一個簡單的工廠模式(一個接口，多個實現，通過調用條件的不同，分別去調用符合的實現)

接口：Animal.java

package Factoryface;

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

}
實現類（舉例兩個）：Cat.java

package Model;

import Factoryface.Animal;

public class Cat implements Animal {
    @Override
    public void eat() {
        System.out.println("貓喜歡吃魚");
    }

    @Override
    public void sport() {
        System.out.println("貓很懶，不喜歡運動");
    }
}
Dog.java

package Model;

import Factoryface.Animal;

public class Dog implements Animal {
    @Override
    public void eat() {
        System.out.println("狗喜歡啃骨頭");
    }

    @Override
    public void sport() {
        System.out.println("狗喜歡運動，喜歡玩球");
    }
}
簡單工廠：Factory1.java

package Model;

import Factoryface.Animal;

public class Factory1 {
    //定義兩個常量，負責與調用者交互
    public static final String CAT="cat";
    public static final String Dog="dog";
    //根據調用者傳來的描述，來返回調用者所需要的實現(str就是調用者傳來的參數)
    public Animal getAnimal(String str){
        if (CAT.equals(str)){
            return new Cat();
        }else if(Dog.equals(str)){
            return new Dog();
        }else{
            return null;
        }
    }
}
模擬調用者：FactoryTest.java

package Test;

import Factoryface.Animal;
import Model.Factory1;

//模擬調用者調用條件符合"dog"類
public class FactoryTest {
    public static void main(String[] args){
        Factory1 factory1 = new Factory1();
        Animal animal = null;
        animal = factory1.getAnimal("dog");
        animal.eat();
        animal.sport();
    }
}
輸出：