Spring-retry基本使用.docx

背景介紹在實(shí)際工作過程中，重試是一個(gè)經(jīng)常使用的手段。比如MQ發(fā)送消息失敗，會(huì)采取重試手段，比如工程中使用RPC請求外部服務(wù),可能因?yàn)榫W(wǎng)絡(luò)波動(dòng)出現(xiàn)超時(shí)而采取重試手段.可以看見重試操作是非常常見的一種處理問題,系統(tǒng)設(shè)計(jì)的手段而在之前我們項(xiàng)目中處理重拾操作依賴MQ自身的重試機(jī)制,但是這種機(jī)制不是很靈活,如果某些功能沒有使用MQ的話,那么就不是那么方便了,而本文介紹的Spring-Retry卻能夠以一種很優(yōu)雅的方式解決這種問題,當(dāng)然目前版本的Spring-retry還不是完美的,還是有待改進(jìn)的.不過已經(jīng)很不錯(cuò)了.基本使用例子1ConfigurationEnableRetrypublic class Application Bean public Service service() return new Service(); Serviceclass Service Retryable(RemoteAccessException.class) public void service() / . do something Recover public void recover(RemoteAccessException e) / . panic 例子2org.springframework.stereotype.Servicepublic class Service1 Retryable(value = RemoteAccessException.class, RuntimeException.class, maxAttempts = 2, backoff = Backoff(value = 2000) public void service() System.out.println(do some things); / this exception will just trigger recover1, do not trigger recover3 throw new RemoteAccessException(remote access exception); / this exception will just trigger recover2/ throw new RuntimeException(runtime exception);/ System.out.println(do another things); / 如果使用注解的話,這個(gè)recover貌似只能寫在本類中,我測試了如果將recover方法寫在 / recoverService中,好像找不到 Recover public void recover1(RemoteAccessException e) System.out.println(e.getMessage(); System.out.println(do recover operation1); Recover public void recover2(RuntimeException e) System.out.println(e.getMessage(); System.out.println(do recover operation2); Recover public void recover3(RemoteAccessException e) System.out.println(e.getMessage(); System.out.println(do recover operation3); 例子3Servicepublic class Service2 public void test() final RetryTemplate retryTemplate = new RetryTemplate(); final SimpleRetryPolicy policy = new SimpleRetryPolicy(3, Collections.Class, Boolean singletonMap(Exception.class, true); FixedBackOffPolicy fixedBackOffPolicy = new FixedBackOffPolicy(); fixedBackOffPolicy.setBackOffPeriod(100); retryTemplate.setRetryPolicy(policy); retryTemplate.setBackOffPolicy(fixedBackOffPolicy); final RetryCallback retryCallback = new RetryCallback() public Object doWithRetry(RetryContext context) throws Exception System.out.println(do some thing); /設(shè)置context一些屬性,給RecoveryCallback傳遞一些屬性 context.setAttribute(key1, value1); System.out.println(context.getRetryCount(); throw new Exception(exception);/ return null; ; / 如果RetryCallback執(zhí)行出現(xiàn)指定異常, 并且超過最大重試次數(shù)依舊出現(xiàn)指定異常的話,就執(zhí)行RecoveryCallback動(dòng)作 final RecoveryCallback recoveryCallback = new RecoveryCallback() public Object recover(RetryContext context) throws Exception System.out.println(do recory operation); System.out.println(context.getAttribute(key1); return