背景

最近在工作中，要处理分布式多组件间的通信反馈问题，但是因为没有学习过设计模式，导致了编码实现的功能健壮性很差，并且难以维护，自己都理不清整个流程的逻辑细节。

面对这种情况，开始学习《Head First 设计模式》这本书。并将学到的模型记录下来。接下来学第一个设计模式：

策略模式

设计原则汇总

1. 找出应用中可能需要变化之处，把他们独立出来，不要和那些不需要变化的代码混在一起。 2. 针对接口编程，而不是针对实现编程。 3. 多用组合，少用继承。

代码实现

1.Duck.java package lesson1; /** * Created by willard on 17/4/4. */ public abstract class Duck { FlyBehavior flyBehavior; QuackBehavior quackBehavior; public Duck() { } public abstract void display(); public void performFly() { flyBehavior.fly(); } public void performQuack() { quackBehavior.quack(); } public void swim() { System.out.println("All ducks float, even decoys!"); } public void setFlyBehavior(FlyBehavior flyBehavior) { this.flyBehavior = flyBehavior; } public void setQuackBehavior(QuackBehavior quackBehavior) { this.quackBehavior = quackBehavior; } } 2.FlyBehavior.java package lesson1; /** * Created by willard on 17/4/4. */ public interface FlyBehavior { public void fly(); } 3.FlyNoWings.java package lesson1; /** * Created by willard on 17/4/4. */ public class FlyNoWings implements FlyBehavior { @Override public void fly() { System.out.println("I can't fly."); } } 4.FlyRocketPowered.java package lesson1; /** * Created by willard on 17/4/4. */ public class FlyRocketPowered implements FlyBehavior { @Override public void fly() { System.out.println("I'm flying with a rocket!"); } } 5.FlyWithWings.java package lesson1; /** * Created by willard on 17/4/4. */ public class FlyWithWings implements FlyBehavior { @Override public void fly() { System.out.println("I'm flying!!"); } } 6.MallardDuck.java package lesson1; /** * Created by willard on 17/4/4. */ public class MallardDuck extends Duck { public MallardDuck() { quackBehavior = new Quack(); flyBehavior = new FlyWithWings(); } @Override public void display() { System.out.println("I'm a real Mallard duck"); } } 7.MiniDuckSimulator.java package lesson1; /** * Created by willard on 17/4/4. */ public class MiniDuckSimulator { public static void main(String[] args) { Duck mallard = new MallardDuck(); mallard.performQuack(); mallard.performFly(); Duck model = new ModelDuck(); model.performFly(); model.setFlyBehavior(new FlyRocketPowered()); model.performFly(); } } 8.ModelDuck.java package lesson1; /** * Created by willard on 17/4/4. */ public class ModelDuck extends Duck { public ModelDuck() { flyBehavior = new FlyNoWings(); quackBehavior = new Quack(); } @Override public void display() { System.out.println("I'm a model duck"); } } 9.MuteQuack.java package lesson1; /** * Created by willard on 17/4/4. */ public class MuteQuack implements QuackBehavior { @Override public void quack() { System.out.println("<< Silence >>"); } } 10.Quack.java package lesson1; /** * Created by willard on 17/4/4. */ public class Quack implements QuackBehavior { @Override public void quack() { System.out.println("Quack"); } } 11.QuackBehavior.java package lesson1; /** * Created by willard on 17/4/4. */ public interface QuackBehavior { public void quack(); } 12.Squeak.java package lesson1; /** * Created by willard on 17/4/4. */ public class Squeak implements QuackBehavior { @Override public void quack() { System.out.println("Squea"); } }

结构关系图

待补充......