建立不同的鸭子类 
fly行为
//  飞行接口 
public interface FlyBehavior {  
public void fly();  
}  
//  飞 
public class FlyWithWings implements FlyBehavior{  
public void fly() {  
        System.out.println("正在用翅膀飞行");  
    }  
}  
//  不飞 
public class FlyNoWay implements FlyBehavior{  
public void fly() {  
        System.out.println("不会飞");  
    }  
}  
//坐火箭飞 
public class FlyRocketPowered implements FlyBehavior{  
public void fly() {  
        System.out.println("坐火箭飞");  
    }  
}  
quack行为
//  叫接口 
public interface QuackBehavior {  
public void quack();  
}  
// 嘎嘎叫 
public class Quack implements QuackBehavior. {  
public void quack() {  
        System.out.println("嘎嘎叫");  
    }  
}  
//  吱吱叫 
public class Squeak implements QuackBehavior{  
public void quack() {  
        System.out.println("吱吱叫");  
    }  
}  
//  不叫 
public class MuteQuack implements QuackBehavior{  
public void quack() {  
        System.out.println("不会叫");  
    }  
} 
实现Duck类  
//  鸭子超类
public abstract class Duck {  
//  默认的行为 
FlyBehavior flyBehavior;  
    QuackBehavior quackBehavior;  

public Duck() {  
    }  
public void setFlyBehavior(FlyBehavior. fb) {  
        flyBehavior = fb;  
    }  
public void setQuackBehavior(QuackBehavior. qb) {  
        quackBehavior = qb;  
    }  
abstract void display();  
public void performFly() {  
        flyBehavior.fly();  
    }  
public void performQuack() {  
        quackBehavior.quack();  
    }  
public void swim() {  
        System.out.println("正在游泳~~");  
    }  
}  

//  野鸭  
     public class MallardDuck extends Duck {  
     public MallardDuck() {  
         quackBehavior = new Quack();  
                 flyBehavior = new FlyWithWings();  //这里也可以使用setFlyBehavior方法，下同！
     }  
     public void display() {  
         System.out.println("绿头鸭");  
     }  
}  
     //  红头鸭  
     public class RedHeadDuck extends Duck {  
     public RedHeadDuck() {  
         flyBehavior = new FlyWithWings();  
         quackBehavior = new Quack();  
     }  
     public void display() {  
         System.out.println("红头鸭");  
     }  
}  
     //  橡皮鸭  
    public class RubberDuck extends Duck {  
     public RubberDuck() {  
         flyBehavior = new FlyNoWay();  
         quackBehavior = new Squeak();  
     }  
     public void display() {  
         System.out.println("橡皮鸭");  
     }  
}  
     //模型鸭  
public class ModelDuck extends Duck {  
     public ModelDuck() {  
         flyBehavior = new FlyNoWay();  
         quackBehavior = new Quack();  
     }  
     public void display() {  
         System.out.println("模型鸭");  
     }  
}  

测试代码：

public class MiniDuckSimulator {  

public static void main(String[] args) {  

        MallardDuck    mallard = new MallardDuck();  
        RubberDuck    rubberDuckie = new RubberDuck();  
        RedHeadDuck    redHeadDuck = new RedHeadDuck();  

        ModelDuck    model = new ModelDuck();  

        mallard.performQuack();  
        rubberDuckie.performQuack();  
        redHeadDuck.performQuack();  

        model.performFly();      
        model.setFlyBehavior(new FlyRocketPowered());  
        model.performFly();  
    }  
}