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C#经典机试题(猫叫)

来源: 博客园  发布时间: 2009-10-30 11:21  阅读: 6158 次  推荐: 2   [收藏]  

  猫大叫一声,所有的老鼠都开始逃跑,主人被惊醒。(C#语言)

  1.要有联动性,老鼠和主人的行为是被动的。

  2.考虑可扩展性,猫的叫声可能引起其他联动效应。

 

public interface Observer
{
void Response(); //观察者的响应,如是老鼠见到猫的反映
}
public interface Subject
{
void AimAt(Observer obs); //针对哪些观察者,这里指猫的要扑捉的对象---老鼠
}
public class Mouse : Observer
{
private string name;
public Mouse(string name, Subject subj)
{
this.name = name;
subj.AimAt(
this);
}

public void Response()
{
Console.WriteLine(name
+ " attempt to escape!");
}
}
public class Master : Observer
{
public Master(Subject subj)
{
subj.AimAt(
this);
}

public void Response()
{
Console.WriteLine(
"Host waken!");
}
}

public class Cat : Subject
{
private ArrayList observers;
public Cat()
{
this.observers = new ArrayList();
}
public void AimAt(Observer obs)
{
this.observers.Add(obs);
}
public void Cry()
{
Console.WriteLine(
"Cat cryed!");
foreach (Observer obs in this.observers)
{
obs.Response();
}
}
}
class MainClass
{
static void Main(string[] args)
{
Cat cat
= new Cat();
Mouse mouse1
= new Mouse("mouse1", cat);
Mouse mouse2
= new Mouse("mouse2", cat);
Master master
= new Master(cat);
cat.Cry();
}
}

//------------------------------------------------------------
设计方法二: 使用event -- delegate设计..
public delegate void SubEventHandler();
public abstract class Subject
{
public event SubEventHandler SubEvent;
protected void FireAway()
{
if (this.SubEvent != null)
this.SubEvent();
}
}
public class Cat : Subject
{
public void Cry()
{
Console.WriteLine(
"cat cryed.");
this.FireAway();
}
}
public abstract class Observer
{
public Observer(Subject sub)
{
sub.SubEvent
+= new SubEventHandler(Response);
}
public abstract void Response();
}
public class Mouse : Observer
{
private string name;
public Mouse(string name, Subject sub) : base(sub)
{
this.name = name;
}
public override void Response()
{
Console.WriteLine(name
+ " attempt to escape!");
}
}
public class Master : Observer
{
public Master(Subject sub) : base(sub){}
public override void Response()
{
Console.WriteLine(
"host waken");
}
}
class Class1
{
static void Main(string[] args)
{
Cat cat
= new Cat();
Mouse mouse1
= new Mouse("mouse1", cat);
Mouse mouse2
= new Mouse("mouse2", cat);
Master master
= new Master(cat);
cat.Cry();
}
}

 

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