java接口应用—策略设计模式

     策略模式：定义了一系列算法，将每一种算法封装起来并可以相互替换使用，策略模式让算法独立于使用它的客户应用而独立变化

       strategy pattern：The Strategy Pattern defines a family of algorithms,encapsulates each one,and makes them interchangeable. Strategy lets the algorithm vary independently from clients that use it.

oo设计原则：

1、面向接口编程（面向抽象编程）

2、封装变化

3、多用组合，少用继承

例子：

package practice1;

public class Test9 {

    public static void main(String[] args) {
          Duck duck=new BlackDuck("黑鸭子", new FlyImpl());
          duck.fly();
          
          Duck duck2=new ModeDuck("白鸭子", new NotFlyImpl());
          duck2.fly();
    }
}
class Duck{
    private String name;
    private Flyable flyable;//把接口作为属性
        
    public Duck(String name,Flyable flyable){
        this.name=name;
        this.flyable=flyable;
    }
    public void fly(){
        flyable.fly();
    }
}

class BlackDuck extends Duck{

    public BlackDuck(String name, Flyable flyable) {
        super(name, flyable);
    }
    
}
class ModeDuck extends Duck{

    public ModeDuck(String name, Flyable flyable) {
        super(name, flyable);
    }

}
//接口
interface Flyable{
    public void fly();
}

class FlyImpl implements Flyable{

    @Override
    public void fly() {
       System.out.println("会飞");    
    }
    
}

class NotFlyImpl implements Flyable{

    @Override
    public void fly() {
        System.out.println("不会飞");
    }
    
}