将视图模型中的抽象命令作为XAML / MVVM项目的一个有价值的实践.我明白了.而且,我在WinRT中看到ICommand;但是,我们如何实现呢？我没有找到一个实际工作的样本.有人知道吗
我所有的时间最喜欢的都是由PnP团队提供的DelegateCommand.它允许您创建一个键入的命令：
MyCommand = new DelegateCommand<MyEntity>(OnExecute);
...
private void OnExecute(MyEntity entity)
{...}
它还允许提供一种方法来提升CanExecuteChanged事件(禁用/启用命令)
MyCommand.RaiseCanExecuteChanged();
以下是代码：
public class DelegateCommand<T> : ICommand
{
private readonly Func<T,bool> _canExecuteMethod;
private readonly Action<T> _executeMethod;
#region Constructors
public DelegateCommand(Action<T> executeMethod)
: this(executeMethod,null)
{
}
public DelegateCommand(Action<T> executeMethod,Func<T,bool> canExecuteMethod)
{
_executeMethod = executeMethod;
_canExecuteMethod = canExecuteMethod;
}
#endregion Constructors
#region ICommand Members
public event EventHandler CanExecuteChanged;
bool ICommand.CanExecute(object parameter)
{
try
{
return CanExecute((T)parameter);
}
catch { return false; }
}
void ICommand.Execute(object parameter)
{
Execute((T)parameter);
}
#endregion ICommand Members
#region Public Methods
public bool CanExecute(T parameter)
{
return ((_canExecuteMethod == null) || _canExecuteMethod(parameter));
}
public void Execute(T parameter)
{
if (_executeMethod != null)
{
_executeMethod(parameter);
}
}
public void RaiseCanExecuteChanged()
{
OnCanExecuteChanged(EventArgs.Empty);
}
#endregion Public Methods
#region Protected Methods
protected virtual void OnCanExecuteChanged(EventArgs e)
{
var handler = CanExecuteChanged;
if (handler != null)
{
handler(this,e);
}
}
#endregion Protected Methods
}
