Java编程Retry重试机制实例详解

public void commonRetry(Map<String, Object> dataMap) throws InterruptedException { 
    Map<String, Object> paramMap = Maps.newHashMap(); 
    paramMap.put("tableName", "creativeTable"); 
    paramMap.put("ds", "20160220"); 
    paramMap.put("dataMap", dataMap); 
    boolean result = false; 
    try { 
      result = uploadToOdps(paramMap); 
      if (!result) { 
        Thread.sleep(1000); 
        uploadToOdps(paramMap); //一次重试 
      } 
    } catch (Exception e) { 
      Thread.sleep(1000); 
      uploadToOdps(paramMap);//一次重试 
    } 
  } 

public void commonRetry(Map<String, Object> dataMap) throws InterruptedException { 
    Map<String, Object> paramMap = Maps.newHashMap(); 
    paramMap.put("tableName", "creativeTable"); 
    paramMap.put("ds", "20160220"); 
    paramMap.put("dataMap", dataMap); 
    boolean result = false; 
    try { 
      result = uploadToOdps(paramMap); 
      if (!result) { 
        reuploadToOdps(paramMap,1000L,10);//延迟多次重试 
      } 
    } catch (Exception e) { 
      reuploadToOdps(paramMap,1000L,10);//延迟多次重试 
    } 
  } 

public void upload(final Map<String, Object> map) throws Exception { 
    // 构建重试模板实例 
    RetryTemplate retryTemplate = new RetryTemplate(); 
    // 设置重试策略，主要设置重试次数 
    SimpleRetryPolicy policy = new SimpleRetryPolicy(3, Collections.<Class<? extends Throwable>, Boolean> singletonMap(Exception.class, true)); 
    // 设置重试回退操作策略，主要设置重试间隔时间 
    FixedBackOffPolicy fixedBackOffPolicy = new FixedBackOffPolicy(); 
    fixedBackOffPolicy.setBackOffPeriod(100); 
    retryTemplate.setRetryPolicy(policy); 
    retryTemplate.setBackOffPolicy(fixedBackOffPolicy); 
    // 通过RetryCallback 重试回调实例包装正常逻辑逻辑，第一次执行和重试执行执行的都是这段逻辑 
    final RetryCallback<Object, Exception> retryCallback = new RetryCallback<Object, Exception>() { 
      //RetryContext 重试操作上下文约定，统一spring-try包装  
      public Object doWithRetry(RetryContext context) throws Exception { 
        System.out.println("do some thing"); 
        Exception e = uploadToOdps(map); 
        System.out.println(context.getRetryCount()); 
        throw e;//这个点特别注意，重试的根源通过Exception返回 
      } 
    }; 
    // 通过RecoveryCallback 重试流程正常结束或者达到重试上限后的退出恢复操作实例 
    final RecoveryCallback<Object> recoveryCallback = new RecoveryCallback<Object>() { 
      public Object recover(RetryContext context) throws Exception { 
        System.out.println("do recory operation"); 
        return null; 
      } 
    }; 
    try { 
      // 由retryTemplate 执行execute方法开始逻辑执行 
      retryTemplate.execute(retryCallback, recoveryCallback); 
    } catch (Exception e) { 
      e.printStackTrace(); 
    } 
  } 

public void uploadOdps(final Map<String, Object> map) { 
    // RetryerBuilder 构建重试实例 retryer,可以设置重试源且可以支持多个重试源，可以配置重试次数或重试超时时间，以及可以配置等待时间间隔 
    Retryer<Boolean> retryer = RetryerBuilder.<Boolean> newBuilder() 
        .retryIfException().//设置异常重试源 
        retryIfResult(new Predicate<Boolean>() {//设置自定义段元重试源， 
      @Override 
      public boolean apply(Boolean state) {//特别注意：这个apply返回true说明需要重试，与操作逻辑的语义要区分 
        return true; 
      } 
    }) 
    .withStopStrategy(StopStrategies.stopAfterAttempt(5))//设置重试5次，同样可以设置重试超时时间 
    .withWaitStrategy(WaitStrategies.fixedWait(100L, TimeUnit.MILLISECONDS)).build();//设置每次重试间隔 
 
    try { 
      //重试入口采用call方法，用的是java.util.concurrent.Callable<V>的call方法,所以执行是线程安全的 
      boolean result = retryer.call(new Callable<Boolean>() {  
        @Override 
        public Boolean call() throws Exception { 
          try { 
            //特别注意：返回false说明无需重试，返回true说明需要继续重试 
            return uploadToOdps(map); 
          } catch (Exception e) { 
            throw new Exception(e); 
          } 
        } 
      }); 
 
    } catch (ExecutionException e) { 
    } catch (RetryException ex) { 
    } 
  }