RecyclerView实现横向滑动翻页

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 = allItemFrames.get(index);
                    if (rect == null) {
                        rect = new Rect();
                    }
                    int x = p * getUsableWidth() + c * itemWidth;
                    int y = r * itemHeight;
                    rect.set(x, y, width + x, height + y);
                    allItemFrames.put(index, rect);


                }
            }
            //每一页循环以后就回收一页的View用于下一页的使用
            removeAndRecycleAllViews(recycler);
        }

        recycleAndFillItems(recycler, state);
    }

    private void computePageSize(RecyclerView.State state) {
        pageSize = state.getItemCount() / onePageSize + (state.getItemCount() % onePageSize == 0 ? 0 : 1);
    }

    @Override
    public void onDetachedFromWindow(RecyclerView view, RecyclerView.Recycler recycler) {
        super.onDetachedFromWindow(view, recycler);
        offsetX = 0;
        offsetY = 0;
    }

    private void recycleAndFillItems(RecyclerView.Recycler recycler, RecyclerView.State state) {
        if (state.isPreLayout()) {
            return;
        }

        Rect displayRect = new Rect(getPaddingLeft() + offsetX, getPaddingTop(), getWidth() - getPaddingLeft() - getPaddingRight() + offsetX, getHeight() - getPaddingTop() - getPaddingBottom());
        Rect childRect = new Rect();
        for (int i = 0; i < getChildCount(); i++) {
            View child = getChildAt(i);
            childRect.left = getDecoratedLeft(child);
            childRect.top = getDecoratedTop(child);
            childRect.right = getDecoratedRight(child);
            childRect.bottom = getDecoratedBottom(child);
            if (!Rect.intersects(displayRect, childRect)) {
                removeAndRecycleView(child, recycler);
            }
        }

        for (int i = 0; i < getItemCount(); i++) {
            if (Rect.intersects(displayRect, allItemFrames.get(i))) {
                View view = recycler.getViewForPosition(i);
                addView(view);
                measureChildWithMargins(view, itemWidthUsed, itemHeightUsed);
                Rect rect = allItemFrames.get(i);
                layoutDecorated(view, rect.left - offsetX, rect.top, rect.right - offsetX, rect.bottom);
            }
        }

    }


    @Override
    public boolean isLastRow(int index) {
        if (index >= 0 && index < getItemCount()) {
            int indexOfPage = index % onePageSize;
            indexOfPage++;
            if (indexOfPage > (rows - 1) * columns && indexOfPage <= onePageSize) {
                return true;
            }
        }

        return false;
    }

    @Override
    public boolean isLastColumn(int position) {
        if (position >= 0 && position < getItemCount()) {
            position++;
            if (position % columns == 0) {
                return true;
            }
        }
        return false;
    }

    @Override
    public boolean isPageLast(int position) {
        position++;
        return position % onePageSize == 0;
    }

    @Override
    public int computeHorizontalScrollRange(RecyclerView.State state) {
        computePageSize(state);
        return pageSize * getWidth();
    }

    @Override
    public int computeHorizontalScrollOffset(RecyclerView.State state) {
        return offsetX;
    }

    @Override
    public int computeHorizontalScrollExtent(RecyclerView.State state) {
        return getWidth();
    }
}

二：实现RecyclerView横向滚动工具类

/**
 * 实现RecycleView分页滚动的工具类
 * Created by Sunny on 2019/4/1.
 */

public class PagingScrollHelper {

    RecyclerView mRecyclerView = null;

    private MyOnScrollListener mOnScrollListener = new MyOnScrollListener();

    private MyOnFlingListener mOnFlingListener = new MyOnFlingListener();
    private int offsetY = 0;
    private int offsetX = 0;

    int startY = 0;
    int startX = 0;


    enum ORIENTATION {
        HORIZONTAL, VERTICAL, NULL
    }

    private ORIENTATION mOrientation = ORIENTATION.HORIZONTAL;

    public void setUpRecycleView(RecyclerView recycleView) {
        if (recycleView == null) {
            throw new IllegalArgumentException("recycleView must be not null");
        }
        mRecyclerView = recycleView;
        //处理滑动
        recycleView.setOnFlingListener(mOnFlingListener);
        //设置滚动监听，记录滚动的状态，和总的偏移量
        recycleView.setOnScrollListener(mOnScrollListener);
        //记录滚动开始的位置
        recycleView.setOnTouchListener(mOnTouchListener);
        //获取滚动的方向
        updateLayoutManger();

