預期效果是大多app都會用到的首頁頂部圖片banner，3s自動輪播，也可手動切換

用法很簡單，做attach就好(以下為kotlin程式碼)

recyclerView.layoutManager = LinearLayoutManager(context, LinearLayoutManager.HORIZONTAL, false)
val snapHelper = PagerSnapHelper()
snapHelper.attachToRecyclerView(recyclerView)

自動翻頁是定義的handler每3s執行一次recyclerView滾動，但是注意滾動的方法要使用

recyclerView.smoothScrollToPosition(bannerPos)

使用的話scrollToPosition()就不會有左右平滑的效果

如果需要同步更新Indicator，在recyclerView的滑動監聽裡

recyclerView.addOnScrollListener(object : RecyclerView.OnScrollListener() {
                    override fun onScrollStateChanged(recycler: RecyclerView, newState: Int) {
                        super.onScrollStateChanged(recycler, newState)
                        when (newState) {
                            RecyclerView.SCROLL_STATE_IDLE 
 
-> {
                                val viewIdle = snapHelper.findSnapView(recyclerView.layoutManager)
                                if (viewIdle != null) {
                                    val pos = recyclerView.layoutManager?.getPosition(viewIdle) ?: 0
                                    updateIndicators(pos)
                                }
                            }
                        }
                    }
                })
　　
 
/**
     * 更新到當前指示器
     */
    private fun updateIndicators(position: Int) {
        for (i in 0 until indicatorContainer.childCount) {
            val childView = indicatorContainer.getChildAt(i)
            childView.background = if (position == i)
               resources.getDrawable(R.drawable.shape_indicator_orange)
            else
               resources.getDrawable(R.drawable.shape_indicator_gray)
        }
    }

補充一下indicator的初始化方法

private fun setIndicators(bannerList: List<String>?) {
        //只有一頁的時候不顯示指示器
        if (bannerList?.size ?: 0 <= 1) {
            return
        }
        indicatorContainer.removeAllViews()
        for (i in bannerList!!.indices) {
            val indicatorView = View(context)
            indicatorView.background = resources.getDrawable(R.drawable.shape_indicator_gray)
            val layoutParams: LinearLayout.LayoutParams = LinearLayout.LayoutParams(
                ConvertUtils.dp2px(6f), ConvertUtils.dp2px(6f)
            )
            if (i != 0) layoutParams.leftMargin = ConvertUtils.dp2px(8f)
            indicatorView.layoutParams = layoutParams
            indicatorContainer.addView(indicatorView)
        }
        updateIndicators(indicatorContainer, 0)
    }