android开发仿ios的UIScrollView实例代码

//视图不为空即可滚动
  protected void onFinishInflate() {
    if (getChildCount() > 0) {
      childview = getChildAt(0);
    }
  }

if (childview != null) {
      int action = event.getAction();
      switch (action) {
        case MotionEvent.ACTION_DOWN:
          break;
        case MotionEvent.ACTION_UP:
          //判断是否需要动画
          if (!normal.isEmpty()) {
            animation();
            isCount = false;
          }
          break;
        case MotionEvent.ACTION_MOVE:
          final float DownY = startY;
          float moveY = event.getY();
          int distance = (int) (DownY - moveY);
          if (!isCount) {
            distance = 0; // 在这里要归0.
          }
          startY = moveY;
          if (isNeedMove()) {
            //顶部
            if (normal.isEmpty()) {
              normal.set(childview.getLeft(), childview.getTop(),
                  childview.getRight(), childview.getBottom());
            }
            //底部
            childview.layout(childview.getLeft(), childview.getTop() - distance / 2,
                childview.getRight(), childview.getBottom() - distance / 2);
          }
          isCount = true;
          break;
      }

 public void animation() {
    // 开启移动动画
    TranslateAnimation animation = new TranslateAnimation(0, 0, childview.getTop(),
        normal.top);
    animation.setDuration(200);
    childview.startAnimation(animation);
    // 设置回到正常的布局位置
    childview.layout(normal.left, normal.top, normal.right, normal.bottom);
    normal.setEmpty();
  }

 public boolean isNeedMove() {
    int offset = childview.getHeight() - getHeight();
    int scrollY = getScrollY();
    // 0是顶部，后面那个是底部
    if (scrollY == 0 || scrollY == offset) {
      return true;
    }
    return false;
  }