《HeadFirst设计模式(第二版)》第一章源码

代码文件目录结构：

 

FlyBehavior.java

package Chapter1_StrategyPattern.ch1_3_behavior.behaviors.fly;

public interface FlyBehavior {
    void fly();
}

FlyNoWay.java

package Chapter1_StrategyPattern.ch1_3_behavior.behaviors.fly;

public class FlyNoWay implements FlyBehavior{
    @Override
    public void fly() {
        System.out.println("I can't fly!");
    }
}

FlyRocketPowered.java

package Chapter1_StrategyPattern.ch1_3_behavior.behaviors.fly;

public class FlyRocketPowered implements FlyBehavior{
    @Override
    public void fly() {
        System.out.println("I'm flying with a rocket!");
    }
}

FlyWithWings.java

package Chapter1_StrategyPattern.ch1_3_behavior.behaviors.fly;

public class FlyWithWings implements FlyBehavior{
    public void fly(){
        System.out.println("I'm flying!");
    }
}

QuackBehavior.java

package Chapter1_StrategyPattern.ch1_3_behavior.behaviors.quack;

public interface QuackBehavior {
    public void quack();
}

MuteQuack.java

package Chapter1_StrategyPattern.ch1_3_behavior.behaviors.quack;

public class MuteQuack implements QuackBehavior{
    @Override
    public void quack() {
        System.out.println("<< Silence >>");
    }
}

Quack.java

package Chapter1_StrategyPattern.ch1_3_behavior.behaviors.quack;

public class Quack implements QuackBehavior{
    @Override
    public void quack() {
        System.out.println("Quack!");
    }
}

Squeak.java

package Chapter1_StrategyPattern.ch1_3_behavior.behaviors.quack;

public class Squeak implements QuackBehavior{
    @Override
    public void quack() {
        System.out.println("Squeak!");
    }
}

Duck.java

package Chapter1_StrategyPattern.ch1_3_behavior;

import Chapter1_StrategyPattern.ch1_3_behavior.behaviors.fly.FlyBehavior;
import Chapter1_StrategyPattern.ch1_3_behavior.behaviors.quack.QuackBehavior;

public abstract class Duck {
    FlyBehavior flyBehavior;
    QuackBehavior quackBehavior;

    public Duck(){}

    public void setFlyBehavior(FlyBehavior flyBehavior) {
        this.flyBehavior = flyBehavior;
    }

    public void setQuackBehavior(QuackBehavior quackBehavior) {
        this.quackBehavior = quackBehavior;
    }

    public void performFly(){
        this.flyBehavior.fly();
    }

    public void performQuack(){
        this.quackBehavior.quack();
    }

    public void swim(){
        System.out.println("the duck is swimming!");
    }

    public abstract void display();
}

MallardDuck.java

package Chapter1_StrategyPattern.ch1_3_behavior;

import Chapter1_StrategyPattern.ch1_3_behavior.behaviors.fly.FlyWithWings;
import Chapter1_StrategyPattern.ch1_3_behavior.behaviors.quack.Quack;

//绿头鸭
public class MallardDuck extends Duck {

    public MallardDuck(){
        this.flyBehavior = new FlyWithWings();
        this.quackBehavior = new Quack();
    }

    @Override
    public void display() {
        System.out.println("this is a MallardDuck!");
    }
}

RedHeadDuck.java

package Chapter1_StrategyPattern.ch1_3_behavior;

import Chapter1_StrategyPattern.ch1_3_behavior.behaviors.fly.FlyWithWings;
import Chapter1_StrategyPattern.ch1_3_behavior.behaviors.quack.Quack;

public class RedHeadDuck extends Duck {

    public RedHeadDuck(){
        this.flyBehavior = new FlyWithWings();
        this.quackBehavior = new Quack();
    }

    @Override
    public void display() {
        System.out.println("this is a redHeadDuck!");
    }
}

RubberDuck.java

package Chapter1_StrategyPattern.ch1_3_behavior;

import Chapter1_StrategyPattern.ch1_3_behavior.behaviors.fly.FlyNoWay;
import Chapter1_StrategyPattern.ch1_3_behavior.behaviors.quack.Squeak;

public class RubberDuck extends Duck{

    public RubberDuck(){
        this.flyBehavior = new FlyNoWay();
        this.quackBehavior = new Squeak();
    }

    @Override
    public void display() {
        System.out.println("this is a rubberDuck!");
    }
}

DecoyDuck.java

package Chapter1_StrategyPattern.ch1_3_behavior;

import Chapter1_StrategyPattern.ch1_3_behavior.behaviors.fly.FlyNoWay;
import Chapter1_StrategyPattern.ch1_3_behavior.behaviors.quack.MuteQuack;

public class DecoyDuck extends Duck {

    public DecoyDuck(){
        this.flyBehavior = new FlyNoWay();
        this.quackBehavior = new MuteQuack();
    }

    @Override
    public void display() {
        System.out.println("this is a DecoyDuck!");
    }
}

ModelDuck.java

package Chapter1_StrategyPattern.ch1_3_behavior;

import Chapter1_StrategyPattern.ch1_3_behavior.behaviors.fly.FlyNoWay;
import Chapter1_StrategyPattern.ch1_3_behavior.behaviors.quack.MuteQuack;

public class ModelDuck extends Duck{

    public ModelDuck(){
        this.quackBehavior = new MuteQuack();
        this.flyBehavior = new FlyNoWay();
    }
    @Override
    public void display() {
        System.out.println("I'm a model duck!");
    }
}

MiniDuckSimulator.java

package Chapter1_StrategyPattern.ch1_3_behavior;

import Chapter1_StrategyPattern.ch1_3_behavior.behaviors.fly.FlyRocketPowered;

public class MiniDuckSimulator {
    public static void main(String[] args) {
        Duck mallard = new MallardDuck();
        mallard.performFly();
        mallard.performQuack();

        Duck model = new ModelDuck();
        model.performFly();
        model.setFlyBehavior(new FlyRocketPowered());
        model.performFly();
    }
}

notes.txt

ch1_1

直接使用继承来应付新增子类的问题

问题：
1.当子类鸭子的数量越来越多的时候，继承就难以保证整个系统的可维护性，因为每次添加一个子类，
  都要对对应的属性是否要实现进行考虑
2.代码在多个子类重复
3.代码在运行时难以改变

ch1_2

将其中某些非共通的行为抽取出来作为接口

问题：
1.对于具有同一个行为的每个子类都会重复代码，可维护性差

ch1_3

1.将某一类行为抽取出来作为一系列行为类，从is-a转为has-a ==> 将继承转成组合
2.使用setter实现动态设置行为


设计模式：
    定义一个算法族，分别封装起来，是的他们之间可以相互变换，使得算法的变化独立于使用他的客户（鸭子）

运行结果：