design_model（2）factory

1.简单工厂模式（用的最多）

优点没：没必要知道那么多接口的实现了，只需要知道工厂，生成的对象我们只需要知道知道接口

缺点：不修改代码无法拓展实现类，拓展性较差

public interface Car {
	
}

public class Audi  implements  Car {
	
}

public class Bwm  implements  Car {

}

//简单工厂:可拓展性差,每增加一个车型，都需要在这其中加入else  if
public class CarFactory {
    public  static  Car  createCar(String str) {
    	if(str=="audi") {
    		 return  new Audi();
    	}else if(str=="bwm") {
    		 return  new Bwm();
    	}
    	return null;
    }
}

public class Client {
	public static void main(String[] args) {
		System.out.println(CarFactory.createCar("audi"));
	}
}

 2.工厂方法模式

优点：较简单工厂可拓展性较好

缺点：较简单工厂需要知道的工厂较多，结构较简单工厂复杂，随着工厂类的增加，类越来越多

 

public interface Car {
	
}

public class Audi  implements  Car {
	
}

public class Bwm  implements  Car {

}

public interface  Factory {
	
}

public class AudiFactory  implements  Factory{
	
	public static Car createCar() {
		return  new  Audi();
	}

}

public class BwmFactory implements Factory {

	public static Car createCar() {
		return new Bwm();
	}

}

public class Client {
	public static void main(String[] args) {
		Car audi = AudiFactory.createCar();
	}
}

 3.抽象工厂模式

优点：用来生产不同产品族的全部产品；支持增加产品族

缺点：对于增加新的产品，无能为力；支持增加产品族

 

public interface Engine {

}

public class LowEngine implements  Engine{

}

public class LuxuryEngine implements  Engine{

}

public interface Factory {
	
}

public class LowFactory  implements  Factory{
	public static  Engine   createEngine() {
		return  new LowEngine();
	}
}

public class LuxuryFactory implements  Factory{
	public static  Engine   createEngine() {
		return  new LuxuryEngine();
	}
}