沉浸式

注意模拟器版本在4.4.4以上可以看到效果，写在MainActivity里

 @Override    public void onWindowFocusChanged(boolean hasFocus) {        super.onWindowFocusChanged(hasFocus);        if (hasFocus && Build.VERSION.SDK_INT >= 19) {            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);        }    }