//关键点1
@Component
public class Demo { 
    //关键点2
    private static RedisUtils redisUtils;
    @Autowired
    private RedisUtils redis;
    //关键点3
    @PostConstruct
    public void init() {
        //关键点4
        //等价写法：Demo. redisUtils = this.redis; 
        redisUtils = this.redis;
    }
    public static String foo() {
        String accessToken = redisUtils.get(RedisKeys.getAccessTokenKey());
        return accessToken;
    }
}