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。