    }

    public void updateLayoutManger() {
        RecyclerView.LayoutManager layoutManager = mRecyclerView.getLayoutManager();
        if (layoutManager != null) {
            if (layoutManager.canScrollVertically()) {
                mOrientation = ORIENTATION.VERTICAL;
            } else if (layoutManager.canScrollHorizontally()) {
                mOrientation = ORIENTATION.HORIZONTAL;
            } else {
                mOrientation = ORIENTATION.NULL;
            }
            if (mAnimator != null) {
                mAnimator.cancel();
            }
            startX = 0;
            startY = 0;
            offsetX = 0;
            offsetY = 0;

        }

    }

    /**
     * 获取总共的页数
     */
    public int getPageCount() {
        if (mRecyclerView != null) {
            if (mOrientation == ORIENTATION.NULL) {
                return 0;
            }
            if (mOrientation == ORIENTATION.VERTICAL && mRecyclerView.computeVerticalScrollExtent() != 0) {
                return mRecyclerView.computeVerticalScrollRange() / mRecyclerView.computeVerticalScrollExtent();
            } else if (mRecyclerView.computeHorizontalScrollExtent() != 0) {
                Log.i("zzz","rang="+mRecyclerView.computeHorizontalScrollRange()+" extent="+mRecyclerView.computeHorizontalScrollExtent());
                return mRecyclerView.computeHorizontalScrollRange() / mRecyclerView.computeHorizontalScrollExtent();
            }
        }
        return 0;
    }



    ValueAnimator mAnimator = null;

    public void scrollToPosition(int position) {
        if (mAnimator == null) {
            mOnFlingListener.onFling(0, 0);
        }
        if (mAnimator != null) {
            int startPoint = mOrientation == ORIENTATION.VERTICAL ? offsetY : offsetX, endPoint = 0;
            if (mOrientation == ORIENTATION.VERTICAL) {
                endPoint = mRecyclerView.getHeight() * position;
            } else {
                endPoint = mRecyclerView.getWidth() * position;
            }
            if (startPoint != endPoint) {
                mAnimator.setIntValues(startPoint, endPoint);
                mAnimator.start();
            }
        }
    }

    public class MyOnFlingListener extends RecyclerView.OnFlingListener {

        @Override
        public boolean onFling(int velocityX, int velocityY) {
            if (mOrientation == ORIENTATION.NULL) {
                return false;
            }
            //获取开始滚动时所在页面的index
            int p = getStartPageIndex();

            //记录滚动开始和结束的位置
            int endPoint = 0;
            int startPoint = 0;

            //如果是垂直方向
            if (mOrientation == ORIENTATION.VERTICAL) {
                startPoint = offsetY;

                if (velocityY < 0) {
                    p--;
                } else if (velocityY > 0) {
                    p++;
                }
                //更具不同的速度判断需要滚动的方向
                //注意，此处有一个技巧，就是当速度为0的时候就滚动会开始的页面，即实现页面复位
                endPoint = p * mRecyclerView.getHeight();

            } else {
                startPoint = offsetX;
                if (velocityX < 0) {
                    p--;
                } else if (velocityX > 0) {
                    p++;
                }
                endPoint = p * mRecyclerView.getWidth();

            }
            if (endPoint < 0) {
                endPoint = 0;
            }

            //使用动画处理滚动
            if (mAnimator == null) {
                mAnimator = new ValueAnimator().ofInt(startPoint, endPoint);

                mAnimator.setDuration(300);
                mAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
                    @Override
                    public void onAnimationUpdate(ValueAnimator animation) {
                        int nowPoint = (int) animation.getAnimatedValue();

                        if (mOrientation == ORIENTATION.VERTICAL) {
                            int dy = nowPoint - offsetY;
                            //这里通过RecyclerView的scrollBy方法实现滚动。
                            mRecyclerView.scrollBy(0, dy);
                        } else {
                            int dx = nowPoint - offsetX;
                            mRecyclerView.scrollBy(dx, 0);
                        }
                    }
                });
                mAnimator.addListener(new AnimatorListenerAdapter() {
                    @Override
                    public void onAnimationEnd(Animator animation) {
                        //回调监听
                        if (null != mOnPageChangeListener) {
                            mOnPageChangeListener.onPageChange(getPageIndex());
                        }
                        //修复双击item bug
                        mRecyclerView.stopScroll();
                        startY = offsetY;
                        startX = offsetX;
                    }
                });
            } else {
                mAnimator.cancel();
                mAnimator.setIntValues(startPoint, endPoint);
            }

