Android隐藏状态栏和导航栏

public class BaseActivity extends AppCompatActivity {
    @Override
    public void onWindowFocusChanged(boolean hasFocus) {
        super.onWindowFocusChanged(hasFocus);
        if (hasFocus && Build.VERSION.SDK_INT >= 21) {
            View decorView = getWindow().getDecorView();
            decorView.setSystemUiVisibility(
                    View.SYSTEM_UI_FLAG_LAYOUT_STABLE
                            | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
                            | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
                            | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
                            | View.SYSTEM_UI_FLAG_FULLSCREEN
                            | View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY);
            getWindow().setStatusBarColor(Color.TRANSPARENT);
            getWindow().setNavigationBarColor(Color.TRANSPARENT);
        }
    }
}

public class MainActivity extends BaseActivity {

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

    private void hideNavigationBarStatusBar(){
        if (android.os.Build.VERSION.SDK_INT >= 19) {
            Window window;
            window = getWindow();
            WindowManager.LayoutParams params = window.getAttributes();
            params.systemUiVisibility = View.SYSTEM_UI_FLAG_HIDE_NAVIGATION |
                                        View.SYSTEM_UI_FLAG_IMMERSIVE |
                                        View.SYSTEM_UI_FLAG_FULLSCREEN;
            window.setAttributes(params);
            int uiFlags = View.SYSTEM_UI_FLAG_LAYOUT_STABLE
                    | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
                    | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
                    | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION // hide nav bar
                    | View.SYSTEM_UI_FLAG_FULLSCREEN; // hide status bar
            uiFlags |= 0x00001000;    //SYSTEM_UI_FLAG_IMMERSIVE_STICKY: hide navigation bars - compatibility: building API level is lower thatn 19, use magic number directly for higher API target level
            getWindow().getDecorView().setSystemUiVisibility(uiFlags);
        }
    }
}