AOP 结合 guava retryer 实现接口自动重试

心已赠人 2021-11-27 02:56 255阅读 1赞

# 概述 #

Guava Retryer 类，及可以用来方便的创建 Retryer 的强大工具类 RetryerBuilder

本篇日志中，我们通过面向切面结合 guava 的这个强大的工具类，来实现只需要添加一行注解即可的自动重试机制

# 注解 #

我们的注解旨在通过简单的参数配置常用的重试策略：

@Target(ElementType.METHOD)
    
    @Retention(RetentionPolicy.RUNTIME)
    
    public @interface TechlogRetryer {
    
    long waitMsec() default 0;
    
    Class[] retryThrowable() default {};
    
    long maxDelayMsec() default 0;
    
    int maxAttempt() default 0;
    
    }

# 切面 #

我们以上面的注解为切点构造一个切面，实现对方法的自动处理

@Around(value = "@annotation(TechlogRetryer)")
    
    public Object monitorAround(ProceedingJoinPoint pjp) throws
    
            Throwable {
    
    Method method;
    
    if (pjp.getSignature() instanceof MethodSignature) {
    
    MethodSignature signature = (MethodSignature) pjp
    
                    .getSignature();
    
    method = signature.getMethod();
    
    } else {
    
    LOGGER.error("Monitor Annotation not at a method {}", pjp);
    
    return null;
    
    }
    
    TechlogRetryer retryerAnnotation = method.getDeclaredAnnotation
    
                (TechlogRetryer.class);
    
    if (retryerAnnotation.maxDelayMsec() <= 0 && retryerAnnotation
    
                .maxAttempt() <= 1) {
    
    return pjp.proceed();
    
    }
    
    RetryerBuilder retryer = RetryerBuilder.newBuilder();
    
    if (retryerAnnotation.waitMsec() > 0) {
    
    retryer.withWaitStrategy(fixedWait(retryerAnnotation
    
                    .waitMsec(), TimeUnit.MILLISECONDS));
    
    }
    
    if (retryerAnnotation.retryThrowable().length > 0) {
    
    for (Class retryThrowable : retryerAnnotation
    
                    .retryThrowable()) {
    
    if (retryThrowable != null && Throwable.class
    
                        .isAssignableFrom(retryThrowable)) {
    
    retryer.retryIfExceptionOfType(retryThrowable);
    
    }
    
    }
    
    }
    
    if (retryerAnnotation.maxDelayMsec() > 0) {
    
    retryer.withStopStrategy(StopStrategies.stopAfterDelay
    
                    (retryerAnnotation.maxDelayMsec(), TimeUnit
    
                    .MILLISECONDS));
    
    }
    
    if (retryerAnnotation.maxAttempt() > 0) {
    
    retryer.withStopStrategy(StopStrategies.stopAfterAttempt
    
                    (retryerAnnotation.maxAttempt()));
    
    }
    
    String retrylog = pjp.getTarget().getClass().getCanonicalName()
    
                + "." + method.getName();
    
    return retryer.build().call(() -> {
    
    try {
    
    LOGGER.info("<TECHLOG_RETRYER>" + retrylog);
    
    return pjp.proceed();
    
    } catch (Throwable throwable) {
    
    if (throwable instanceof Exception) {
    
    throw (Exception) throwable;
    
    } else {
    
    throw new Exception(throwable);
    
    }
    
    }
    
    });
    
    }
    
    }

# 使用实例 #

对于我们希望进行重试的方法，我们只需要加上注解并配置合适的参数即可

@TechlogRetryer(retryThrowable = NeedCatchException.class, maxAttempt =
    
        2)
    
    public Map<Long, SpuQuery> getPoiSpuListByIds(Long poiId, List<Long>
    
        poiSpuIds) {
    
    try {
    
    SpuListResponse skuListResponse = productService.getSpuByIds
    
                (poiId, poiSpuIds);
    
    if(skuListResponse == null || skuListResponse.getData() == null
    
                || skuListResponse.getData().isEmpty()) {
    
    return null;
    
    }
    
    Map<Long, SpuQuery> result = new HashMap<>();
    
    for (SpuQuery spuQuery : skuListResponse.getData()) {
    
    result.put(spuQuery.getSpuId(), spuQuery);
    
    }
    
    return result;
    
    } catch (TException e) {
    
    throw new NeedCatchException(e, null);
    
    }
    
    }