抽奖系统简单实现

表模型设计

• 营销活动表
• 抽奖规则表
  • 类型 如下单抽奖，大促抽奖，积分抽奖
• 奖品表
• 中奖记录表
• 抽奖资格表
• 条件商品表

ISSUSES

• 抽奖权限
  • 人的白黑名单控制
  • 控制渠道
• 中奖概率控制
• 并发控制
  • 对抽中的奖品加锁
• 抽奖后的履约方式
  • 线下履约
  • 加入购物车
  • 直接生成奖品0元订单

具体实现案例

• 权限判断【设计模式：责任链】

//定义需要执行的chain
@Data  
public class LotteryPrivilegeChain {  
  
    private List<LotteryPrivilegeHandler> handlers = Lists.newArrayList();  
  
    public boolean process(LotteryPrivilegeContext context) {  
        for (LotteryPrivilegeHandler handler : handlers) {  
            boolean flag = handler.handle(context);  
            if (!flag) {  
                return false;  
            }  
        }  
        return true;  
    }  
  
    public void addHandlers(List<LotteryPrivilegeHandler> handlers) {  
        this.handlers = handlers;  
    }  
  
    public void addHandler(LotteryPrivilegeHandler handler) {  
        this.getHandlers().add(handler);  
    }  
  
}

//定义handler接口，有具体的权限判断需要实现这个接口
@FunctionalInterface  
public  interface LotteryPrivilegeHandler {  
    boolean handle(LotteryPrivilegeContext context);  
}

//context类，存放后续需要判断的一些字段
@Getter  
@Setter  
public class LotteryPrivilegeContext {  
    private Integer userId;
    private Integer channel;

}


//引入所有实现的handlers
@Autowired  
private List<LotteryPrivilegeHandler> lotteryPrivilegeHandlers;

//具体调用逻辑
LotteryPrivilegeChain chain = new LotteryPrivilegeChain();  
chain.addHandlers(lotteryPrivilegeHandlers);

LotteryPrivilegeContext lotteryPrivilegeContext = LotteryPrivilegeContext.create()  
        .withUserId(userId)  
        .withChannel(request.getChannel());  
boolean flag = chain.process(lotteryPrivilegeContext);


//判断flag 执行后续的具体逻辑

• 抽奖履约实现【设计模式：责任链】

//handler 定义


@FunctionalInterface  
public interface LotteryAcceptService {  
    LotteryAcceptContext accept(LotteryAcceptContext context);  
}


//默认实现，后续也可继续封装抽象类提供模板方法
@Slf4j  
@Component  
public class DefaultLotteryAcceptServiceImpl implements LotteryAcceptService {  
  
    @Autowired  
    private List<LotteryShipHandler> lotteryShipHandlers;  
  
    @Override  
    @Transactional(rollbackFor = Throwable.class)  
    public LotteryAcceptContext accept(LotteryAcceptContext context) {  
        check(context);  
        //前置处理,如数据填充
        beforeHandler(context);  
        //具体实现
        process(context);  
        //后置处理，如更新数据库
        afterHandler(context);  
        return context;  
    }

void process(LotteryAcceptContext context) {  
    LotteryShipChain chain = new LotteryShipChain();  
    chain.addHandlers(lotteryShipHandlers);  
    boolean flag = chain.process(context);  
    context.setSuccess(flag);  
    if (!flag) {  
        context.setFailCode(context.getFailCode());  
        context.setFailMap(context.getFailMap());  
    }  
}