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WPF采用MVVM模式命令绑定

程序员文章站 2022-06-07 15:13:55
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<Window x:Class="WpfBing.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:vm="clr-namespace:WpfBing"
        xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <Grid.DataContext>
            <vm:ViewModel/>
        </Grid.DataContext>
        <TextBox Text="{Binding Name,UpdateSourceTrigger=PropertyChanged}"  Width="150" Height="30">
            <i:Interaction.Triggers>
                <i:EventTrigger EventName="TextChanged">
                    <i:InvokeCommandAction Command="{Binding NameChanged}" />
                </i:EventTrigger>
            </i:Interaction.Triggers>
        </TextBox>
        <Button Content="测试" Command="{Binding UpdateData}" Width="150" Height="40" HorizontalAlignment="Right">
        </Button>
    </Grid>
</Window>

说明:

 xmlns:vm="clr-namespace:WpfBing"添加对命名空间的引用,主要是让前台页面能够寻找到viewmodel的命名空间;
xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity" 添加wpf的命名控件引用,主要是用来提供使用该命名空间中的触发器绑定命令
该类的下载链接为:System.Windows.Interactivity
<Grid.DataContext>   <vm:ViewModel/> </Grid.DataContext> 数据源绑定,将该空间按的数据源绑定为vm空间下的ViewModel对象上;注:纯前台绑定的关键
 <i:Interaction.Triggers>
    <i:EventTrigger EventName="TextChanged">
       <i:InvokeCommandAction Command="{Binding NameChanged}" />
     </i:EventTrigger>
</i:Interaction.Triggers>
通过触发器实现对控件事件的命令绑定,该代码需要添加System.Windows.Interactivity.dll的引用
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Input;

namespace WpfBing
{
    public class RelayCommand : ICommand
    {
        #region 字段
        readonly Func<Boolean> _canExecute;
        readonly Action _execute;
        #endregion

        #region 构造函数
        public RelayCommand(Action execute)
            : this(execute, null)
        {
        }

        public RelayCommand(Action execute, Func<Boolean> canExecute)
        {
            if (execute == null)
                throw new ArgumentNullException("execute");
            _execute = execute;
            _canExecute = canExecute;
        }
        #endregion

        #region ICommand的成员
        public event EventHandler CanExecuteChanged
        {
            add
            {

                if (_canExecute != null)
                    CommandManager.RequerySuggested += value;
            }
            remove
            {

                if (_canExecute != null)
                    CommandManager.RequerySuggested -= value;
            }
        }

        [DebuggerStepThrough]
        public Boolean CanExecute(Object parameter)
        {
            return _canExecute == null ? true : _canExecute();
        }

        public void Execute(Object parameter)
        {
            _execute();
        }
        #endregion
    }
}

说明:该段代码主要实现ICommand命令,实现该命令接口,通过委托调用调用ViewModel中相应的方法;

ICommand主要有两个方法,Excute,CanExcute,一个是调用的实现方法,一个是判断是否执行该调用方法;

注:功能上可以用来控制按钮或其他,控件状态是否可用

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

namespace WpfBing
{
    public class ViewModel:INotifyPropertyChanged
    {

        public event PropertyChangedEventHandler PropertyChanged;

        public void Notify(string name)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(name));
            }

        }
        private string name = "测试数据";

        public string Name
        {
            get { return name; }
            set
            {
                name = value;
                Notify("Name");
            }
        }
        void UpdateArtistNameExecute()
        {
            this.Name = "中孝介";
        }

        bool CanUpdateArtistNameExecute()
        {
            return true;
        }
        public ICommand UpdateData { get { return new RelayCommand(UpdateArtistNameExecute, CanUpdateArtistNameExecute); } }
        public ICommand NameChanged { get { return new RelayCommand(NameChang); } }

        private void NameChang()
        {
            string na = Name;
        }
    }
}

 

相关标签: WPF MVVM