让我看看谁还写if/switch

原创于 2023-04-06 00:00:19 发布 · 163 阅读

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利用多态代替if switch优化代码

最近在读一本叫做《重构：改善既有代码的设计》的书，觉得很不错。书中有一个令我印象深刻的优化方式是利用多态代替判断。正好我在公司中也在开发类似代码，于是就想写个demo测试一下。如果可行，准备去优化公司现有代码

代码实现

整体架构

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具体代码

优化之前

Animal 类

import java.io.Serializable;

/**
 * @Author: Yuyan_i
 * @Title: Animal
 * @Date: 2023-04-05 22:40
 * @Description: 动物类
 */
public class Animal implements Serializable {
    private String type;

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }
}

BeforeMain main文件

import java.io.Serializable;

/**
 * @Author: Yuyan_i
 * @Title: BeforeMain
 * @Date: 2023-04-05 22:44
 * @Description:
 */
public class BeforeMain {
    public static void main(String[] args) {
        Animal animal = new Animal();
        animal.setType("cat");
        if ("fish".equals(animal.getType())){
            System.out.println("游");
        }else if ("cat".equals(animal.getType())){
            System.out.println("跑");
        }else {
            System.out.println("出错了");
        }
    }
}

优化之后

OperateChooser类

import com.mydemo.after.domain.Animal;
import com.mydemo.after.domain.animalimpl.Cat;
import com.mydemo.after.domain.animalimpl.Fish;
import com.mydemo.after.operate.AnimalOperate;

/**
 * @Author: Yuyan_i
 * @Title: AnimalChooser
 * @Date: 2023-04-05 21:18
 * @Description: 操作选择器
 */
public class OperateChooser {
    public static AnimalOperate chooseAnimalOperate(Animal animal){
        switch (animal.getType()){
            case "cat":
                return new Cat();
            case "fish":
                return new Fish();
            default:
                return null;
        }
    }
}

Animal 抽象类

import com.mydemo.after.operate.AnimalOperate;

import java.io.Serializable;

/**
 * @Author: Yuyan_i
 * @Title: Animal
 * @Date: 2023-04-05 21:12
 * @Description: 动物 超类
 */
public abstract class Animal implements Serializable, AnimalOperate {
    String type;
    public String getType(){
        return this.type;
    }
}

Cat 猫–子类

import com.mydemo.after.domain.Animal;

import java.io.Serializable;

/**
 * @Author: Yuyan_i
 * @Title: Cat
 * @Date: 2023-04-05 21:15
 * @Description: 猫
 */
public class Cat extends Animal implements Serializable {
    private static String type = "cat";
    public String getType(){
        return this.type;
    }

    @Override
    public void run() {
        System.out.println("跑");
    }
}

Fish 鱼–子类

import com.mydemo.after.domain.Animal;

import java.io.Serializable;

/**
 * @Author: Yuyan_i
 * @Title: Fish
 * @Date: 2023-04-05 21:16
 * @Description: 鱼
 */
public class Fish extends Animal implements Serializable {
    private static String type = "fish";
    public String getType(){
        return this.type;
    }

    @Override
    public void run() {
        System.out.println("游");
    }
}

AnimalOperate 操作接口

/**
 * @Author: Yuyan_i
 * @Title: AnimalOperate
 * @Date: 2023-04-05 21:22
 * @Description: 操作接口
 */
public interface AnimalOperate {
    public void run();
}

PolymorphicTest main文件

import com.mydemo.after.chooser.OperateChooser;
import com.mydemo.after.domain.animalimpl.Cat;
import com.mydemo.after.domain.animalimpl.Fish;

/**
 * @Author: Yuyan_i
 * @Title: PolymorphicTest
 * @Date: 2023-04-05 21:34
 * @Description: main文件
 */
public class PolymorphicTest {
    public static void main(String[] args) {
        Fish fish = new Fish();
        OperateChooser.chooseAnimalOperate(fish).run();

        Cat cat = new Cat();
        OperateChooser.chooseAnimalOperate(cat).run();
    }
}