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。

巴特西

MVC和观察者模式

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