问使用VBA模拟Java 8 (Excel)

EN

    public abstract class Duck {
    FlyBehavior flyBehavior;
    QuackBehavior quackBehavior;

    public Duck() {
    }

    public void setFlyBehavior(FlyBehavior fb) {
        flyBehavior = fb;
    }

    public void setQuackBehavior(QuackBehavior qb) {
        quackBehavior = qb;
    }

    abstract void display();

    public void performFly() {
        flyBehavior.fly();
    }

    public void performQuack() {
        quackBehavior.quack();
    }

    public void swim() {
        System.out.println("All ducks float, even decoys!");
    }

    public class MallardDuck extends Duck {

    public MallardDuck() {

        quackBehavior = new Quack();
        flyBehavior = new FlyWithWings();

    }

    public void display() {
        System.out.println("I'm a real Mallard duck");
    }
}

    public class MiniDuckSimulator {

    public static void main(String[] args) {

        MallardDuck mallard = new MallardDuck();
        FlyBehavior cantFly = () -> System.out.println("I can't fly");
        QuackBehavior squeak = () -> System.out.println("Squeak");
        RubberDuck  rubberDuckie = new RubberDuck(cantFly, squeak);
        DecoyDuck   decoy = new DecoyDuck();

        Duck     model = new ModelDuck();

        mallard.performQuack();
        rubberDuckie.performQuack();
        decoy.performQuack();

        model.performFly(); 
        model.setFlyBehavior(new FlyRocketPowered());
        model.performFly();
    }
}

'@Folder("SimUDuck.Objects.HeadFirst")
Option Explicit
Private Type TObject
    FlyBehavior As IFlyBehavior
    QuackBehavior As IQuackBehavior
    DuckModel As IDuckModel
End Type
Private this As TObject

Private Sub Class_Terminate()
    With this
        Set .FlyBehavior = Nothing
        Set .QuackBehavior = Nothing
    End With
End Sub

Public Property Get DuckModel() As IDuckModel
    Set DuckModel = this.DuckModel
End Property
Public Property Set DuckModel(ByVal model As IDuckModel)
    With this
        Set .DuckModel = model
    End With
End Property
Public Property Get FlyBehavior() As IFlyBehavior
    Set FlyBehavior = this.FlyBehavior
End Property
Public Property Set FlyBehavior(ByVal behavior As IFlyBehavior)
    Set this.FlyBehavior = behavior
End Property
Public Property Get QuackBehavior() As IQuackBehavior
    Set QuackBehavior = this.QuackBehavior
End Property
Public Property Set QuackBehavior(ByVal behavior As IQuackBehavior)
    Set this.QuackBehavior = behavior
End Property

Public Sub performFly()
    this.FlyBehavior.Fly
End Sub
Public Sub performQuack()
    this.QuackBehavior.Quack
End Sub

Public Sub Swim()
    'todo
End Sub
Public Sub Display()
    this.DuckModel.Display
End Sub

'@PredeclaredId
'@Folder("SimUDuck.Models.HeadFirst")
Option Explicit
Private Type TModel
    Display As String
End Type
Private this As TModel
Implements IDuckModel
Private Sub IDuckModel_Display()
    Debug.Print this.Display '"I'm A Mallard Duck"
End Sub

Public Function CreateDuck(ByVal duck As DuckObject) As IDuckModel
    With duck
        Set .FlyBehavior = New FlyWithWingsBehavior
        Set .QuackBehavior = New QuackBehavior
    End With
    With New MallardDuckModel
        .Display = "I'm A Mallard Duck"
        Set CreateDuck = .Self
    End With
End Function
Public Property Get Self() As IDuckModel
    Set Self = Me
End Property
Public Property Get Display() As String
    Display = this.Display
End Property
Public Property Let Display(ByVal value As String)
    this.Display = value
End Property

Public Sub MainDuck()
    Dim duck As DuckObject
    Set duck = New DuckObject
    With New MallardDuckModel
        Dim model As IDuckModel
        Set model = .CreateDuck(duck)
    End With
    With duck
        Set .DuckModel = model
        .performFly
        .performQuack
        .Display
        Dim FlyBehavior As IFlyBehavior
        Set FlyBehavior = New FlyRocketPoweredBehavior
        Set .FlyBehavior = FlyBehavior
        Dim QuackBehavior As IQuackBehavior
        Set QuackBehavior = New SqueakBehavior
        Set .QuackBehavior = QuackBehavior
        .performFly
        .performQuack
        .Display
    End With
    Set duck = New DuckObject
    With New ModelDuckModel
        Set model = .CreateDuck(duck)
    End With
    With duck
        Set .DuckModel = model
        .performFly
        .performQuack
        .Display
    End With
End Sub