工厂设计模式

定义：定义了一个创建对象的接口，但由子类决定要实例化的类是哪一个。工厂方法让类把实例化推迟到子类。

举例说明：

car接口：

package factory;

public interface Car {

    String getCarName();

}

car实例1：

package factory;

public class AudiCar implements Car {

    @Override
    public String getCarName() {
        return "audi";
    }

}

car实例2：

package factory;

public class BmwCar implements Car {

    @Override
    public String getCarName() {
        return "bmw";
    }

}

CarFactory抽象类：

package factory;

public abstract class CarFactory {

    Car car;

    public void saleCar() {
        car = createCar();
        System.out.println("create car");
        sale(car);
    }

    abstract Car createCar();

    void sale(Car car) {
        System.out.println("sale " + car.getCarName());

    }

}

具体工厂1：

package factory;

public class AudiFactory extends CarFactory {

    @Override
    Car createCar() {
        return new AudiCar();
    }

}

具体工厂2：

package factory;

public class BmwFacory extends CarFactory {

    @Override
    Car createCar() {
        return new BmwCar();
    }

}

测试类：

package factory;

public class Test {

    public static void main(String[] args) {
        CarFactory carFactory = new BmwFacory();
        carFactory.saleCar();
        System.out.println("**********");
        carFactory = new AudiFactory();
        carFactory.saleCar();
    }

}

执行结果：

create car
sale bmw
**********
create car
sale audi