Android ListView setOnScrollListener

Question

我的setOnScrollListener有问题。每当我滚动到列表视图的底部时，它就会一直调用我的asynctask。如何设置setOnScrollListener只在我到达底部时才加载。

listview.setAdapter(adapter);
            mProgressDialog.dismiss();

            listview.setOnScrollListener(new OnScrollListener() {

                @Override
                public void onScrollStateChanged(AbsListView view,
                        int scrollState) { // TODO Auto-generated method stub

                }

                @Override
                public void onScroll(AbsListView view, int firstVisibleItem,
                        int visibleItemCount, int totalItemCount) {
                    int lastInScreen = firstVisibleItem + visibleItemCount;
                    if (lastInScreen == totalItemCount) {

                        new loadmore().execute();

                    } else {

                    }

                }
            });

Answer 1

每当您向下滚动列表视图时都会调用OnScroll方法，因此最好的选择是使用某种填充，例如实现here的填充。

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) {
    }
}

visibleThreshold - 在加载更多内容之前，当前滚动位置下方的最小项目数量。

currentPage - 您已加载的当前数据页

previousTotal - 上次加载后数据集中的项目总数

loading - 如果我们仍在等待加载最后一组数据，则为True。