工厂模式

//工厂模式，创建对象的静态方法叫做工厂方法，比如spring的bean工厂

public class AUDI extends Car{
}

public class BENZ extends Car{
}

public class BMW extends Car{
}

public class NISSAN extends Car{
}

public enum CarType {
    NISSAN,
    AUDI,
    BENZ,
    BMW
}

public static Car generateCar(CarType carType){
    Car car = null;
    switch (carType){
        case NISSAN:
            car =new NISSAN();
            break;
        case BMW:
            car =new BMW();
            break;
        case BENZ:
            car =new BENZ();
            break;
        case AUDI:
            car =new AUDI();
            break;
    }
    return car;

}