething();

}

public class MainActivity extends Activity implements TestInterface{

  @Override 
  public void doSomething(){

  }

  @Override 
  public void onStop(){
   ApplicationClass.getInstance().unRegister();
  }

  @Override
  public void onStart(){
   ApplicationClass.getInstance().register(this);
  }

}