WPF学习(6) -- WPF命令和通知

news2024/9/24 5:22:34

一、WPF命令

1.ICommand代码

创建一个文件夹和文件

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Input;

namespace 学习.Command
{
    public class MyCommand : ICommand
    {
         Action executeAction;

         public MyCommand(Action action)
         {
             executeAction = action;
         }

        public event EventHandler CanExecuteChanged;

        public bool CanExecute(object parameter)
        {
            return true;
        }

        public void Execute(object parameter)
        {
            executeAction();
        }
    }
}

2.view model代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using 学习.Command;

namespace 学习.ViewModels
{
    public class MainViewModel
    {
        public MyCommand ShowCommand {  get; set; }
        public string Name { get; set; }

        public MainViewModel()
        {
            Name = "Hellow";
            ShowCommand = new MyCommand(Show);
        }

        public void Show()
        {
            Name = "点击了按钮";
            MessageBox.Show(Name);
        }
    }
}

3.xaml.cs代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
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.Navigation;
using System.Windows.Shapes;
using System.Collections.ObjectModel;
using 学习.ViewModels;

namespace 学习
{
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();

            this.DataContext = new MainViewModel();
        }
    }

}

4.xaml代码

<Window x:Class="学习.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:学习.ViewModels"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">

    <Grid>
        <StackPanel>
            <TextBox Text="{Binding Name}"/>
            <Button Content="SHOW" Command="{Binding ShowCommand}"/>
        </StackPanel>
    </Grid>
</Window>

4.结果

点击按钮之后Hellow并没有改变

二、通知更改

创建Base文件放置

1.ViewModelBase代码

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using System.Threading.Tasks;

namespace 学习
{
    public class ViewModelBase : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;
   
        public void OnPropertyChanged([CallerMemberName]string propertyName = "")
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}

2.view model代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using 学习.Command;

namespace 学习.ViewModels
{
    public class MainViewModel : ViewModelBase
    {
        public MyCommand ShowCommand {  get; set; }

        private string _name;
        public string Name
        {
            get { return _name; }
            set
            {
                _name = value;
                OnPropertyChanged();
            }
        }

        public MainViewModel()
        {
            Name = "Hellow";
            ShowCommand = new MyCommand(Show);
        }

        public void Show()
        {
            Name = "点击了按钮";
            MessageBox.Show(Name);
        }
    }
}