Spring retry基本使用

時間 2019-11-05

原文原文鏈接

Spring retry基本使用

背景介紹

在實際工做過程當中，重試是一個常常使用的手段。好比MQ發送消息失敗，會採起重試手段，好比工程中使用RPC請求外部服務,可能由於網絡
波動出現超時而採起重試手段......能夠看見重試操做是很是常見的一種處理問題,系統設計的手段html

而在以前咱們項目中處理重拾操做依賴MQ自身的重試機制,可是這種機制不是很靈活,若是某些功能沒有使用MQ的話,那麼就不是那麼方便了,而本文介紹的
Spring-Retry卻可以以一種很優雅的方式解決這種問題,固然目前版本的Spring-retry還不是完美的,仍是有待改進的.不過已經很不錯了.java

基本使用

例子1git

@Configuration
  @EnableRetry
  public class Application {

      @Bean
      public Service service() {
          return new Service();
      }

  }

  @Service
  class Service {
      @Retryable(RemoteAccessException.class)
      public void service() {
          // ... do something
      }
      @Recover
      public void recover(RemoteAccessException e) {
         // ... panic
      }
  }

例子2github

@org.springframework.stereotype.Service
 public 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");
     }

     // 若是使用註解的話,這個recover貌似只能寫在本類中,我測試了若是將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3spring

@Service
 public class Service2 {

     public void test(){
         final RetryTemplate retryTemplate = new RetryTemplate();
         final SimpleRetryPolicy policy = new SimpleRetryPolicy(3, Collections.<Class<? extends Throwable>, Boolean>
                 singletonMap(Exception.class, true));
         FixedBackOffPolicy fixedBackOffPolicy = new FixedBackOffPolicy();
         fixedBackOffPolicy.setBackOffPeriod(100);
         retryTemplate.setRetryPolicy(policy);
         retryTemplate.setBackOffPolicy(fixedBackOffPolicy);
         final RetryCallback<Object, Exception> retryCallback = new RetryCallback<Object, Exception>() {
             public Object doWithRetry(RetryContext context) throws Exception {
                 System.out.println("do some thing");
                 //設置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;
             }
         };

         // 若是RetryCallback執行出現指定異常, 而且超過最大重試次數依舊出現指定異常的話,就執行RecoveryCallback動做
         final RecoveryCallback<Object> recoveryCallback = new RecoveryCallback<Object>() {
             public Object recover(RetryContext context) throws Exception {
                 System.out.println("do recory operation");
                 System.out.println(context.getAttribute("key1"));
                 return null;
             }
         };

         try {
             final Object execute = retryTemplate.execute(retryCallback, recoveryCallback);
         } catch (Exception e) {
             e.printStackTrace();
         }
     }
 }