public interface ISupportIncrementalLoading{Task<LoadMoreItemsResult> LoadMoreAsync(uint count);}

　public abstract class IncrementalLoadingDataSource<T> : ObservableCollection<T>, ISupportIncrementalLoading{public async Task<LoadMoreItemsResult> LoadMoreAsync(uint count){if (CanLoadMore()){ICollection<T> list = await LoadMore(count);foreach (var item in list){this.Add(item);}return new LoadMoreItemsResult() { LoadedCount = list.Count };}else{return new LoadMoreItemsResult() { LoadedCount = 0 };;}}protected abstract Task<ICollection<T>> LoadMore(uint count);protected abstract bool CanLoadMore();}

public class StudentInfo{public string Name { get; set; }}public class Students : IncrementalLoadingDataSource<StudentInfo>{protected async override Task<ICollection<StudentInfo>> LoadMore(uint count){return await Task.Factory.StartNew<ICollection<StudentInfo>>(() => {List<StudentInfo> list = new List<StudentInfo>();for (int i = 0; i < count; i++){list.Add(new StudentInfo() { Name = i.ToString() });}return list;});}protected override bool CanLoadMore(){return true;}}

public class IncrementalLoadingHelper{public const uint PAGE_SIZE = 25;public static DependencyProperty IncrementalLoadingProperty =DependencyProperty.RegisterAttached("IncrementalLoading", typeof(Boolean), typeof(IncrementalLoadingHelper), new PropertyMetadata(false, IncrementalLoadingPropertyChangedCallback));private static ItemsControl _itemsControl;public static void SetIncrementalLoading(DependencyObject obj, bool val){obj.SetValue(IncrementalLoadingProperty, val);}public static bool GetIncrementalLoading(DependencyObject obj){return (bool)obj.GetValue(IncrementalLoadingProperty);}private static void IncrementalLoadingPropertyChangedCallback(DependencyObject d, DependencyPropertyChangedEventArgs e){ItemsControl control = d as ItemsControl;ScrollBar scrollBar = GetChild<ScrollBar>(d);if (control != null && scrollBar != null && control.Items.Count > 0){scrollBar.Tag = control;_itemsControl = control;var isupport = control.ItemsSource as  ISupportIncrementalLoading;if (isupport != null){scrollBar.ValueChanged += scrollBar_ValueChanged;}}}static async void scrollBar_ValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e){ScrollBar scrollBar = sender as ScrollBar;double max = (double)scrollBar.GetValue(ScrollBar.MaximumProperty);if (e.NewValue + 1 >= max){var control = scrollBar.Tag as ItemsControl;if (control != null){var result = await ((ISupportIncrementalLoading)control.ItemsSource).LoadMoreAsync(PAGE_SIZE);}}}public static T GetChild<T>(DependencyObject element) where T : DependencyObject{T result = null;Queue<DependencyObject> quene = new Queue<DependencyObject>();quene.Enqueue(element);while (quene.Count > 0){DependencyObject ele = quene.Dequeue();int count = VisualTreeHelper.GetChildrenCount(ele);for (int i = 0; i < count; i++){DependencyObject child = VisualTreeHelper.GetChild(ele, i);result = child as T;if (result != null) return result;quene.Enqueue(child);}}return result;}}

 private void LayoutRoot_Loaded(object sender, RoutedEventArgs e){lstStudent.SetValue(IncrementalLoadingHelper.IncrementalLoadingProperty, true);}public async void LoadData(){var data = new Students();await data.LoadMoreAsync(IncrementalLoadingHelper.PAGE_SIZE);lstStudent.ItemsSource = data;}