/// <summary>
    /// The base implementation of a command.
    /// </summary>
    abstract class CommandBase : ICommand
    {
        /// <summary>
        /// Occurs when changes occur that affect whether or not the command should execute.
        /// </summary>
        public event EventHandler CanExecuteChanged
        {
            add { System.Windows.Input.CommandManager.RequerySuggested += value; }
            remove { System.Windows.Input.CommandManager.RequerySuggested -= value; }
        }

        /// <summary>
        /// Raises the <see cref="CanExecuteChanged" /> event.
        /// </summary>
        public void OnCanExecuteChanged()
        {
            System.Windows.Input.CommandManager.InvalidateRequerySuggested();
        }

        /// <summary>
        /// Defines the method that determines whether the command can execute in its current state.
        /// </summary>
        /// <param name="parameter">Data used by the command.  If the command does not require data to be passed, this object can be set to null.</param>
        /// <returns>
        /// true if this command can be executed; otherwise, false.
        /// </returns>
        public virtual bool CanExecute(object parameter)
        {
            return true;
        }

        /// <summary>
        /// Defines the method to be called when the command is invoked.
        /// </summary>
        /// <param name="parameter">Data used by the command.  If the command does not require data to be passed, this object can be set to null.</param>
        public void Execute(object parameter)
        {
            if (!CanExecute(parameter))
            {
                return;
            }
            OnExecute(parameter);
        }

        /// <summary>
        /// Executes the command.
        /// </summary>
        /// <param name="parameter">The parameter.</param>
        protected abstract void OnExecute(object parameter);
    }

    /// <summary>
    /// The command that relays its functionality by invoking delegates.
    /// </summary>
    class RelayCommand : CommandBase
    {
        private readonly Action<object> _execute;
        private readonly Func<object, bool> _canExecute;

        /// <summary>
        /// Initializes a new instance of the <see cref="RelayCommand"/> class.
        /// </summary>
        /// <param name="execute">The execute.</param>
        /// <param name="canExecute">The can execute.</param>
        public RelayCommand(Action<object> execute, Func<object, bool> canExecute = null)
        {
            if (canExecute == null)
            {
                // no can execute provided, then always executable
                canExecute = (o) => true;
            }
            this._execute = execute;
            this._canExecute = canExecute;
        }

        /// <summary>
        /// Defines the method that determines whether the command can execute in its current state.
        /// </summary>
        /// <param name="parameter">Data used by the command. If the command does not require data to be passed, this object can be set to null.</param>
        /// <returns>
        /// true if this command can be executed; otherwise, false.
        /// </returns>
        public override bool CanExecute(object parameter)
        {
            return _canExecute == null || _canExecute.Invoke(parameter);
        }

        /// <summary>
        /// Executes the command.
        /// </summary>
        /// <param name="parameter">The parameter.</param>
        protected override void OnExecute(object parameter)
        {
            _execute?.Invoke(parameter);
        }
    }

? 然后，我们实现一个示例，点击 Clear 按钮时，清空 TextBox 中的所有内容，那么需要声明一个 Model 和 ViewModel ，具体实现可以阅读 WPF 之 INotifyPropertyChanged 接口的使用 （一）：

    class Student
    {
        public  string Id { get; set; }
        public string Name { get; set; }
        public string Email { get; set; }
        public string Phone { get; set; }
    }
    class MainWindowVM : NotifyProperty
    {
        private Student _student;

        public Student Student
        {
            get => _student;
            set => SetProperty(ref _student, value);
        }
        public ICommand Clear { get; set; }

        private void ClearCommand(object args)
        {
            Student = new Student();
        }

        public MainWindowVM()
        {
            _student = new Student()
            {
                Id = "01",
                Name = "Dwayne",
                Email = "974608610@qq.com",
                Phone = "180888888888",
            };
            Clear=new RelayCommand(ClearCommand,null);
        }
    }

  <StackPanel Margin="20">
        <Button Margin="10" Height="50" Content="Clear" Command="{Binding Path=Clear}"></Button>
        <TextBox Text="{Binding Student.Id}" Height="50" VerticalContentAlignment="Center" Margin="10" BorderBrush="Black"></TextBox>
        <TextBox Text="{Binding Student.Name}" Height="50" VerticalContentAlignment="Center" Margin="10" BorderBrush="Black"></TextBox>
        <TextBox Text="{Binding Student.Email}" Height="50" VerticalContentAlignment="Center" Margin="10" BorderBrush="Black"></TextBox>
        <TextBox Text="{Binding Student.Phone}" Height="50" VerticalContentAlignment="Center" Margin="10" BorderBrush="Black"></TextBox>
    </StackPanel>

 xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"

  <TextBox Text="改变内容即可删除" Height="50" VerticalContentAlignment="Center" Margin="10" BorderBrush="Black" >
            <i:Interaction.Triggers>
                <i:EventTrigger EventName="TextChanged">
                    <i:InvokeCommandAction Command="{Binding Clear}" CommandParameter="{Binding Path=Student}"/>
                </i:EventTrigger>
            </i:Interaction.Triggers>
        </TextBox>