【文件属性】：
文件名称：缓存穿透.txt
文件大小：860B
文件格式：TXT
更新时间：2022-09-12 03:38:21
高并发技术
@Service("userServiceImpl")
public class UserServiceImpl implements UserService {
@Autowired
private UserMapper userMapper;
@Autowired
private RedisTemplate<Object,Object> redisTemplate;
@Override
public Long queryAllUserCount() {
Long allUserCount= (Long) redisTemplate.opsForValue().get(Constants.ALL_USER_COUNT);
if(allUserCount==null){
//注意缓存穿透
synchronized (this){
allUserCount= (Long) redisTemplate.opsForValue().get(Constants.ALL_USER_COUNT);
if(allUserCount==null){
allUserCount=userMapper.selectAllUserCount();
redisTemplate.opsForValue().set(Constants.ALL_USER_COUNT, allUserCount, 15, TimeUnit.SECONDS);
}
}
}
return allUserCount;
}
}