Using PHP Strategy Pattern

Question:

1. If we define a duck class, it has two methods: swimming and appearance.
2. When demand increases, we need to add methods for ducks to fly and quack.
3. Not all ducks can quack or fly. General ducks can, but plastic ducks cannot fly. The rubber duck cannot fly or quack.
4. When the needs change again, we add a new frog class, and the frog can cry.

etc. etc. When the requirements change, our code is difficult to handle. At this time we can consider the strategy pattern.

If you use the strategy pattern, then your code becomes flexible, the code is as follows

1. We create a flying interface

public interface Fly { public void flyBehavior(); }

2. Write what you need The class implements this interface

public class FlyNoWay implements Fly{ @Override public void flyBehavior() { System.out.println("不会飞"); } }

public class FlyWithWings implements Fly{ @Override public void flyBehavior() { System.out.println("用翅膀飞"); } }

3. Create a duck class

public abstract class Duck { //多态形式定义飞行 private Fly fly; //多态的形式定义叫声 private QuackBehavior quackBehavior; public void display(){ System.out.println("黄色的鸭子"); } public void swim(){ System.out.println("鸭子可以游泳"); } public void perforFly(){ fly.flyBehavior(); } public void perforQuack(){ quackBehavior.quack(); } public Fly getFly() { return fly; } public void setFly(Fly fly) { this.fly = fly; } public QuackBehavior getQuackBehavior() { return quackBehavior; } public void setQuackBehavior(QuackBehavior quackBehavior) { this.quackBehavior = quackBehavior; } }

4. The subclass inherits the parent class and makes the subclass have its own characteristics

public class RubberDuck extends Duck{ public RubberDuck(){ //在创造这个子类的时候就确定了它具体的飞行和叫声方法 setFly(new FlyNoWay()); setQuackBehavior(new MuteQuack()); } @Override public void display() { System.out.println("白色的橡皮鸭"); } }

5 .If we need to add a frog class at this time, there are also croaking sounds written in the same way, because using the strategy pattern makes your code more flexible.

6. Test class

public class TestMain { public static void main(String[] args) { KeDaDuck keDaDuck = new KeDaDuck(); keDaDuck.display(); keDaDuck.perforFly(); keDaDuck.perforQuack(); PlasticDuck plasticDuck = new PlasticDuck(); plasticDuck.display(); plasticDuck.perforFly(); plasticDuck.perforQuack(); RubberDuck rubberDuck = new RubberDuck(); rubberDuck.display(); rubberDuck.perforFly(); rubberDuck.perforQuack(); Rana rana = new Rana(); rana.perforQuack(); } }

Summary

1.多用组合，少用继承。 2.在项目开始前就策划好，让其代码变得有弹性，防止增加和改变需求。 3.把一样的放在本类里，把不一样的容易变的部分抽出去。最后在组合起来。

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