public class MainActivity extends AppCompatActivity {

    private static final String TAG = "MainActivity";

    ImageView mImage;

    View mDecorView;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.main_layout);

        //ButterKnife.bind(this);

        mDecorView = getWindow().getDecorView();

        // 让图片铺满屏幕

        mDecorView.setSystemUiVisibility(

                View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN

                        | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION);

        hideSystemUI();

    }

    private void hideSystemUI() {

        mDecorView.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);

    }

    private void showSystemUI() {

        mDecorView.setSystemUiVisibility(

                View.SYSTEM_UI_FLAG_LAYOUT_STABLE

                        | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION

                        | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN);

    }

    public void click(View v) {

        // 只需要处理隐藏 SystemBar 就行了，因为显示 SystemBar 是由系统完成的

        hideSystemUI();

    }

}