1、类图
观察者模式结构：
实例类图
2、创建项目
…………………………
3、 AllyControlCenter：指挥部（战队控制中心）类，充当抽象目标类
using System;
using System.Collections.Generic;
namespace ObserverSample
{
abstract class AllyControlCenter
{
protected string allyName; //战队名称
protected List<IObserver> players = new List<IObserver>(); //定义一个集合用于存储战队成员
public void SetAllyName(string allyName)
{
this.allyName = allyName;
}
public string GetAllyName()
{
return this.allyName;
}
//注册方法
public void Join(IObserver obs)
{
Console.WriteLine("{0}加入{1}战队！", obs.Name, this.allyName);
players.Add(obs);
}
//注销方法
public void Quit(IObserver obs)
{
Console.WriteLine("{0}退出{1}战队！", obs.Name, this.allyName);
players.Remove(obs);
}
//声明抽象通知方法
public abstract void NotifyObserver(string name);
}
}
4、 ConcreteAllyControlCenter：具体指挥部类，充当具体目标类
using System;
namespace ObserverSample
{
class ConcreteAllyControlCenter : AllyControlCenter
{
public ConcreteAllyControlCenter(string allyName)
{
Console.WriteLine("{0}战队组建成功！", allyName);
Console.WriteLine("----------------------------");
this.allyName = allyName;
}
//实现通知方法
public override void NotifyObserver(string name)
{
Console.WriteLine("{0}战队紧急通知，盟友{1}遭受敌人攻击！", this.allyName, name);
//遍历观察者集合，调用每一个盟友（自己除外）的支援方法
foreach(object obs in players)
{
if (!((IObserver)obs).Name.Equals(name))
{
((IObserver)obs).Help();
}
}
}
}
}
5、 IObserver：抽象观察者类
namespace ObserverSample
{
interface IObserver
{
string Name
{
get;
set;
}
void Help(); //声明支援盟友方法
void BeAttacked(AllyControlCenter acc); //声明遭受攻击方法
}
}
6、 Player：战队成员类，充当具体观察者类
using System;
namespace ObserverSample
{
class Player : IObserver
{
private string name;
public Player(string name)
{
this.name = name;
}
public string Name
{
get { return name; }
set { name = value; }
}
//支援盟友方法的实现
public void Help()
{
Console.WriteLine("坚持住，{0}来救你！", this.name);
}
//遭受攻击方法的实现，当遭受攻击时将调用战队控制中心类的通知方法NotifyObserver()来通知盟友
public void BeAttacked(AllyControlCenter acc)
{
Console.WriteLine("{0}被攻击！", this.name);
acc.NotifyObserver(name);
}
}
}
7、 Program：客户端测试类
using System;
namespace ObserverSample
{
class Program
{
static void Main(string[] args)
{
//定义观察目标对象
AllyControlCenter acc;
acc = new ConcreteAllyControlCenter("金庸群侠");
//定义四个观察者对象
IObserver player1, player2, player3, player4;
player1 = new Player("杨过");
acc.Join(player1);
player2 = new Player("令狐冲");
acc.Join(player2);
player3 = new Player("张无忌");
acc.Join(player3);
player4 = new Player("段誉");
acc.Join(player4);
//某成员遭受攻击
player1.BeAttacked(acc);
Console.Read();
}
}
}
8、 结果及分析，编译并运行程序，输出结果如下：
