msdn中 ObservableCollection<class="typeparameter">T> 类 表示一个动态数据集合,在添加项、移除项或刷新整个列表时,此集合将提供通知。
many cases the data that you work with is a collection of objects.">在许多情况下,所使用的数据是对象的集合。 例如,数据绑定中的一个常见方案是使用 ItemsControl(如 ListBox、ListView 或 TreeView)来显示记录的集合。
can enumerate over any collection that implements the <span class="mtpsTagOuterHtml" >IEnumerable interface.">可以枚举实现 IEnumerable 接口的任何集合。 但是,若要设置动态绑定,以便集合中的插入或caozuo.html" target="_blank">删除操作可以自动更新 UI,则该集合必须实现 INotifyCollectionChanged 接口。 此接口公开 CollectionChanged 事件,只要基础集合发生更改,都应该引发该事件。
WPF 提供 ObservableCollection<T> 类,它是实现 INotifyCollectionChanged 接口的数据集合的内置实现。
还有许多情况,我们所使用的数据只是单纯的字段或者属性,此时我们需要为这些字段或属性实现INotifyPropertyChanged接口,实现了该接口,只要字段或属性的发生了改变,就会提供通知机制。
前台xmal
<Window x:Class="WpfApplication1.WindowObservable" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="Window8" Height="356" Width="471"> <Grid> <StackPanel Height="295" HorizontalAlignment="Left" Margin="10,10,0,0" Name="stackPanel1" VerticalAlignment="Top" Width="427"> <TextBlock Height="23" Name="textBlock1" Text="学员编号:" /> <TextBox Height="23" Name="txtStudentId" Width="301" HorizontalAlignment="Left"/> <TextBlock Height="23" Name="textBlock2" Text="学员列表:" /> <ListBox Height="156" Name="lbStudent" Width="305" HorizontalAlignment="Left"> <ListBox.ItemTemplate> <DataTemplate> <StackPanel Name="stackPanel2" Orientation="Horizontal"> <TextBlock Text="{Binding Id,Mode=TwoWay}" Margin="5" Background="Beige"/> <TextBlock Text="{Binding Name,Mode=TwoWay}" Margin="5"/> <TextBlock Text="{Binding Age,Mode=TwoWay}" Margin="5"/> </StackPanel> </DataTemplate> </ListBox.ItemTemplate> </ListBox> <Button Content="Button" Height="23" Name="button1" Width="75" HorizontalAlignment="Left" Click="button1_Click" /> </StackPanel> </Grid> </Window>
后台cs
using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Windows; using System.Windows.Controls; using System.Windows.Data; using System.Windows.Documents; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Imaging; using System.Windows.Shapes; using System.Collections.ObjectModel; using System.ComponentModel; namespace WpfApplication1 { public partial class WindowObservable : Window { ObservableCollection<Students> infos = new ObservableCollection<Students>() { new Students(){ Id=1, Age=11, Name="Tom"}, new Students(){ Id=2, Age=12, Name="Darren"}, new Students(){ Id=3, Age=13, Name="Jacky"}, new Students(){ Id=4, Age=14, Name="Andy"} }; public WindowObservable() { InitializeComponent(); this.lbStudent.ItemsSource = infos; this.txtStudentId.SetBinding(TextBox.TextProperty, new Binding("SelectedItem.Id") { Source = lbStudent }); } private void button1_Click(object sender, RoutedEventArgs e) { infos[1] = new Students() { Id = 4, Age = 14, Name = "这是一个集合改变" }; infos[2].Name = "这是一个属性改变"; } public class Students { public int Id { get; set; } public string Name { get; set; } public int Age { get; set; } } } }
在这个例子中我们将Students数据对象用ObservableCollection<T>来修饰。这样当我们点击click的时候我们看到。当我们点击后只有student整个对象的改变引发了后台通知机制。
INotifyPropertyChanged会向客户端发出某一属性值已更改的通知。当元素属性值改变时,会通知后台model
前台代码不变,我们让后台Students Model实现INotifyPropertyChanged接口。
using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Windows; using System.Windows.Controls; using System.Windows.Data; using System.Windows.Documents; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Imaging; using System.Windows.Shapes; using System.Collections.ObjectModel; using System.ComponentModel; namespace WpfApplication1 { public partial class WindowObservable : Window { ObservableCollection<Students> infos = new ObservableCollection<Students>() { new Students(){ Id=1, Age=11, Name="Tom"}, new Students(){ Id=2, Age=12, Name="Darren"}, new Students(){ Id=3, Age=13, Name="Jacky"}, new Students(){ Id=4, Age=14, Name="Andy"} }; public WindowObservable() { InitializeComponent(); this.lbStudent.ItemsSource = infos; this.txtStudentId.SetBinding(TextBox.TextProperty, new Binding("SelectedItem.Id") { Source = lbStudent }); } private void button1_Click(object sender, RoutedEventArgs e) { infos[1] = new Students() { Id = 4, Age = 14, Name = "这是一个集合改变" }; infos[2].Name = "这是一个属性改变"; } public class Students : INotifyPropertyChanged { string _name; public int Id { get; set; } public string Name { get { return _name; } set { _name = value; OnPropertyChanged("Name"); } } public int Age { get; set; } protected internal virtual void OnPropertyChanged(string propertyName) { if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); } public event PropertyChangedEventHandler PropertyChanged; } } }
此时我们再 运行代码会发现
不管是集合还是对象都发生了改变。至此。我们的整个后台通知就能完美监视任何对象变动。
代码参考:http://blog.csdn.net/fwj380891124/article/details/8194190
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