RecyclerView加载更多数据的三种不同的实现方式

来源：互联网发布：淘宝客户分析编辑：程序博客网时间：2024/06/04 20:04

上拉加载更多数据通过监听RecyclerView的滚动事件RecyclerView.OnScrollListener()实现的，它提供了两个方法：

        /**         * 当RecyclerView的滑动状态改变时触发         */        public void onScrollStateChanged(RecyclerView recyclerView, int newState){}        /**         * 当RecyclerView滑动时触发         * 类似点击事件的MotionEvent.ACTION_MOVE         */        public void onScrolled(RecyclerView recyclerView, int dx, int dy){}

RecyclerView的滑动状态有如下三种：

    /**     * The RecyclerView is not currently scrolling.     * 手指离开屏幕     */    public static final int SCROLL_STATE_IDLE = 0;    /**     * The RecyclerView is currently being dragged by outside input such as user touch input.     * 手指触摸屏幕     */    public static final int SCROLL_STATE_DRAGGING = 1;    /**     * The RecyclerView is currently animating to a final position while not under     * outside control.     * 手指加速滑动并放开，此时滑动状态伴随SCROLL_STATE_IDLE     */    public static final int SCROLL_STATE_SETTLING = 2;

第一种实现：滑动到最后一个item时自动触发的
与手指是否在屏幕上无关，即与滑动状态无关。因此，实现这种效果只需要在public void onScrolled(RecyclerView recyclerView, int dx, int dy) 方法中操作，无需关注当时的滑动状态：

  @Override            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {                super.onScrolled(recyclerView, dx, dy);                Log.d("test", "onScrolled");                int lastVisibleItemPosition = layoutManager.findLastVisibleItemPosition();                if (lastVisibleItemPosition + 1 == adapter.getItemCount()) {                    Log.d("test", "loading executed");                    boolean isRefreshing = swipeRefreshLayout.isRefreshing();                    if (isRefreshing) {                        adapter.notifyItemRemoved(adapter.getItemCount());                        return;                    }                    if (!isLoading) {                        isLoading = true;                        handler.postDelayed(new Runnable() {                            @Override                            public void run() {                                getData();                                Log.d("test", "load more completed");                                isLoading = false;                            }                        }, 1000);                    }                }            }

第二种实现：当且仅当滑动到最后一项并且手指上拉时才执行上拉加载更多
需要配合onScrollStateChanged(RecyclerView recyclerView, int newState的使用，可以将代码改为：

 @Override            public void onScrollStateChanged(RecyclerView recyclerView, int newState) {                super.onScrollStateChanged(recyclerView, newState);                Log.d("test", "StateChanged = " + newState);                if (newState == RecyclerView.SCROLL_STATE_IDLE && lastVisibleItemPosition + 1 == adapter.getItemCount()) {                    Log.d("test", "loading executed");                    boolean isRefreshing = swipeRefreshLayout.isRefreshing();                    if (isRefreshing) {                        adapter.notifyItemRemoved(adapter.getItemCount());                        return;                    }                    if (!isLoading) {                        isLoading = true;                        handler.postDelayed(new Runnable() {                            @Override                            public void run() {                                getData();                                Log.d("test", "load more completed");                                isLoading = false;                            }                        }, 1000);                    }                }            }            @Override            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {                super.onScrolled(recyclerView, dx, dy);                Log.d("test", "onScrolled");                lastVisibleItemPosition = layoutManager.findLastVisibleItemPosition();            }

第三种是：每次滚动到最后一项都触发的加载更多：

  @Override            public void onScrollStateChanged(RecyclerView recyclerView, int newState) {                super.onScrollStateChanged(recyclerView, newState);                int lastVisibleItemPosition = layoutManager.findLastVisibleItemPosition();                if (lastVisibleItemPosition + 1 == adapter.getItemCount()) {                    Log.d("test", "loading executed");                    boolean isRefreshing = swipeRefreshLayout.isRefreshing();                    if (isRefreshing) {                        adapter.notifyItemRemoved(adapter.getItemCount());                        return;                    }                    if (!isLoading) {                        isLoading = true;                        handler.postDelayed(new Runnable() {                            @Override                            public void run() {                                getData();                                Log.d("test", "load more completed");                                isLoading = false;                            }                        }, 1000);                    }                }            }

参考：使用SwipeRefreshLayout和RecyclerView实现仿“简书”下拉刷新和上拉加载更多

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