引子
把大象装进冰箱需要3步：打开冰箱门，把大象装入冰箱，关闭冰箱门。
扩展一下，我们考虑把动物装进冰箱的场景。比如，把猪🐷装进冰箱，把狗🐶装进冰箱，等等。
怎么利用面向对象的思想来进行程序设计呢？
talk is cheap, show me the code.
把大象装进冰箱的程序设计及实现
把大象装进冰箱，这个比较简单，简单到只有某些初级程序员写不出来。
如下，估计都是这个玩法。
代码就不贴了。
把动物装进冰箱的程序设计及实现
推而广之，要把不同的动物装进冰箱，并且假定每种动物装进冰箱的方式不同。那么，该怎么进行程序设计来实现这个需求呢？
程序结构图
类结构图
model-模型类
Animal是抽象类（你可以new一头大象，一条狗，但你总不能new一个动物吧）：
package com.animal2icebox.model;
import lombok.Data;
@Data
public abstract class Animal {
String name;
}
大象模型类-Elephant：
package com.animal2icebox.model;
import lombok.Data;
@Data
public class Elephant extends Animal {
int weight;
}
狗狗模型类-Dog：
package com.animal2icebox.model;
import lombok.Data;
@Data
public class Dog extends Animal {
/**
* 狗狗品种
*/
String breed;
}
重点是把动物装进冰箱的服务类
AnimalIntoIceboxService是抽象基类，提供了把动物装进冰箱的门面方法。但是由于每一种动物装入冰箱的方式各不相同，所以，要暴露接口（抽象方法）给派生类来实现。
package com.animal2icebox.service;
import com.animal2icebox.model.Animal;
public abstract class AnimalIntoIceboxService {
IceboxService iceboxService=new IceboxService();
public void putIntoIcebox(Animal animal) {
System.out.println("=============================");
iceboxService.openTheDoor();
input(animal);
iceboxService.closeTheDoor();
}
protected abstract void input(Animal animal);
}
把大象装进冰箱-ElephantIntoIceboxService：
package com.animal2icebox.service;
import com.animal2icebox.model.Animal;
import com.animal2icebox.model.Elephant;
public class ElephantIntoIceboxService extends AnimalIntoIceboxService {
@Override
protected void input(Animal animal) {
Elephant elephant = (Elephant) animal;
System.out.println(String.format("大象信息：name=%s，重量=%s吨", elephant.getName(), elephant.getWeight()));
int threshold = 5;
int i = 0;
for (i = threshold; i <= elephant.getWeight(); i += threshold) {
System.out.println(String.format("这头大象重%s吨，已放入%s吨", elephant.getWeight(), threshold));
}
i -= threshold;
if (elephant.getWeight() > i) {
System.out.println(String.format("这头大象重%s吨，已放入%s吨", elephant.getWeight(), elephant.getWeight() - i));
}
System.out.println("已成功把大象装进冰箱！");
}
}
View Code
把狗狗装进冰箱-DogIntoIceboxService：
package com.animal2icebox.service;
import com.animal2icebox.model.Animal;
import com.animal2icebox.model.Dog;
public class DogIntoIceboxService extends AnimalIntoIceboxService {
@Override
protected void input(Animal animal) {
System.out.println("撒狗粮 here");
Dog dog=(Dog)animal;
String words = String.format("%s(品种=%s)", dog.getName(), dog.getBreed());
System.out.println("Hi " + words + ", welcome into the icebox...");
}
}
View Code
AnimalIntoIceboxFactory-工厂-生产的产品是上面的装进冰箱的动物service类对象
package com.animal2icebox.factory;
import com.animal2icebox.model.Animal;
import com.animal2icebox.model.Dog;
import com.animal2icebox.model.Elephant;
import com.animal2icebox.service.AnimalIntoIceboxService;
import com.animal2icebox.service.DogIntoIceboxService;
import com.animal2icebox.service.ElephantIntoIceboxService;
import lombok.Getter;
public class AnimalIntoIceboxFactory {
public static AnimalIntoIceboxService getServiceInstance(Animal animal) {
Class<AnimalIntoIceboxService> serviceClass = AnimalIntoBoxEnum.getServiceClass(animal);
assert serviceClass != null;
try {
return serviceClass.newInstance();
} catch (InstantiationException | IllegalAccessException e) {
e.printStackTrace();
}
return null;
}
@Getter
enum AnimalIntoBoxEnum {
Elephants(Elephant.class, ElephantIntoIceboxService.class),
Dogs(Dog.class, DogIntoIceboxService.class),
;
Class<Animal> animalClass;
Class<AnimalIntoIceboxService> serviceClass;
<E extends Animal, S extends AnimalIntoIceboxService> AnimalIntoBoxEnum(Class<E> animalClass, Class<S> serviceType) {
this.animalClass = (Class<Animal>) animalClass;
this.serviceClass = (Class<AnimalIntoIceboxService>) serviceType;
}
public static Class<AnimalIntoIceboxService> getServiceClass(Animal animal) {
AnimalIntoBoxEnum[] values = AnimalIntoBoxEnum.values();
for (AnimalIntoBoxEnum anEnum : values) {
if (anEnum.animalClass.equals(animal.getClass())) {
return anEnum.getServiceClass();
}
}
return null;
}
}
}
AnimalIntoIceboxContext-上下文容器，供外部调用
package com.animal2icebox.context;
import com.animal2icebox.factory.AnimalIntoIceboxFactory;
import com.animal2icebox.model.Animal;
import com.animal2icebox.model.Dog;
import com.animal2icebox.model.Elephant;
import com.animal2icebox.service.AnimalIntoIceboxService;
import java.util.ArrayList;
import java.util.List;
public class AnimalIntoIceboxContext {
public void putAnimalIntoIcebox(List<Animal> animals) {
for (Animal animal : animals) {
AnimalIntoIceboxService elephantIntoIceboxService = AnimalIntoIceboxFactory.getServiceInstance(animal);
assert elephantIntoIceboxService != null;
elephantIntoIceboxService.putIntoIcebox(animal);
}
}
}
来吧，开启调用之旅
package com.animal2icebox;
import com.animal2icebox.context.AnimalIntoIceboxContext;
import com.animal2icebox.model.Animal;
import com.animal2icebox.model.Dog;
import com.animal2icebox.model.Elephant;
import java.util.ArrayList;
import java.util.List;
public class AnimalIntoIceboxTest {
public static void main(String[] args) {
List<Animal> animals = new ArrayList<>();
Elephant elephant1 = new Elephant();
elephant1.setName("Emily");
elephant1.setWeight(13);
animals.add(elephant1);
Dog dog = new Dog();
dog.setName("Lucky");
dog.setBreed("dhole");
animals.add(dog);
Elephant elephant2 = new Elephant();
elephant2.setName("包包大人");
elephant2.setWeight(2);
animals.add(elephant2);
AnimalIntoIceboxContext context=new AnimalIntoIceboxContext();
context.putAnimalIntoIcebox(animals);
}
}
程序运行结果：
=============================
the door is open.
大象信息：name=Emily，重量=13吨
这头大象重13吨，已放入5吨
这头大象重13吨，已放入5吨
这头大象重13吨，已放入3吨
已成功把大象装进冰箱！
the door is closed.
=============================
the door is open.
撒狗粮 here
Hi Lucky(品种=dhole), welcome into the icebox...
the door is closed.
=============================
the door is open.
大象信息：name=包包大人，重量=2吨
这头大象重2吨，已放入2吨
已成功把大象装进冰箱！
the door is closed.
so，本文在“把动物装进冰箱”这个需求场景里，使用了哪些设计模式或设计思想呢？
