Spring Boot + Redission实战 -＞ 实现分布式锁

需求场景：执行推送任务，保证每个任务只推送一次。
处理流程：将需要幂等性的接口加上自定义注解。然后编写一个切面，在Around方法里逻辑：尝试获取分布式锁(带过期时间)，成功表明没重复提交，否则就是重复提交了。
具体的redis已经配置在了nacos中，这里不做赘述。

1.添加Redission依赖

<dependency>
        <groupId>org.redissongroupId>
        <artifactId>redisson-spring-boot-starterartifactId>
        <version>3.11.5version>
dependency>

2.自定义注解类型实现分布式锁：@Lock

@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Component
public @interface Lock {

    String prefix() default "";

    String key() default "";

    long expire() default 60L;

    int tryCount() default 3;
} 

3.分布式锁切面：LockAspect

@Slf4j
@Aspect
@Order(1000)
@Component
public class LockAspect {
    public static final String TASK_PUSH_LOCK_PREFIX = "cms:";
	
    @Autowired
    private RedissonClient redissonClient;
    private static DefaultParameterNameDiscoverer discoverer = new DefaultParameterNameDiscoverer();
    private static SpelExpressionParser parser = new SpelExpressionParser();

    //增强带有Lock注解的方法
    @Pointcut("@annotation(com.xxx.cms.service.annotation.Lock)")
    public void LockAspect() {
    }

    @Around("LockAspect()")
    public Object redisLock(ProceedingJoinPoint point) throws Throwable {
        Object result;
        Class<?> clazz = point.getTarget().getClass();
        MethodSignature methodSignature = (MethodSignature) point.getSignature();
        Method method = clazz.getDeclaredMethod(methodSignature.getName(), methodSignature.getParameterTypes());
        Lock redisLockAnnotation = method.getAnnotation(Lock.class);
		// 拼接 key
        final String key = generateKeyBySpEL(redisLockAnnotation.key(), method, point.getArgs());
       
	    String prefix = StringUtils.isEmpty(redisLockAnnotation.prefix()) ? TASK_PUSH_LOCK_PREFIX + ":"+ method.getName()+":" : redisLockAnnotation.prefix();
        String lockKey = StringUtils.isEmpty(key)
                ? prefix
                : prefix + ":" + key;
        log.info("分布式锁,创建key:{}", lockKey);
        //redisson核心步骤1 getLock 获取锁
		final RLock lock = redissonClient.getLock(lockKey);
		
        try {
            lockKeyList.add(new RedisLockInfo(lockKey, redisLockAnnotation.expire(), redisLockAnnotation.tryCount(), Thread.currentThread()));
            //redisson核心步骤2 lock  加锁
     	    lock.lock(redisLockAnnotation.expire(), TimeUnit.SECONDS);
     	    //需要加锁的具体业务逻辑
            result = point.proceed();
			//redisson核心步骤3 unlock 释放锁
            lock.unlock();
            log.info("# [END]分布式锁,删除key:{}", lockKey);
            return result;
        } catch (CommonException ie) {
            log.error("分布式锁,请求超时", ie.getMessage());
            throw new Exception(ie.getMessage());
        } catch (Exception e) {
            log.error("分布式锁,创建失败", e);
			//redisson核心步骤4 unlock 最后记得释放锁
            lock.unlock();
            log.info("# [END]分布式锁,删除key:{}", lockKey);
        }
        return false;
    }

    private static String generateKeyBySpEL(String spELString, Method method, Object[] args) {
        String[] paramNames = discoverer.getParameterNames(method);
        Expression expression = parser.parseExpression(spELString);
        EvaluationContext context = new StandardEvaluationContext();
        for (int i = 0; i < args.length; i++) {
            assert paramNames != null;
            context.setVariable(paramNames[i], args[i]);
        }
        return Objects.requireNonNull(expression.getValue(context)).toString();
    }

    @Data
    class RedisLockInfo{
        private String key;
        private int tryNums;
        private int tryCount;
        private Thread thread;
        private long expireTime;

        public RedisLockInfo(String key,long expireTime,int tryCount,Thread thread){
            this.key = key;
            this.tryCount = tryCount;
            this.thread = thread;
            this.expireTime = expireTime;
        }
    }
}	

4.任务推送执行器TaskPushExecutor

@Component("taskPushExecutor")
public class TaskPushExecutor extends AbstractExecutor<UserInfo> {
    public static final String PUSH_TASK_PREFIX = "cms:push:task:scheduler:";
    //只需要在保证幂等性的接口上，加上自定义的@Lock注解就好了
	@Lock(prefix=PUSH_TASK_PREFIX,key="#task.taskSign+':'+#task.taskId+':'+#task.userGroupId",expire = 300L,tryCount = 3)
    @Override
    public void execute(ITaskHandler taskHandler, Task task) {
        //执行具体的业务逻辑
        executeTask(taskHandler, task);
    }
}

5.查询执行日志状况

可以通过Kibana查看日志，发现加锁和释放锁，均是成对出现，分布式锁正常！

参考文章
拜托，面试请不要再问我Redis分布式锁的实现原理
Spring Boot + Redis实战-利用自定义注解+分布式锁实现接口幂等性