Activity中关键代码

public class Activity extends AppCompatActivity{
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        initSysUI();
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_base);
    }


    private void initSysUI() {
        hideSysUI();
        setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
        View decorView = getWindow().getDecorView();
        //监听系统ui可见性变化
        decorView.setOnSystemUiVisibilityChangeListener
                (new View.OnSystemUiVisibilityChangeListener() {
                    @Override
                    public void onSystemUiVisibilityChange(int visibility) {
                        // Note that system bars will only be "visible" if none of the
                        // LOW_PROFILE, HIDE_NAVIGATION, or FULLSCREEN flags are set.
                        if ((visibility & View.SYSTEM_UI_FLAG_FULLSCREEN) == 0) {
                            // TODO: The system bars are visible. Make any desired
                            // adjustments to your UI, such as showing the action bar or
                            // other navigational controls.
                            hideSysUI();
                        } else {
                            // TODO: The system bars are NOT visible. Make any desired
                            // adjustments to your UI, such as hiding the action bar or
                            // other navigational controls.
                        }
                    }
                });
    }

    private void hideSysUI() {
        if (Build.VERSION.SDK_INT < 16) {
            getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                    WindowManager.LayoutParams.FLAG_FULLSCREEN);
        }else {
            View decorView = getWindow().getDecorView();
            int uiOptions = View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
                    | View.SYSTEM_UI_FLAG_IMMERSIVE
                    | View.SYSTEM_UI_FLAG_FULLSCREEN
                    | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
                    | View.SYSTEM_UI_FLAG_LAYOUT_STABLE
                    | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION;
            decorView.setSystemUiVisibility(uiOptions);
            ActionBar actionBar = getActionBar();
            if (null!=actionBar) {
                actionBar.hide();
            }
        }
    }

    @Override
    public void onWindowFocusChanged(boolean hasFocus) {
        super.onWindowFocusChanged(hasFocus);
        if (hasFocus) {
            hideSysUI();
        }
    }
}