RecyclerView加载更多数据的三种不同的实现方式

最新推荐文章于 2025-06-09 11:34:18 发布

afunyusong

最新推荐文章于 2025-06-09 11:34:18 发布

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本文详细介绍了如何使用SwipeRefreshLayout和RecyclerView在Android应用中实现上拉加载更多数据的功能。通过监听RecyclerView的滚动事件，文章阐述了三种不同的实现方式，包括滑动到最后一个item时自动触发的加载、当且仅当滑动到最后一项并且手指上拉时执行加载、以及每次滚动到最后一项都触发加载的实现方法。

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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);
                    }
                }
            }