wpf-mvvm的冗余ICommand类

我仍在学习wpf，但我熟悉如何在wpf c#中设置mvvm。然而，当谈到ICommand/RerelayCommand的东西时，这对我来说有点令人困惑。在过去的几个月里，我编译了一些ICommand类的实现，以便创建我的工具。然而，我现在已经读了几篇文章，并且已经看了足够长的代码，我正在寻找一个人来帮助我，并简单地介绍这里发生了什么，如果是这样，我如何组合/清理这些类。目前，代码似乎是多余的，我不知道如何进行优化。希望这不会要求太多。谢谢

在这篇文章中，我想维护的两件重要的事情是向命令传递参数的能力，如RelayCommand的第一个使用示例所示。第二，启用/禁用第二个命令中的命令的能力。

所以在我的工具中，我有一个helper类。1.我不明白这个RelayCommand.cs中两个类的用法有什么不同。有一个公共类和一个内部类。2.两者都需要吗？还是可以合并？RelayCommand.cs

using System;
using System.Windows.Input;
namespace WpfApplication1.Helper
{
    public class RelayCommand<T> : ICommand
    {
        private readonly Action<T> execute;
        private readonly Predicate<T> canExecute;
        public RelayCommand(Action<T> execute, Predicate<T> canExecute = null)
        {
            if (execute == null)
                throw new ArgumentNullException("execute");
            this.execute = execute;
            this.canExecute = canExecute;
        }
        public bool CanExecute(object parameter)
        {
            if (parameter == null)
            {
                return true;
            }
            else
            {
                return canExecute == null || canExecute((T)parameter);
            }
        }
        public void Execute(object parameter)
        {
            execute((T)parameter);
        }
        public event EventHandler CanExecuteChanged
        {
            add { CommandManager.RequerySuggested += value; }
            remove { CommandManager.RequerySuggested -= value; }
        }
    }
    // added
    internal class RelayCommand : ICommand
    {
        private readonly Predicate<object> canExecute;
        private readonly Action<object> execute;
        public RelayCommand(Action<object> execute, Predicate<object> canExecute = null)
        {
            if (execute == null)
                throw new ArgumentNullException("execute");
            this.execute = execute;
            this.canExecute = canExecute;
        }
        public bool CanExecute(object parameter)
        {
            return canExecute == null || canExecute(parameter);
        }
        public void Execute(object parameter)
        {
            execute(parameter);
        }
        public event EventHandler CanExecuteChanged
        {
            add { CommandManager.RequerySuggested += value; }
            remove { CommandManager.RequerySuggested -= value; }
        }
    }
}

我在名为Customer.cs 的类对象中使用RelayCommand.cs的示例

private ICommand addNewLicense_Command;
public ICommand AddNewLicense_Command
{
    get
    {
        return addNewLicense_Command ?? (addNewLicense_Command = new RelayCommand<Customer>(n =>
        {
            AddNewLicense_Execute(n);
        }));
    }
}

因此，在我的MainViewModel.cs中，在我上面提到的Helper类所属的同一项目中，我有另一个ICommand类。这门课有必要吗？它似乎与RelayCommand类非常相似。

public class CommandHandler : ICommand
{
    private Action _action;
    private bool _canExecute;
    public CommandHandler(Action action, bool canExecute)
    {
        _action = action;
        _canExecute = canExecute;
    }
    public bool CanExecute(object parameter)
    {
        return _canExecute;
    }
    public event EventHandler CanExecuteChanged;
    public void Execute(object parameter)
    {
        _action();
    }
}

我在MainViewModel.cs 中使用CommandHandler的示例

private ICommand addNewUser_Command;
public ICommand AddNewUser_Command
{
    get
    {
        return addNewUser_Command ?? (addNewUser_Command = new CommandHandler(() => AddNewUser_Execute(), true));
    }
}

public ICommand OkCommand { get { return new RelayCommand(Ok); } }
protected virtual void Ok()
{
    // ... do something ...
}

<Button Content="Ok" Command="{Binding OkCommand}" IsDefault="True" />

public ICommand OpenClientCommand { get { return new RelayCommand<Client>(OnOpenClient); } }
private void OnOpenClient(Client client)
{
    // ... do something with client ...
}

<Button Content="Open" Command="{Binding OpenClientCommand}" CommandParameter="{Binding SelectedClient}"/>

<i:Interaction.Triggers>
    <i:EventTrigger EventName="Closing">
        <cmd:EventToCommand Command="{Binding ClosingCommand}" PassEventArgsToCommand="True" />
    </i:EventTrigger>
</i:Interaction.Triggers>

public ICommand ClosingCommand { get { return new RelayCommand<CancelEventArgs>(OnClosing); } }
private void OnClosing(CancelEventArgs args)
{
    if (!PromptUserForClose())
        args.Cancel = true;
}

return addNewLicense_Command ?? (addNewLicense_Command = new RelayCommand<Customer>(n =>
    {
        AddNewLicense_Execute(n);
    },AllowAddNeLicense));
...
bool AllowAddNewLicense() 
{
    return _allowAddEnabled;
}