Factory Method -对象创建模型

    1.意图
            定义一个用于对象创建的接口，让子类决定实例化哪个类，Factory Method
            使一个类的实例化延迟到其子类。
    2.参与对象
            Product,ConcreteProduct,Creator,ConcreteCreator
    3.结构

      

代码：

public interface Creator {
   public Product getProduct(); 
}

public interface Product {
   void play();
}

public class ConcreteCreatorA implements Creator {
	private final static ConcreteCreatorA concreteCreatorA = new ConcreteCreatorA();
    private ConcreteCreatorA(){
    	
    }
	public static Creator getConcreteCreatorA(){
    	return concreteCreatorA;
    }
	@Override
	public Product getProduct() {
		return new ConcreteProductA();
	}

}

public class ConcreteCreatorB implements Creator {
	private final static ConcreteCreatorB concreteCreatorB = new ConcreteCreatorB();
    private ConcreteCreatorB(){
    	
    }
	public static Creator getConcreteCreatorB(){
    	return concreteCreatorB;
    }
	@Override
	public Product getProduct() {
		return new ConcreteProductB();
	}

}

public class ConcreteProductA implements Product {

	@Override
	public void play() {
		System.out.println("A.play");
	}

}

public class ConcreteProductB implements Product {

	@Override
	public void play() {
		System.out.println("B.play");
		
	}

}

public class Client {
	public static void main(String[] args) {
         Creator creator = ConcreteCreatorB.getConcreteCreatorB();
         Product  product  =creator.getProduct();
         product.play();
	}
}