一个简单的工厂模式(一个接口，多个实现，通过调用条件的不同，分别去调用符合的实现)

接口：Animal.java

package Factoryface;

public interface Animal {
    public void eat();
    public void sport();

}
实现类（举例两个）：Cat.java

package Model;

import Factoryface.Animal;

public class Cat implements Animal {
    @Override
    public void eat() {
        System.out.println("猫喜欢吃鱼");
    }

    @Override
    public void sport() {
        System.out.println("猫很懒，不喜欢运动");
    }
}
Dog.java

package Model;

import Factoryface.Animal;

public class Dog implements Animal {
    @Override
    public void eat() {
        System.out.println("狗喜欢啃骨头");
    }

    @Override
    public void sport() {
        System.out.println("狗喜欢运动，喜欢玩球");
    }
}
简单工厂：Factory1.java

package Model;

import Factoryface.Animal;

public class Factory1 {
    //定义两个常量，负责与调用者交互
    public static final String CAT="cat";
    public static final String Dog="dog";
    //根据调用者传来的描述，来返回调用者所需要的实现(str就是调用者传来的参数)
    public Animal getAnimal(String str){
        if (CAT.equals(str)){
            return new Cat();
        }else if(Dog.equals(str)){
            return new Dog();
        }else{
            return null;
        }
    }
}
模拟调用者：FactoryTest.java

package Test;

import Factoryface.Animal;
import Model.Factory1;

//模拟调用者调用条件符合"dog"类
public class FactoryTest {
    public static void main(String[] args){
        Factory1 factory1 = new Factory1();
        Animal animal = null;
        animal = factory1.getAnimal("dog");
        animal.eat();
        animal.sport();
    }
}
输出：