[銀光] 使用Command和CommandParameter

雖然到現在我還是不太懂對於 Button 使用 Command 跟 Click_Event 有什麼差別...
一樣是使用 Prism & MEF，Command 的部分是用 Prism.Commands

小小的寫個 Demo，輸入名字送出會透過 Command 執行 function 並且傳遞 CommandParameter 的值，顯示 Hello XXX，若沒輸入名字則會顯示 Hello Stranger

Xmal

<Button Content="Submit" Command="{Binding btnCommand}" CommandParameter="{Binding ElementName=tbName}" />

<sdk:Label Content="Hello" />

<sdk:Label Name="lbName" Content="{Binding Name}" />

xmal.cs

public View()

{

    InitializeComponent();

    ViewModel model = new ViewModel();

    this.DataContext = model;

}

ViewModelBase.cs (只是把值變更時的 PropertyChanged 抽出來)

public class ViewModelBase : INotifyPropertyChanged

{

    public event PropertyChangedEventHandler PropertyChanged;

    protected void OnPropertyChanged(string propertyName)

    {

        if (PropertyChanged != null)

        {

            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));

        }

    }

}

ViewModel.cs

public class ViewModel : ViewModelBase

{

    public ICommand btnCommand { get; private set; }

    private bool CanSubmit(object arg) { return true; }



    private string _name;

    public string Name

    {

        get

        {

            return _name;

        }

        set

        {

            _name = value;

            OnPropertyChanged("Name");

        }

    }

    public ViewModel()

    {

        this.btnCommand = new DelegateCommand<object>(this.Exec, this.CanSubmit);

    }

    private void Exec(object o)

    {

        TextBox tb = (TextBox)o;

        if (String.IsNullOrEmpty(tb.Text))

        {

            Name = "Stranger";

        }

        else

        {

            Name = tb.Text;

        }

    }

}

Sample Code 下載 - file name: Demo_ICommand.rar