Service 사용법

* MainActivity.java

public class MainActivity extends AppCompatActivity {

    EditText editText;

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

        editText = findViewById(R.id.editText);

        Button button = findViewById(R.id.button);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String name = editText.getText().toString();

                Intent intent = new Intent(getApplicationContext(), MyService.class);
                intent.putExtra("command", "show");
                intent.putExtra("name", name);
                startService(intent);
            }
        });

        Intent intent = getIntent();
        processIntent(intent);
    }

    @Override
    protected void onNewIntent(Intent intent) {
        super.onNewIntent(intent);

        processIntent(intent);
    }

    public void processIntent(Intent intent) {
        if (intent != null) {
            String command = intent.getStringExtra("command");
            String name = intent.getStringExtra("name");

            if (command != null && name != null) {
                Toast.makeText(this, "command : " + command + ", name = " + name, Toast.LENGTH_SHORT).show();
            }
        }
    }

}

* MyService.java : New > Service > Service 추가(AndroidManifest.xml에 Service 등록됨)

public class MyService extends Service {

    private static final String TAG = "MyService";

    public MyService() {
    }

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

        Log.d(TAG, "onCreate 호출됨");
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        Log.d(TAG, "onStartCommand 호출됨");

        if (intent != null) {
            processCommand(intent);
        } else {
            return Service.START_STICKY; // 자동 재시작
        }

        return super.onStartCommand(intent, flags, startId);
    }

    public void processCommand(Intent intent) {
        String command = intent.getStringExtra("command");
        String name = intent.getStringExtra("name");

        Log.d(TAG, "command : " + command + ", name : " + name);

        try {
            Thread.sleep(5000);
        } catch (Exception e) {
            e.printStackTrace();
        }

        Intent showIntent = new Intent(getApplicationContext(), MainActivity.class);
        showIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK|
                Intent.FLAG_ACTIVITY_SINGLE_TOP|
                Intent.FLAG_ACTIVITY_CLEAR_TOP);
        showIntent.putExtra("command", "show");
        showIntent.putExtra("name", name + " from service");
        startActivity(showIntent);
    }

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

        Log.d(TAG, "onDestory 호출됨");
    }

    @Override
    public IBinder onBind(Intent intent) {
        // TODO: Return the communication channel to the service.
        throw new UnsupportedOperationException("Not yet implemented");
    }

}