基于 AOP 和 Redis 实现的分布式锁

野性酷女 2022-06-16 09:07 131阅读 0赞

思路是：

*  获取锁使用 redis setnx key value 特性 ：如果设置成功，返回 1 。 设置失败，返回 0 。
 *  设置key 的过期时间
 *  用完了删除key
 *  采用 AOP 提高开发效率
 *  自定义注解 包含 过期时间，等待时间，key

自定义注解

/**
     * Created by linving on 2017/4/24.
     */
    @Target({ ElementType.METHOD})
    @Retention(RetentionPolicy.RUNTIME)
    public @interface RedisLock {
        
        //等待时间
        int maxWait() default 0;
        //过期时间
        int expiredTime() default 0;
        // key
        String[] keys() default {};
    }

AOP实现

/**
     * Created by linving on 2017/4/21.
     * TODO
     * 加鎖 采用注解
     */
    @Component
    @Aspect
    public class CashLockInterceptor {
        
        public static Logger logger = LoggerFactory.getLogger(CashLockInterceptor.class);
    
        @Autowired 
        RedisOperator redisOperator;
    
        /**
         * 切面 加有 RedisLock 的 service 方法
         */
        @Pointcut("execution(* com.xx.service..*.*(..)) && @annotation(com.xx.annotation.RedisLock)")
        private void cutMethod() {
        }
    
        @Before("cutMethod()")
        public void doAccessCheck(JoinPoint point) throws NoSuchMethodException {
            logger.info("Before...");
        }
    
        @AfterReturning("cutMethod()")
        public void doAfter(JoinPoint point) {
            logger.info("AfterReturning...");
        }
    
        @After("cutMethod()")
        public void after(JoinPoint point) {
            logger.info("After...");
        }
    
        @AfterThrowing("cutMethod()")
        public void doAfterThrow() {
            logger.info("AfterThrowing...");
        }
    
        @Around("cutMethod()")
        public Object doBasicProfiling(ProceedingJoinPoint pjp) throws Throwable {
            String methodName = pjp.getSignature().getName();
            Class<?> classTarget = pjp.getTarget().getClass();
            Class<?>[] par = ((MethodSignature) pjp.getSignature()).getParameterTypes();
            Method objMethod = classTarget.getMethod(methodName, par);
            RedisLock redisLock = objMethod.getDeclaredAnnotation(RedisLock.class);
            String[] keys = redisLock.keys();
            int maxWait = redisLock.maxWait();
            int expiredTime = redisLock.expiredTime();
    
            Object result = null;
            try {
    
                logger.info("前置通知");
                //获取锁
                Arrays.stream(keys).forEach(key -> {
                    boolean flag = redisOperator.tryGetRedisLock(key, "", maxWait, expiredTime);
                    if(!flag){
                  //获取失败抛异常
                        throw new APIBusinessException(ErrorCodeEnum.CODE_SYSTEM_GET_MUCH);
                    }
                });
                //代理执行
                result = pjp.proceed();
                logger.info("后置通知");
            } catch (Throwable e) {
                 //释放锁
                Arrays.stream(keys).forEach(key->{
                    redisOperator.releaseLock(key,"");
                });
                logger.info("异常通知");
                throw e;
            }
            logger.info("返回通知");
            //释放锁
            Arrays.stream(keys).forEach(key->{
                redisOperator.releaseLock(key,"");
            });
            return result;
        }
    
    }

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