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前言
wpf中ListBox在针对多个选项选择中的应用十分广泛，本文就来讲解非Mvvm和Mvvm模式下如何使用ListBox。
1、非MVVM模式下
xaml代码：
ListBoxItem用于存储ListBox的每一项，可以设置ListBoxItem的属性，比如Foreground控制项的字体颜色；Background来控制项的背景色；为ListBox注册SelectionChanged事件，该事件代码在MainWindow窗体类中。
<ListBox x:Name="ListBox_test" SelectionChanged="ListBox_SelectionChanged"><ListBoxItem Foreground="White" Background="Red" >项目1</ListBoxItem><ListBoxItem>项目2</ListBoxItem><ListBoxItem>项目3</ListBoxItem><ListBoxItem>项目4</ListBoxItem></ListBox >
MainWindow窗体类
public partial class MainWindow : Window{public MainWindow(){InitializeComponent();this.DataContext = new ViewModel();}private void ListBox_SelectionChanged(object sender, SelectionChangedEventArgs e){var item = ListBox_test.SelectedItem;}}
运行结果：
2、MVVM模式下
2.1 SelectionMode为Single
xaml代码：
1）mvvm模式下使用绑定来为ListBox添加数据，通过为ItemsSource绑定ViewModel中的Items属性
2）然后为了获取ListBox中用户选择的哪一项，为SelectedItem绑定ViewModel中的divisionType属性
但是由于SelectedItem是object类型，divisionType是枚举类型，无法直接绑定，所以要使用类型转换
<Window.Resources><local:DivisionTypeToString x:Key="DivisionTypeToString"/></Window.Resources><ListBox SelectionMode="Single" ItemsSource="{Binding Items }" Foreground="Red" SelectedItem="{Binding divisionType, Converter={StaticResource DivisionTypeToString}}" > </ListBox >
添加类型转换
下面的Convert方法用于将DivisionType转换成字符串，ConvertBack用于将字符串转换成DivisionType
public class DivisionTypeToString: IValueConverter{public object Convert(object value, Type targetType, object parameter, CultureInfo culture){DivisionType divisionType = (DivisionType)value;return divisionType.ToString ();}public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture){DivisionType divisionType =(DivisionType)Enum.Parse(typeof (DivisionType),value .ToString ());return divisionType;}}
添加 Model类
public enum DivisionType
{分时1,分时2
}
添加ViewModelBase类
public class ViewModelBase{public event PropertyChangedEventHandler PropertyChanged;public void OnPropertyChanged(string propname){if (PropertyChanged != null){PropertyChanged(this, new PropertyChangedEventArgs(propname));}}}
添加ViewModel类
public class ViewModel : ViewModelBase{public ViewModel(){Items = new List<string>();Items.Add("分时1");Items.Add("分时2");}private List<string> items;public List<string> Items{get{return items;}set{this.items = value;OnPropertyChanged("Items");}}private DivisionType _divisionType = DivisionType.分时1;public DivisionType divisionType{get{return _divisionType;}set{this._divisionType = value;OnPropertyChanged("divisionType");}}}
运行结果：
2.2 SelectionMode为Multiple
xaml代码：
1）mvvm模式下使用绑定来为ListBox添加数据，通过为ItemsSource绑定ViewModel中的Items属性
2）又因为是多选，所以不能使用SelectedItem属性的绑定，得使用 SelectionChanged事件，然后在事件中获取SelectedItems属性从而获取所有用户选择的项，所以这里使用使用Interaction.Trigger，EventName指定绑定的事件名称，CommandSelectionChanged是绑定的ViewModel中的命令。（这里要注意使用Interaction.Triggers需要引用System.Windows.Interactivity.dll）
<Window.Resources><local:DivisionTypeToString x:Key="DivisionTypeToString"/></Window.Resources><ListBox x:Name="listBox_test2" SelectionMode="Multiple" ItemsSource="{Binding Items }" Foreground="Red" ><Event:Interaction.Triggers><Event:EventTrigger EventName="SelectionChanged"><Event:InvokeCommandAction Command="{Binding CommandSelectionChanged}" CommandParameter="{Binding ElementName=listBox_test2}"/></Event:EventTrigger></Event:Interaction.Triggers></ListBox >
添加DelegateCommand
public class DelegateCommand : ICommand{private readonly Action<object> _execute;private readonly Func<object, bool> _canExecute;public DelegateCommand(Action<object> execute, Func<object, bool> canExecute = null){_execute = execute ?? throw new ArgumentNullException(nameof(execute));_canExecute = canExecute;}public bool CanExecute(object parameter){if (_canExecute != null){return _canExecute(parameter);}else{return true;}}public void Execute(object parameter){_execute(parameter);}public event EventHandler CanExecuteChanged{add => CommandManager.RequerySuggested += value;remove => CommandManager.RequerySuggested -= value;}public void RaiseCanExecuteChanged(){CommandManager.InvalidateRequerySuggested();}}
添加 Model类
public enum DivisionType
{分时1,分时2
}
添加ViewModelBase类
public class ViewModelBase{public event PropertyChangedEventHandler PropertyChanged;public void OnPropertyChanged(string propname){if (PropertyChanged != null){PropertyChanged(this, new PropertyChangedEventArgs(propname));}}}
添加ViewModel类
public class ViewModel : ViewModelBase{public ICommand CommandSelectionChanged { get; set; }public ViewModel(){Items = new List<string>();Items.Add("分时1");Items.Add("分时2");CommandSelectionChanged = new DelegateCommand(ListBoxSelectionChanged);}private List<string> items;public List<string> Items{get{return items;}set{this.items = value;OnPropertyChanged("Items");}}private ObservableCollection<DivisionType> _divisionTypeList = new ObservableCollection<DivisionType>();public ObservableCollection<DivisionType> divisionTypeList{get{return _divisionTypeList;}set{this._divisionTypeList = value;OnPropertyChanged("divisionTypeList");}}private void ListBoxSelectionChanged(object obj){divisionTypeList.Clear();ListBox listBox =(ListBox) obj;foreach ( var item in listBox.SelectedItems){DivisionType divisionType=(DivisionType) Enum.Parse(typeof (DivisionType),item.ToString ());divisionTypeList.Add(divisionType);}}}
运行结果：
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