/**
     * 隐藏底部虚拟按键，且全屏
     */
    private void hideBottomMenu() {
        //隐藏虚拟按键，并且全屏
        if (Build.VERSION.SDK_INT > 11 && Build.VERSION.SDK_INT < 19) { // lower api
            View v = this.getWindow().getDecorView();
            v.setSystemUiVisibility(View.GONE);
        } else if (Build.VERSION.SDK_INT >= 19) {
            //for new api versions.
            View decorView = getWindow().getDecorView();
            int uiOptions = View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
                    | View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY | View.SYSTEM_UI_FLAG_FULLSCREEN;
            decorView.setSystemUiVisibility(uiOptions);
        }
    }