定義

定義一個(gè)用于創(chuàng)建對象的接口,讓子類決定實(shí)例化那個(gè)類

UML類圖

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解讀:

• Product: 產(chǎn)品抽象類,
• ConcreteProduct: 產(chǎn)品實(shí)現(xiàn)類
• Creator: 工廠抽象類, 返回一個(gè)Product實(shí)例
• ConcreteCreator: 工廠實(shí)現(xiàn)類, 返回一個(gè)ConcreteProduct實(shí)例

簡單實(shí)現(xiàn)

Fruit: 作為產(chǎn)品抽象類

public abstract class Fruit {
    abstract void getName();
}

Banana: 作為產(chǎn)品實(shí)現(xiàn)類

public class Banana extends Fruit {
    @Override
    void getName() {
        System.out.println("I am banana");
    }
}

Apple: 作為產(chǎn)品實(shí)現(xiàn)類

public class Apple extends Fruit {
    @Override
    void getName() {
        System.out.println("I am apple");
    }
}

FruitFactory: 作為抽象工廠類

public abstract class FruitFactory  {
    abstract Fruit createFruit();
}

AppleFactory: 作為工廠實(shí)現(xiàn)類

public class AppleFactory extends FruitFactory {
    @Override
    Fruit createFruit() {
        return new Apple();
    }
}

BananaFactory: 作為工廠實(shí)現(xiàn)類

public class BananaFactory extends FruitFactory {
    @Override
    Fruit createFruit() {
        return new Banana();
    }
}

使用

在需要哪一個(gè)產(chǎn)品時(shí)就生產(chǎn)哪個(gè)

FruitFactory fruitFactory = new AppleFactory();
Fruit apple = fruitFactory.createFruit();
apple.getName();

使用反射

FruitFactory

public abstract class FruitFactory  {
    abstract <T extends Fruit> T createFruit(Class<T> className);
}

ConcreteFruitFactory: 具體工廠類

public class ConcreteFruitFactory extends FruitFactory {
    @Override
    <T extends Fruit> T createFruit(Class<T> className) {
        Fruit fruit = null;
        try {
            fruit = (Fruit)Class.forName(className.getName()).newInstance();
        }catch (Exception e){
            e.printStackTrace();
        }
        return (T)fruit;
    }
}

使用

需要哪個(gè)類對象就傳入那個(gè)類的類型

       FruitFactory fruitFactory = new ConcreteFruitFactory();
       Fruit apple = fruitFactory.createFruit(Apple.class);
       apple.getName();

簡單工廠方法模式

當(dāng)工廠只有一個(gè)的時(shí)候, 只需將對應(yīng)的工廠方法改為靜態(tài)方法, 并去掉abstract關(guān)鍵字, 此時(shí)就變成了簡單工廠模式或者靜態(tài)工廠模式

public class FruitFactory  {
    static Fruit createFruit(){
        return new Apple();
    }
}