使用FLAG_ACTIVITY_SINGLE_TOP缓慢打开已打开的活动

Question

我正在尝试使用在调用onPause时弹出的浮动窗口小部件，并在单击时重新启动活动，我使用了FLAG_ACTIVITY_SINGLE_TOP，因此它不会启动新活动，但如果已经显示活动则需要花费大量时间打开。

package com.example.myapplication;

public class MainActivity extends AppCompatActivity {

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

    private void askForSystemOverlayPermission() {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M && !Settings.canDrawOverlays(this)) {
            Log.d("mmm", "asking permission");
            Intent intent = new Intent(Settings.ACTION_MANAGE_OVERLAY_PERMISSION,
                    Uri.parse("package:" + getPackageName()));
            startActivityForResult(intent, 1);
        }
    }

    @Override
    protected void onPostResume() {
        super.onPostResume();
        stopService(new Intent(this, MyService.class));
    }

    @Override
    protected void onPause() {
        super.onPause();
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M && Settings.canDrawOverlays(this) || Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
            startService(new Intent(this, MyService.class));
        }
    }
}

    package com.example.myapplication;

public class MyService extends Service {

    private WindowManager manager;
    private ImageView v;

    @SuppressLint("ClickableViewAccessibility")
    @Override
    public void onCreate() {
        super.onCreate();
        v = new ImageView(this);
        v.setImageResource(R.drawable.ic_launcher_background);
        manager = (WindowManager) getSystemService(WINDOW_SERVICE);
        v.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                GoToActivity();
            }
        });
        WindowManager.LayoutParams params = new WindowManager.LayoutParams(
                150, 150,
                WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY,
                WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
                PixelFormat.TRANSLUCENT);


        manager.addView(v, params);

        v.setOnTouchListener(new View.OnTouchListener() {
            float dX;
            float dY;
            int lastAction;

            @Override
            public boolean onTouch(View v, MotionEvent event) {
                WindowManager.LayoutParams layoutParams = (WindowManager.LayoutParams) v.getLayoutParams();
                switch (event.getActionMasked()) {
                    case MotionEvent.ACTION_DOWN:
                        dX = layoutParams.x - event.getRawX();
                        dY = layoutParams.y - event.getRawY();
                        lastAction = MotionEvent.ACTION_DOWN;
                        break;

                    case MotionEvent.ACTION_MOVE:
                        layoutParams.y = (int) (event.getRawY() + dY);
                        layoutParams.x = (int) (event.getRawX() + dX);
                        manager.updateViewLayout(v, layoutParams);
                        lastAction = MotionEvent.ACTION_MOVE;
                        break;

                    case MotionEvent.ACTION_UP:
                        if (lastAction == MotionEvent.ACTION_DOWN)
                            break;

                    default:
                        return false;
                }
                return false;
            }
        });
    }


    private void GoToActivity() {
        Intent i = new Intent(this, MainActivity.class);
        i.setFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);
        stopSelf();
        startActivity(i);
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        manager.removeView(v);
    }

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

Answer 1

不是用MainActivity发布FLAG_ACTIVITY_SINGLE_TOP，为什么不把现有的任务推进？

而不是这个：

    Intent i = new Intent(this, MainActivity.class);
    i.setFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);
    stopSelf();
    startActivity(i);

做这个：

    Intent i = getPackageManager().getLaunchIntentForPackage("may.package.name");
    stopSelf();
    startActivity(i);