13、UsingDelegateCommands-MVVM WPF命令的使用

　　1、将App.xaml中的StartupUri="MainWindow.xaml"删除。

　　2、使用NuGet安装Prism.Wpf、Prism.Core、Prism.Unity。

　　3、添加类“Bootstrapper”，编辑如下：

 1 using Microsoft.Practices.Unity;
 2 using Prism.Unity;
 3 using System.Windows;
 4 using BootstrapperShell.Views;
 5 
 6 namespace BootstrapperShell
 7 {
 8     public class Bootstrapper : UnityBootstrapper
 9     {
10         protected override DependencyObject CreateShell()
11         {
12             return Container.Resolve<MainWindow>();
13         }
14 
15         protected override void InitializeShell()
16         {
17             Application.Current.MainWindow.Show();
18         }
19     }
20 }

　　4、创建文件夹Views，将MainWindow.xaml移动到此文件夹中。创建文件夹ViewModels，新建类MainWindowViewModel.cs。注意：VM类的名称一定是V+“ViewModel”，例如MainWindow+“ViewModel”。

　　　　

<Window x:Class="UsingDelegateCommands.Views.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:UsingDelegateCommands"
        xmlns:prism="http://prismlibrary.com/"
        prism:ViewModelLocator.AutoWireViewModel="True"
        mc:Ignorable="d"
        Title="Using DelegateCommand" Width="350" Height="275">
    <StackPanel HorizontalAlignment="Center" VerticalAlignment="Center">
        <CheckBox IsChecked="{Binding IsEnabled}" Content="Can Execute Command" Margin="10"/>
        <Button Command="{Binding ExecuteDelegateCommand}" Content="DelegateCommand" Margin="10"/>
        <Button Command="{Binding DelegateCommandObservesProperty}" Content="DelegateCommand ObservesProperty" Margin="10" Background="#FFD6D6D6"/>
        <Button Command="{Binding DelegateCommandObservesCanExecute}" Content="DelegateCommand ObservesCanExecute" Margin="10"/>
        <Button Command="{Binding ExecuteGenericDelegateCommand}" CommandParameter="Passed Parameter" Content="DelegateCommand Generic" Margin="10"/>
        <TextBlock Text="{Binding UpdateText}" Margin="10" FontSize="22"/>
    </StackPanel>
</Window>

 

using System;
using Prism.Commands;
using Prism.Mvvm;

namespace UsingDelegateCommands.ViewModels
{
    public class MainWindowViewModel:BindableBase
    {
        private bool _isEnabled;
        public bool IsEnabled
        {
            get { return _isEnabled; }
            set
            {
                SetProperty(ref _isEnabled, value);
                //增加执行监控
                ExecuteDelegateCommand.RaiseCanExecuteChanged();
            }
        }

        private string _updateText;
        public string UpdateText
        {
            get { return _updateText; }
            set { SetProperty(ref _updateText, value); }
        }

        public DelegateCommand ExecuteDelegateCommand { get; private set; }
        public DelegateCommand<string> ExecuteGenericDelegateCommand { get; private set; }
        public DelegateCommand DelegateCommandObservesProperty { get; private set; }
        public DelegateCommand DelegateCommandObservesCanExecute { get; private set; }

        public MainWindowViewModel()
        {
            ExecuteDelegateCommand = new DelegateCommand(Execute, CanExecute);

            DelegateCommandObservesProperty = new DelegateCommand(Execute, CanExecute).ObservesProperty(() => IsEnabled);

            DelegateCommandObservesCanExecute = new DelegateCommand(Execute).ObservesCanExecute(() => IsEnabled);

            ExecuteGenericDelegateCommand = new DelegateCommand<string>(ExecuteGeneric).ObservesCanExecute(() => IsEnabled);
        }

        private void Execute()
        {
            UpdateText = $"Updated:{DateTime.Now}";
        }

        private void ExecuteGeneric(string parameter)
        {
            UpdateText = parameter;
        }

        private bool CanExecute()
        {
            return IsEnabled;
        }
    }
}

　　5、修改App.xaml

 1 using System.Collections.Generic;
 2 using System.Configuration;
 3 using System.Data;
 4 using System.Linq;
 5 using System.Threading.Tasks;
 6 using System.Windows;
 7 
 8 namespace BootstrapperShell
 9 {
10     /// <summary>
11     /// App.xaml 的交互逻辑
12     /// </summary>
13     public partial class App : Application
14     {
15         protected override void OnStartup(StartupEventArgs e)
16         {
17             base.OnStartup(e);
18 
19             var bootstrapper = new Bootstrapper();
20             bootstrapper.Run();
21         }
22     }
23 }

 　　6、最终结果：