如何在Android中实现分页列表视图

Question

我想在 android 中实现分页列表视图，所以当我向下滚动到最后时，每次应该添加更多项目到我的列表中，目前我正在从 Web 服务获取 10 个项目并将它们显示在列表视图中，现在我当用户向下滚动到列表末尾时，想要再添加 10 个项目。 有什么办法吗？

Answer 1

编辑：这个更好：http://p-xr.com/android-tutorial-dynamicaly-load-more-items-to-the-listview-never-ending-list/

-------------------------------- ---*------------------- ---

http://benjii.me/2010/08/endless-scrolling-listview-in-android/

public class EndlessScrollListener implements OnScrollListener {

    private int visibleThreshold = 5;
    private int currentPage = 0;
    private int previousTotal = 0;
    private boolean loading = true;

    public EndlessScrollListener() {
    }
    public EndlessScrollListener(int visibleThreshold) {
        this.visibleThreshold = visibleThreshold;
    }

    @Override
    public void onScroll(AbsListView view, int firstVisibleItem,
            int visibleItemCount, int totalItemCount) {
        if (loading) {
            if (totalItemCount > previousTotal) {
                loading = false;
                previousTotal = totalItemCount;
                currentPage++;
            }
        }
        if (!loading && (totalItemCount - visibleItemCount) <= (firstVisibleItem + visibleThreshold)) {
            // I load the next page of gigs using a background task,
            // but you can call any function here.
            new LoadGigsTask().execute(currentPage + 1);
            loading = true;
        }
    }

    @Override
    public void onScrollStateChanged(AbsListView view, int scrollState) {
    }
}

Answer 2

我在这里找到了一个更好的解决方案，它实际上看起来像是对 Waza_Be 解决方案的增强：https://github.com/thecodepath/android_guides/wiki/Endless-Scrolling-with-AdapterViews（我不是作者，所以归功于https://github.com/thecodepath）。

一个抽象的监听器类是用一个负责加载数据的抽象方法来实现的，这对于活动发送它们的特定请求非常有用。

我只是在这里发布代码，如果代码不知何故在 wiki 中消失了。

public abstract class EndlessScrollListener implements OnScrollListener {
    // The minimum amount of items to have below your current scroll position
    // before loading more.
    private int visibleThreshold = 5;
    // The current offset index of data you have loaded
    private int currentPage = 0;
    // The total number of items in the dataset after the last load
    private int previousTotalItemCount = 0;
    // True if we are still waiting for the last set of data to load.
    private boolean loading = true;
    // Sets the starting page index
    private int startingPageIndex = 0;

    public EndlessScrollListener() {
    }

    public EndlessScrollListener(int visibleThreshold) {
        this.visibleThreshold = visibleThreshold;
    }

    public EndlessScrollListener(int visibleThreshold, int startPage) {
        this.visibleThreshold = visibleThreshold;
        this.startingPageIndex = startPage;
        this.currentPage = startPage;
    }

    // This happens many times a second during a scroll, so be wary of the code you place here.
    // We are given a few useful parameters to help us work out if we need to load some more data,
    // but first we check if we are waiting for the previous load to finish.
    @Override
    public void onScroll(AbsListView view,int firstVisibleItem,int visibleItemCount,int totalItemCount) {
        // If the total item count is zero and the previous isn't, assume the
        // list is invalidated and should be reset back to initial state
        if (totalItemCount < previousTotalItemCount) {
            this.currentPage = this.startingPageIndex;
            this.previousTotalItemCount = totalItemCount;
            if (totalItemCount == 0) { this.loading = true; } 
        }

        // If it’s still loading, we check to see if the dataset count has
        // changed, if so we conclude it has finished loading and update the current page
        // number and total item count.
        if (loading && (totalItemCount > previousTotalItemCount)) {
            loading = false;
            previousTotalItemCount = totalItemCount;
            currentPage++;
        }

        // If it isn’t currently loading, we check to see if we have breached
        // the visibleThreshold and need to reload more data.
        // If we do need to reload some more data, we execute onLoadMore to fetch the data.
        if (!loading && (totalItemCount - visibleItemCount)<=(firstVisibleItem + visibleThreshold)) {
            onLoadMore(currentPage + 1, totalItemCount);
            loading = true;
        }
    }

    // Defines the process for actually loading more data based on page
    public abstract void onLoadMore(int page, int totalItemsCount);

    @Override
    public void onScrollStateChanged(AbsListView view, int scrollState) {
        // Don't take any action on changed
    }
}

Answer 3

我认为 raveN 发布的滚动监听器是一个不错的选择。 但在 Android 中处理数据加载的简洁方法是使用 Loader（CursorLoader 或 AsyncTaskLoader，具体取决于您从何处获取数据）。

令人惊讶的是，我找不到任何用加载器进行分页的干净方法，所以我继续创建了一个支持它的基本加载器。这是非常早期的阶段，所以如果您发现错误，请随时提交拉取请求：

https://github.com/nbarraille/paginated_loader

它几乎为加载器添加了一个loadMore() 方法，您只需实现loadInBackground() 来加载单页数据，并实现appendResults() 来告诉加载器如何将结果组合在一起，仅此而已.

示例应用使用无限滚动侦听器请求更多数据，一旦到达列表末尾，就会请求更多数据。