@Override
 public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
  View v = mListView.getChildAt(0);
  //当firstItem的top为0的时候就认为已经到达ListView的顶部了
  if (mListView.getChildCount() > 0 && firstVisibleItem == 0) {
   //滑动到顶部
   if (v.getTop() == 0) {
    //滑动到顶部了
    isListViewTop = true;
   } else {
    isListViewBottom = false;
   }
  }else if (mListView.getChildCount()>0&&firstVisibleItem+visibleItemCount==totalItemCount){
   final View bottomChildView = mListView.getChildAt(mListView.getChildCount()-1);
//当最后一个itemView的bottom>=ListView的高度的时候，那么就认为到达底部了
   if    (mListView.getHeight()>=bottomChildView.getBottom()){
    isListViewBottom = true;
   }else {
    isListViewBottom = false;
   }
  }else {
   isListViewBottom = false;
   isListViewTop = false;
  }

 @Override
 public boolean onInterceptTouchEvent(MotionEvent ev) {
  switch (ev.getAction()) {
   case MotionEvent.ACTION_DOWN:
    touchY = ev.getRawY();
    isIntercept = false;
    break;
   case MotionEvent.ACTION_MOVE:
    float distant = ev.getRawY() - touchY;
    if (isListViewTop) {
     switch (mHeadPosition) {
      case TOP:
       if (distant > 0) isIntercept = true;
       break;
      case CENTER:
       isIntercept = true;
       break;
     }
    }
    if (isListViewBottom){
     switch (mHeadPosition) {
      case CENTER:
       isIntercept = true;
       break;
      case BOTTOM:
       if (distant < 0) isIntercept = true;
       break;
     }
    }

    break;
   case MotionEvent.ACTION_UP:
    isIntercept = true;
    break;
  }
  return isIntercept;
 }

public static final int TOP = 0;//收缩状态
public static final int CENTER = 1;//中间状态
public static final int BOTTOM = 2;//展开状态

@Override
public boolean onTouchEvent(MotionEvent event) {
 switch (event.getAction()) {
  case MotionEvent.ACTION_DOWN:
   //获取不到的
   break;
  case MotionEvent.ACTION_MOVE:
   int distant = (int) (touchY - event.getRawY());
   if (getScrollY() + distant-1 < MAXY && getScrollY() + distant > 0) {
    scrollTo(0, getScrollY() + distant);
   }
   break;
  case MotionEvent.ACTION_UP:
   if (getScrollY() == 0) mHeadPosition = BOTTOM;
   if (getScrollY() == MAXY) mHeadPosition = TOP;
   if (getScrollY() > 0 && getScrollY() < MAXY) mHeadPosition = CENTER;
   if (getScrollY() > MAXY / 2) {
    mScroll.startScroll(0, getScrollY(), 0, MAXY-getScrollY(),100);
    invalidate();
    mHeadPosition = TOP;
   }
   if (getScrollY() < MAXY / 2) {
    mScroll.startScroll(0, getScrollY(),0,-getScrollY(),100);
    invalidate();
    mHeadPosition = BOTTOM;
   }
   break;
 }
 return super.onTouchEvent(event);
}

@Override
public void computeScroll() {
 super.computeScroll();
 if (mScroll.computeScrollOffset()){
  scrollTo(mScroll.getCurrX(),mScroll.getCurrY());
  postInvalidate();
 }
}

 if (MAXY == -1)
  MAXY = mHeadSecond.getMeasuredHeight();

 @Override
  protected void onFinishInflate() {
  super.onFinishInflate();
  int count = getChildCount();
  //本粘性布局只支持ListView
  if (count == 3 && getChildAt(2) instanceof ListView)
   init();
 }

 /**
  * 初始化
  */
 private void init() {
  //获得子元素
  mHeadFiest = getChildAt(0);
  mHeadSecond = getChildAt(1);
  mListView = (ListView) getChildAt(2);
  mListView.setOnScrollListener(this);
  mScroll = new Scroller(getContext());
 }