一. 定义

简单工厂其实并不是一个设计模式，说它是一种良好的编程规范更为合适。它将创建对象的代码和业务逻辑的代码相互隔离开来，增加了程序的松耦合效果。

二. 模式起源

三. 设计原则

封装变化。

四. UML图

五. 代码

5.1 水果类

package model.simpleFactory;

/**
 * 水果类
 */
public abstract class Fruit {

    /**
     * 展示是哪种水果
     */
    public abstract void show();

}

5.2 苹果水果类

package model.simpleFactory;

/**
 * 水果：苹果
 */
public class Apple extends Fruit {

    @Override
    public void show() {
        System.out.println("i am a apple");
    }
}

5.3 香蕉水果类

package model.simpleFactory;

/**
 * 水果: 香蕉
 */
public class Banana extends Fruit {

    @Override
    public void show() {
        System.out.println("I am a banana");
    }
}

5.4 橘子水果类

package model.simpleFactory;

/**
 * 水果： 橙子
 */
public class Orange extends Fruit {

    @Override
    public void show() {
        System.out.println("I am an orange");
    }
}

5.5 梨水果类

package model.simpleFactory;

/**
 * 水果： 梨
 */
public class Pear extends Fruit {

    @Override
    public void show() {
        System.out.println("I am a Pear");
    }
}

5.6 简单水果工厂类

package model.simpleFactory;

/**
 * 简单水果工厂
 */
public class SimpleFruitFactory {

    /**
     * 创建水果
     *
     * @param type 类型
     * @return Fruit
     */
    public static Fruit createFruit(String type) {

        Fruit fruit = null;

        if (type.equals("apple")) {
            fruit = new Apple();
        } else if (type.equals("banana")) {
            fruit = new Banana();
        } else if (type.equals("orange")) {
            fruit = new Orange();
        } else if (type.equals("pear")) {
            fruit = new Pear();
        }

        return fruit;
    }

}

5.7 水果商店类

package model.simpleFactory;

/**
 * 水果商店
 */
public class FruitStore {

    /**
     * 内部维护一个简单水果工厂
     */
    private SimpleFruitFactory factory;

    public FruitStore(SimpleFruitFactory factory) {
        this.factory = factory;
    }

    public Fruit orderFruit(String type) {

        Fruit fruit = SimpleFruitFactory.createFruit(type);

        fruit.show();

        return fruit;
    }


}

5.8 测试

package model.simpleFactory;

public class Main {

    public static void main(String[] args) {

        SimpleFruitFactory simpleFruitFactory = new SimpleFruitFactory();
        FruitStore fruitStore = new FruitStore(simpleFruitFactory);

        fruitStore.orderFruit("apple");

        fruitStore.orderFruit("banana");

    }

}