guava的重试机制guava-retrying使用

1，添加maven依赖

<dependency>
      <groupId>com.github.rholder</groupId>
      <artifactId>guava-retrying</artifactId>
      <version>2.0.0</version>
    </dependency>

2，定义重试机制

Retryer<CMSResultDTO> smsRetryer = RetryerBuilder.<CMSResultDTO>newBuilder()      
.retryIfResult(cmsResultDTO->cmsResultDTO.getCode() != SM_SUCCESS_CODE)  // 短信返回的码不是200要重试
.retryIfResult(Predicates.<CMSResultDTO>isNull())            // 返回的数据是null要重试
.retryIfExceptionOfType(Exception.class)                    // 返回的异常错误类
.withStopStrategy(StopStrategies.stopAfterAttempt(ATTEMPT_NUM))
.withWaitStrategy(WaitStrategies.fixedWait(SLEEP_TIME, TimeUnit.SECONDS))    // 隔1秒重试
.withRetryListener(new SMRetryListener<>())
.build();

3，定义要重试的任务

 Callable<CMSResultDTO> task = ()->{
            log.info("sm input param:type=>{}, interCode=>{}, mobile=>{}, pair=>{}",
                    type, interCode, mobile, pair);
            CMSResultDTO cmsResultDTO = cmsService.sendMessage(type, interCode, mobile, pair);
            log.info("sm return data:{}", JSON.toJSONString(cmsResultDTO));
            return cmsResultDTO;
        };

4，重试机制重试任务

CMSResultDTO cmsResultDTO = null;
        try {
            cmsResultDTO = smsRetryer.call(task);
        } catch (ExecutionException e) {
            log.error("SM ExecutionException", e);
        } catch (RetryException e) {
            log.error("SM RetryException", e);
        }
        return cmsResultDTO;

以下是一个关于重试发短信的完整例子

/**
     * 重试机制 发送短信接口支持国际码
     * @param type 模版号
     * @param interCode 国际码
     * @param mobile 手机号码
     * @param pair 参数对
     * @return 消息发送结果，包括发送状态和消息标识
     */
    public CMSResultDTO retrySendMessage(Integer type, String interCode, String mobile, Map<String, String> pair) throws CMSQueueException, CMSSendException {
        Preconditions.checkNotNull(type, "type不能为null");
        Preconditions.checkNotNull(interCode, "interCode不能为null");
        Preconditions.checkNotNull(mobile, "mobile不能为null");
        Preconditions.checkNotNull(pair, "pair不能为null");

        Callable<CMSResultDTO> task = ()->{
            log.info("sm input param:type=>{}, interCode=>{}, mobile=>{}, pair=>{}",
                    type, interCode, mobile, pair);
             //调用第三方发短信接口，得到返回值，第一时间记录到log中
            CMSResultDTO cmsResultDTO = cmsService.sendMessage(type, interCode, mobile, pair);
            log.info("sm return data:{}", JSON.toJSONString(cmsResultDTO));
            return cmsResultDTO;
        };
        //定义重试的机制原理
        Retryer<CMSResultDTO> smsRetryer = RetryerBuilder.<CMSResultDTO>newBuilder()
                .retryIfResult(cmsResultDTO->cmsResultDTO.getCode() != SM_SUCCESS_CODE)  // 短信返回的码不是200要重试
                .retryIfResult(Predicates.<CMSResultDTO>isNull())            // 返回的数据是null要重试
                .retryIfExceptionOfType(Exception.class)                    // 返回的异常错误类
                .withStopStrategy(StopStrategies.stopAfterAttempt(ATTEMPT_NUM))
                .withWaitStrategy(WaitStrategies.fixedWait(SLEEP_TIME, TimeUnit.SECONDS))    // 隔1秒重试
                //监听器
                .withRetryListener(new SMRetryListener<>())
                .build();
        
        CMSResultDTO cmsResultDTO = null;
        try {
        //执行任务的重试，得到返回结果
            cmsResultDTO = smsRetryer.call(task);
        } catch (ExecutionException e) {
            log.error("SM ExecutionException", e);
        } catch (RetryException e) {
            log.error("SM RetryException", e);
        }
        return cmsResultDTO;
    }
    
    //自定义的监听器
    /**
     * 重试监听器
     * @param <CMSResultDTO>
     */
    private class SMRetryListener<CMSResultDTO> implements RetryListener {

        @Override
        public <CMSResultDTO> void onRetry(Attempt<CMSResultDTO> attempt) {
            log.info("[retry]time=" + attempt.getAttemptNumber());
            if (attempt.hasException()) {
                log.error("retry exception", attempt.getExceptionCause());
            }
            if (attempt.hasResult()) {
                if (attempt.getResult() == null) {
                    log.info("retry return data is null");
                } else {
                    log.info("retry return data is:{}", JSON.toJSONString(attempt.getResult()));
                }
            }
        }
        
    }