自定义ScrollView 实现上拉下拉的回弹效果--并且子控件中有Viewpager的情况

onInterceptTouchEvent就是对子控件中Viewpager的处理：左右滑动应该让viewpager消费

 public class MyScrollView extends ScrollView {

     private View childView;

     public MyScrollView(Context context) {
         super(context);
     }

     public MyScrollView(Context context, AttributeSet attrs) {
         super(context, attrs);
     }

     public MyScrollView(Context context, AttributeSet attrs, int defStyleAttr) {
         super(context, attrs, defStyleAttr);
     }

 //    @Override
 //    protected void onLayout(boolean changed, int l, int t, int r, int b) {
 //        super.onLayout(changed, l, t, r, b);
 //    }

     //获取子视图
     @Override
     protected void onFinishInflate() {
         super.onFinishInflate();
         if (getChildCount() > ) {
             childView = getChildAt();
         }
     }

     private int lastY;//上一次y轴方向操作的坐标位置
     private Rect normal = new Rect();//用于记录临界状态的左、上、右、下
     private boolean isFinishAnimation = true;//是否动画结束

     private int lastX, downX, downY;

     //拦截:实现父视图对子视图的拦截
     //是否拦截成功，取决于方法的返回值。返回值true:拦截成功。反之，拦截失败
     @Override
     public boolean onInterceptTouchEvent(MotionEvent ev) {
         boolean isIntercept = false;
         int eventX = (int) ev.getX();
         int eventY = (int) ev.getY();
         switch (ev.getAction()) {
             case MotionEvent.ACTION_DOWN:
                 lastX = downX = eventX;
                 lastY = downY = eventY;
                 break;
             case MotionEvent.ACTION_MOVE:
                 //获取水平和垂直方向的移动距离
                 int absX = Math.abs(eventX - downX);
                 int absY = Math.abs(eventY - downY);

                 if(absY > absX && absY >= UIUtils.dp2px()){
                     isIntercept = true;//执行拦截
                 }

                 lastX = eventX;
                 lastY = eventY;
                 break;
         }

         return isIntercept;
     }

     @Override
     public boolean onTouchEvent(MotionEvent ev) {
         if (childView == null || !isFinishAnimation) {
             return super.onTouchEvent(ev);
         }

         int eventY = (int) ev.getY();//获取当前的y轴坐标
         switch (ev.getAction()) {
             case MotionEvent.ACTION_DOWN:
                 lastY = eventY;
                 break;
             case MotionEvent.ACTION_MOVE:

                 int dy = eventY - lastY;//微小的移动量

                 if (isNeedMove()) {
                     if (normal.isEmpty()) {
                         //记录了childView的临界状态的左、上、右、下
                         normal.set(childView.getLeft(), childView.getTop(), childView.getRight(), childView.getBottom());

                     }
                     //重新布局
                     childView.layout(childView.getLeft(), childView.getTop() + dy / , childView.getRight(), childView.getBottom() + dy / );
                 }

                 lastY = eventY;//重新赋值
                 break;
             case MotionEvent.ACTION_UP:
                 if (isNeedAnimation()) {
                     //使用平移动画
                     int translateY = childView.getBottom() - normal.bottom;
                     TranslateAnimation translateAnimation = new TranslateAnimation(, , , -translateY);
                     translateAnimation.setDuration();
 //                translateAnimation.setFillAfter(true);//停留在最终位置上

                     translateAnimation.setAnimationListener(new Animation.AnimationListener() {
                         @Override
                         public void onAnimationStart(Animation animation) {
                             isFinishAnimation = false;
                         }

                         @Override
                         public void onAnimationEnd(Animation animation) {
                             isFinishAnimation = true;
                             childView.clearAnimation();//清除动画
                             //重新布局
                             childView.layout(normal.left, normal.top, normal.right, normal.bottom);
                             //清除normal的数据
                             normal.setEmpty();
                         }

                         @Override
                         public void onAnimationRepeat(Animation animation) {

                         }
                     });

                     //启动动画
                     childView.startAnimation(translateAnimation);
                 }

                 break;
         }

         return super.onTouchEvent(ev);
     }

     //判断是否需要执行平移动画
     private boolean isNeedAnimation() {
         return !normal.isEmpty();

     }

     private boolean isNeedMove() {
         int childMeasuredHeight = childView.getMeasuredHeight();//获取子视图的高度
         int scrollViewMeasuredHeight = this.getMeasuredHeight();//获取布局的高度

         Log.e("TAG", "childMeasuredHeight = " + childMeasuredHeight);
         Log.e("TAG", "scrollViewMeasuredHeight = " + scrollViewMeasuredHeight);

         int dy = childMeasuredHeight - scrollViewMeasuredHeight;//dy >= 0

         int scrollY = this.getScrollY();//获取用户在y轴方向上的偏移量 （上 + 下 -）
         if (scrollY <=  || scrollY >= dy) {
             return true;//按照我们自定义的MyScrollView的方式处理
         }
         //其他处在临界范围内的，返回false。即表示，仍按照ScrollView的方式处理
         return false;
     }
 }