            mAnimator.start();

            return true;
        }
    }

    public class MyOnScrollListener extends RecyclerView.OnScrollListener {
        @Override
        public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
            //newState==0表示滚动停止，此时需要处理回滚
            if (newState == 0 && mOrientation != ORIENTATION.NULL) {
                boolean move;
                int vX = 0, vY = 0;
                if (mOrientation == ORIENTATION.VERTICAL) {
                    int absY = Math.abs(offsetY - startY);
                    //如果滑动的距离超过屏幕的一半表示需要滑动到下一页
                    move = absY > recyclerView.getHeight() / 2;
                    vY = 0;

                    if (move) {
                        vY = offsetY - startY < 0 ? -1000 : 1000;
                    }

                } else {
                    int absX = Math.abs(offsetX - startX);
                    move = absX > recyclerView.getWidth() / 2;
                    if (move) {
                        vX = offsetX - startX < 0 ? -1000 : 1000;
                    }

                }

                mOnFlingListener.onFling(vX, vY);

            }

        }

        @Override
        public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
            //滚动结束记录滚动的偏移量
            offsetY += dy;
            offsetX += dx;
        }
    }

    private MyOnTouchListener mOnTouchListener = new MyOnTouchListener();

    private boolean firstTouch = true;

    public class MyOnTouchListener implements View.OnTouchListener {

        @Override
        public boolean onTouch(View v, MotionEvent event) {
            //手指按下的时候记录开始滚动的坐标
            if (firstTouch) {
                //第一次touch可能是ACTION_MOVE或ACTION_DOWN,所以使用这种方式判断
                firstTouch = false;
                startY = offsetY;
                startX = offsetX;
            }
            if (event.getAction() == MotionEvent.ACTION_UP || event.getAction() == MotionEvent.ACTION_CANCEL) {
                firstTouch = true;
            }

            return false;
        }

    }

    private int getPageIndex() {
        int p = 0;
        if (mRecyclerView.getHeight() == 0 || mRecyclerView.getWidth() == 0) {
            return p;
        }
        if (mOrientation == ORIENTATION.VERTICAL) {
            p = offsetY / mRecyclerView.getHeight();
        } else {
            p = offsetX / mRecyclerView.getWidth();
        }
        return p;
    }

    private int getStartPageIndex() {
        int p = 0;
        if (mRecyclerView.getHeight() == 0 || mRecyclerView.getWidth() == 0) {
            //没有宽高无法处理
            return p;
        }
        if (mOrientation == ORIENTATION.VERTICAL) {
            p = startY / mRecyclerView.getHeight();
        } else {
            p = startX / mRecyclerView.getWidth();
        }
        return p;
    }

    onPageChangeListener mOnPageChangeListener;

    public void setOnPageChangeListener(onPageChangeListener listener) {
        mOnPageChangeListener = listener;
    }

    public interface onPageChangeListener {
        void onPageChange(int index);
    }

}

三：初始化RecyclerView同时设置为横向滑动
 

//使用通用RecyclerView组件   
 PagingScrollHelper scrollHelper = new PagingScrollHelper();//初始化横向管理器
        HorizontalPageLayoutManager horizontalPageLayoutManager = new HorizontalPageLayoutManager(1, 3);//这里两个参数是行列，这里实现的是一行三列
        titleAdapter = new RsdTitleAdapter(this);//设置适配器
        mrecRsd.setAdapter(titleAdapter);
        scrollHelper.setUpRecycleView(mrecRsd);//将横向布局管理器和recycler view绑定到一起
        scrollHelper.setOnPageChangeListener(this);//设置滑动监听
        mrecRsd.setLayoutManager(horizontalPageLayoutManager);//设置为横向
        scrollHelper.updateLayoutManger();
        scrollHelper.scrollToPosition(0);//默认滑动到第一页
        mrecRsd.setHorizontalScrollBarEnabled(true);

四：页面滑动监听
 

//页面切换
    @Override
    public void onPageChange(int index) {
        //这里是配合圆点指示器实现的，可以忽略
        for (int i = 0; i < dotViews.length; i++) {
            if (index == i) {
                dotViews[i].setSelected(true);
                dotViews[i].setImageResource(R.drawable.red_circle);
            } else {
                dotViews[i].setSelected(false);
                dotViews[i].setImageResource(R.drawable.gry_circle);
            }
        }
    }