Android—RecyclerView实现横向滑动翻页（结合圆点指示器功能）

最近项目需求要实现RecyclerView的分页滑动 先上效果图如下(视频压缩成的gif所以滑动切换效果有点卡顿了 效果为每页三条数据的滑动)

效果图

 

一：创建横向布局管理器

/**
 * Created by Sunny on 2019/4/1.
 */
public class HorizontalPageLayoutManager extends RecyclerView.LayoutManager implements PageDecorationLastJudge {
    @Override
    public RecyclerView.LayoutParams generateDefaultLayoutParams() {
        return null;
    }

    int totalHeight = 0;
    int totalWidth = 0;
    int offsetY = 0;
    int offsetX = 0;

    public HorizontalPageLayoutManager(int rows, int columns) {
        this.rows = rows;
        this.columns = columns;
        this.onePageSize = rows * columns;
    }

    @Override
    public boolean canScrollHorizontally() {
        return true;
    }


    @Override
    public int scrollHorizontallyBy(int dx, RecyclerView.Recycler recycler, RecyclerView.State state) {
        detachAndScrapAttachedViews(recycler);
        int newX = offsetX + dx;
        int result = dx;
        if (newX > totalWidth) {
            result = totalWidth - offsetX;
        } else if (newX < 0) {
            result = 0 - offsetX;
        }
        offsetX += result;
        offsetChildrenHorizontal(-result);
        recycleAndFillItems(recycler, state);
        return result;
    }

    private SparseArray<Rect> allItemFrames = new SparseArray<>();

    private int getUsableWidth() {
        return getWidth() - getPaddingLeft() - getPaddingRight();
    }

    private int getUsableHeight() {
        return getHeight() - getPaddingTop() - getPaddingBottom();
    }

    int rows = 0;
    int columns = 0;
    int pageSize = 0;
    int itemWidth = 0;
    int itemHeight = 0;
    int onePageSize = 0;
    int itemWidthUsed;
    int itemHeightUsed;


    @Override
    public void onLayoutChildren(RecyclerView.Recycler recycler, RecyclerView.State state) {

        if (getItemCount() == 0) {
            removeAndRecycleAllViews(recycler);
            return;
        }
        if (state.isPreLayout()) {
            return;
        }
        //获取每个Item的平均宽高
        itemWidth = getUsableWidth() / columns;
        itemHeight = getUsableHeight() / rows;

        //计算宽高已经使用的量，主要用于后期测量
        itemWidthUsed = (columns - 1) * itemWidth;
        itemHeightUsed = (rows - 1) * itemHeight;

        //计算总的页数

//        pageSize = state.getItemCount() / onePageSize + (state.getItemCount() % onePageSize == 0 ? 0 : 1);
        computePageSize(state);
        Log.i("zzz", "itemCount=" + getItemCount() + " state itemCount=" + state.getItemCount() + " pageSize=" + pageSize);
        //计算可以横向滚动的最大值
        totalWidth = (pageSize - 1) * getWidth();

        //分离view
        detachAndScrapAttachedViews(recycler);

        int count = getItemCount();
        for (int p = 0; p < pageSize; p++) {
            for (int r = 0; r < rows; r++) {
                for (int c = 0; c < columns; c++) {
                    int index = p * onePageSize + r * columns + c;
                    if (index == count) {
                        //跳出多重循环
                        c = columns;
                        r = rows;
                        p = pageSize;
                        break;
                    }

                    View view = recycler.getViewForPosition(index);
                    addView(view);
                    //测量item
                    measureChildWithMargins(view, itemWidthUsed, itemHeightUsed);

                    int width = getDecoratedMeasuredWidth(view);
                    int height = getDecoratedMeasuredHeight(view);
                    //记录显示范围
                    Rect rect = all