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");
     }

 }