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Spring retry基本使用

2015-08-07 17:27  Rollen Holt  阅读(20539)  评论(0编辑  收藏  举报

Spring retry基本使用

背景介绍

在实际工作过程中,重试是一个经常使用的手段。比如MQ发送消息失败,会采取重试手段,比如工程中使用RPC请求外部服务,可能因为网络
波动出现超时而采取重试手段......可以看见重试操作是非常常见的一种处理问题,系统设计的手段

而在之前我们项目中处理重拾操作依赖MQ自身的重试机制,但是这种机制不是很灵活,如果某些功能没有使用MQ的话,那么就不是那么方便了,而本文介绍的
Spring-Retry却能够以一种很优雅的方式解决这种问题,当然目前版本的Spring-retry还不是完美的,还是有待改进的.不过已经很不错了.

基本使用

  • 例子1

      @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2

     @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");
         }
     
         // 如果使用注解的话,这个recover貌似只能写在本类中,我测试了如果将recover方法写在
         // 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3

     @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");
                     //设置context一些属性,给RecoveryCallback传递一些属性
                     context.setAttribute("key1", "value1");
                     System.out.println(context.getRetryCount());
                     throw new Exception("exception");
     //                return null;
                 }
             };
     
             // 如果RetryCallback执行出现指定异常, 并且超过最大重试次数依旧出现指定异常的话,就执行RecoveryCallback动作
             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();
             }
         }
     }
    

参考资料