Observer Pattern以下参考:程序设计: 猫大叫一声,所有的老鼠都开始逃跑,主人被惊醒。(C#语言) 要求: 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。 要点:1. 联动效果,运行代码只要执行Cat.Cryed()方法。2. 对老鼠和主人进行抽象 评分标准: <1>.构造出Cat、Mouse、Master三个类,并能使程序运行(2分) <2>从Mouse和Master中提取抽象(5分) <3>联动效应,只要执行Cat.Cryed()就可以使老鼠逃跑,主人惊醒。(3分) 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(); } }
要求:
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。
要点:1. 联动效果,运行代码只要执行Cat.Cryed()方法。2. 对老鼠和主人进行抽象
评分标准: <1>.构造出Cat、Mouse、Master三个类,并能使程序运行(2分)
<2>从Mouse和Master中提取抽象(5分)
<3>联动效应,只要执行Cat.Cryed()就可以使老鼠逃跑,主人惊醒。(3分)
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();
} }