MVC和观察者模式

用观察者模式实现MVC框架！

http://wenku.baidu.com/view/eff8bab069dc5022aaea0007.html

写的不错！

Observer和ConcreteObserver，观察者

public interface Observer
{
    public abstract void update(NumberGenerator generator);
}
public class DigitObserver implements Observer 
{
    public void update(NumberGenerator generator) 
    {
        System.out.println("DigitObserver:" + generator.getNumber());
        try 
        {
            Thread.sleep(100);
        } 
        catch (InterruptedException e) 
        {
        }    
    }
}

public class GraphObserver implements Observer 
{
    public void update(NumberGenerator generator) 
    {
        System.out.print("GraphObserver:");
        int count = generator.getNumber();
        for (int i = 0; i < count; i++) 
        {
            System.out.print("*");
        }
        System.out.println("");
        try 
        {
            Thread.sleep(100);
        } 
        catch (InterruptedException e) 
        {
        }   
    }
}

  Subject、ConcreteSubject被观察者

import java.util.Vector;
import java.util.Iterator;

public abstract class NumberGenerator 
{
    private Vector observers = new Vector();        // 储存Observer 
    public void addObserver(Observer observer) 
    {    // 新增Observer
        observers.add(observer);
    }
    public void deleteObserver(Observer observer) 
    { // 刪除Observer
        observers.remove(observer);
    }
    public void notifyObservers() 
    {               // 通知Observer
        Iterator it = observers.iterator();
        while (it.hasNext()) 
        {
            Observer o = (Observer)it.next();
            o.update(this);
        }
    }
    public abstract int getNumber();                // 取得数值
    public abstract void execute();                 // 产生数值
}
import java.util.Random;

public class RandomNumberGenerator extends NumberGenerator 
{
    private Random random = new Random();   // 随机数生成器
    private int number;                     // 目前数值
    public int getNumber() 
    {                // 取得数值
        return number;
    }
    public void execute() 
    {
        for (int i = 0; i < 20; i++) 
        {
            number = random.nextInt(50);
            notifyObservers();
        }
    }
}

调用：

public class Main 
{
    public static void main(String[] args) 
    {
        NumberGenerator generator = new RandomNumberGenerator();
        Observer observer1 = new DigitObserver();
        Observer observer2 = new GraphObserver();
        generator.addObserver(observer1);
        generator.addObserver(observer2);
        generator.execute();
    }
}

将观察者Observer添加给被观察者Subject，被观察者Subject更新观察者Observer的状态。

以上是观察者模式。