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。
1、运用接口：
代码
public interface Observer {
void Response(); //观察者的响应，这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
}
/// <summary>
/// 老鼠的相应，继承被观察的对象
/// </summary>
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!");
}
}
/// <summary>
/// 主人的相应，继承被观察的对象
/// </summary>
public class Master : Observer {
public Master(Subject subj) {
subj.AimAt(this);
}
public void Response() {
Console.WriteLine("Host waken!");
}
}
/// <summary>
/// 猫观充当观察者的角色
/// </summary>
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();
}
}
2、 使用event -- delegate设计..
代码
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();
}
}