观察者模式

定义

public interface IAnimal
{
    public string _Name { get; set; }
    void Action();
}

public class Cat : IAnimal
{
    public string _Name { get; set; }

    public Cat(string Name)
    {
        _Name = Name;
    }
    public void Action()
    {
        Console.WriteLine($"小猫{_Name}开始跑");
    }
}

public class Dog : IAnimal
{
    public string _Name { get; set; }

    public Dog(string Name) {
        _Name = Name;
    }

    public void Action()
    {
        Console.WriteLine($"小狗{_Name}开始叫");
    }
}

public delegate void DelegateAction();

public class OwnerDelegate
{
    public void Action()
    {
        Console.WriteLine("主人回来了");
    }
    public OwnerDelegate()
    {
        delegateAction = new DelegateAction(Action);
    }
    public DelegateAction delegateAction;
    public void AddAction(DelegateAction action)
    {
        delegateAction += action;
    }
    public void RemoveAction(DelegateAction action)
    {
        if (delegateAction != null)
        {
            delegateAction -= action;
        }
    }
    public void Update()
    {
        delegateAction.Invoke();
    }
}

public class Owner
{ 
    public List<IAnimal> animals = new List<IAnimal>();
    public void Addanimal(IAnimal animal)
    {
        animals.Add(animal);
    }
    public void Removeanimal(IAnimal animal)
    {
        animals.Remove(animal);
    }
    public void Aciton()
    {
        Console.WriteLine("主人回家了");
        foreach (var item in animals)
        {
            item.Action();
        }
    }
}

调用

Console.WriteLine("观察者模式");
Cat cat = new Cat("Jim");
Dog dog = new Dog("Tom");
Owner owner = new Owner();
owner.Addanimal(cat);
owner.Addanimal(dog);
owner.Aciton();
Console.WriteLine("观察者模式,委托实现");
Cat cat1 = new Cat("Jim");
Dog dog1 = new Dog("Tom");
OwnerDelegate ownerDelegate = new OwnerDelegate();
ownerDelegate.AddAction(cat1.Action);
ownerDelegate.AddAction(dog1.Action);
ownerDelegate.Update();