概述
秒杀系统中总需要在启动时将数据放到redis中,即缓存预热,在秒杀开始时则需要通过redis进行库存的扣减,为保证redis和mysql数据一致性,通过可通过定时任务将redis中的数据同步回mysql中
demo
我们知道Redis数据的key通常以类名:midKey:商品id进行设计,为此我们根据key取出数据来,更新到数据库即可
@Component
public class RedisToMySqlScheduled implements ApplicationRunner {
@Autowired
private GoodsService goodsService;
@Autowired
private RedisUtil redisUtil;
//map用来做数据的缓存
private Map<Long,Boolean> map = new ConcurrentHashMap<>();
@Scheduled(cron = "15 05 11 * * ? ")
public void redisDataToMySql(){
if (!map.isEmpty()){
map.entrySet().forEach(entry->{
Integer count = redisUtil.get(GoodsKey.getSecondKillGoodsStock, ":" + entry.getKey(), Integer.class);
goodsService.redisToMysql(count,entry.getKey());
});
}
}
@Override
public void run(ApplicationArguments args) throws Exception {
//取出全部数据
List<GoodsVo> goodsVos = goodsService.listGoodsVo();
goodsVos.forEach(e->{
map.put(e.getId(),false);
});
}
}
service
public int redisToMysql(Integer count,Long goodId){
return goodsDao.redisDataToMysql(count,goodId);
}
mapper
@Update("update second_goods set stock_count = #{stockCount} where goods_id = #{goodsId}")
int redisDataToMysql(@Param("stockCount")Integer stockCount,@Param("goodsId")Long goodsId);