JAVA设计模式2：工厂方法模式，将对象的实例化过程封装在子类

// 抽象产品类
interface Product {
    void operation();
}
// 具体产品类A
class ConcreteProductA implements Product {
    @Override
    public void operation() {
        System.out.println("ConcreteProductA operation");
    }
}
// 具体产品类B
class ConcreteProductB implements Product {
    @Override
    public void operation() {
        System.out.println("ConcreteProductB operation");
    }
}
// 简单工厂类
class SimpleFactory {
    public static Product createProduct(String type) {
        if (type.equals("A")) {
            return new ConcreteProductA();
        } else if (type.equals("B")) {
            return new ConcreteProductB();
        }
        return null;
    }
}
// 客户端使用
public class Client {
    public static void main(String[] args) {
        Product productA = SimpleFactory.createProduct("A");
        productA.operation();
        Product productB = SimpleFactory.createProduct("B");
        productB.operation();
    }
}

// 抽象产品类
interface Product {
    void operation();
}
// 具体产品类A
class ConcreteProductA implements Product {
    @Override
    public void operation() {
        System.out.println("ConcreteProductA operation");
    }
}
// 具体产品类B
class ConcreteProductB implements Product {
    @Override
    public void operation() {
        System.out.println("ConcreteProductB operation");
    }
}
// 抽象工厂类
interface Factory {
    Product createProduct();
}
// 具体工厂类A
class ConcreteFactoryA implements Factory {
    @Override
    public Product createProduct() {
        return new ConcreteProductA();
    }
}
// 具体工厂类B
class ConcreteFactoryB implements Factory {
    @Override
    public Product createProduct() {
        return new ConcreteProductB();
    }
}
// 客户端使用
public class Client {
    public static void main(String[] args) {
        Factory factoryA = new ConcreteFactoryA();
        Product productA = factoryA.createProduct();
        productA.operation();
        Factory factoryB = new ConcreteFactoryB();
        Product productB = factoryB.createProduct();
        productB.operation();
    }
}