android实现上滑屏幕隐藏底部菜单栏的示例

public class BottomNavigationBehavior extends CoordinatorLayout.Behavior {
 private ObjectAnimator outAnimator, inAnimator;
 public BottomNavigationBehavior(Context context, AttributeSet attrs) {
 super(context, attrs);
 }

 // 垂直滑动
 @Override
 public boolean onStartNestedScroll(CoordinatorLayout coordinatorLayout, View child, View directTargetChild, View target, int nestedScrollAxes) {
 return nestedScrollAxes == ViewCompat.SCROLL_AXIS_VERTICAL;
 }

 @Override
 public void onNestedPreScroll(CoordinatorLayout coordinatorLayout, View child, View target, int dx, int dy, int[] consumed) {
 if (dy > 0) {// 上滑隐藏
  if (outAnimator == null) {
  outAnimator = ObjectAnimator.ofFloat(child, "translationY", 0, child.getHeight());
  outAnimator.setDuration(200);
  }
  if (!outAnimator.isRunning() && child.getTranslationY() <= 0) {
  outAnimator.start();
  }
 } else if (dy <0) {// 下滑显示
  if (inAnimator == null) {
  inAnimator = ObjectAnimator.ofFloat(child, "translationY", child.getHeight(), 0);
  inAnimator.setDuration(200);
  }
  if (!inAnimator.isRunning() && child.getTranslationY() >= child.getHeight()) {
  inAnimator.start();
  }
 }
 }
}