示例类图

外观模式.png

示例代码

public class PointsGift {
    private String name;
    public PointsGift(String name) {
        this.name = name;
    }
    public String getName() {
        return name;
    }    
}

public class QualifyService {
    public boolean isAvailable(PointsGift pointsGift){
        System.out.println("校验" + pointsGift.getName() + " 积分资格通过,库存通过");
        return true;
    }
}

public class PointsPaymentService {
    public boolean pay(PointsGift pointsGift){
        //扣减积分
        System.out.println("支付" + pointsGift.getName() + " 积分成功");
        return true;
    }
}

public class ShippingService {
    public String shipGift(PointsGift pointsGift){
        //物流系统的对接逻辑
        System.out.println(pointsGift.getName() + "进入物流系统");
        String shippingOrderNo = "666";
        return shippingOrderNo;
    }
}

public class GiftExchangeService {

    private QualifyService qualifyService = new QualifyService();
    private PointsPaymentService pointsPaymentService = new PointsPaymentService();
    private ShippingService shippingService = new ShippingService();

    public void giftExchange(PointsGift pointsGift){
        if(qualifyService.isAvailable(pointsGift)){
            //资格校验通过
            if(pointsPaymentService.pay(pointsGift)){
                //如果支付积分成功
                String shippingOrderNo = shippingService.shipGift(pointsGift);
                System.out.println("物流系统下单成功,订单号是:"+shippingOrderNo);
            }
        }
    }

}

public class Test {
    public static void main(String[] args) {
        PointsGift pointsGift = new PointsGift("T恤");
        GiftExchangeService giftExchangeService = new GiftExchangeService();
        giftExchangeService.giftExchange(pointsGift);
    }
}

输出：

校验T恤 积分资格通过,库存通过
支付T恤 积分成功
T恤进入物流系统
物流系统下单成功,订单号是:666