重試邏輯uptil數據庫出現

Question

通過我的java代碼我連接到多個數據庫使用連接pooling.if我的數據庫下降我需要處理重試邏輯來獲取連接，直到它返回一個連接對象。

Answer 1

如果你的數據庫連接拋出某種異常，那麼你可以睡一會兒再重試該操作。

在下面的工人的例子是一個對象，做了一些工作，如連接到數據庫，等等。這是非常通用的，所以您可以重試任何類型的操作，例如從文件中讀取等

請注意，捕獲Throwable可能不一定是個好主意。

boolean success = false; 
    int i = 0; 
    long delay = retryDelay; 

    LOGGER.info("Starting operation"); 

    /* 
    * Loop until you cannot retry anymore or the operation completed successfully 
    * The catch block has a nested try catch to ensure that nothing goes wrong 
    * while trying to sleep 
    * 
    * In case of failure the last retry exception is propagated up to the calling 
    * class. 
    */ 
    while (i++ < retryMax && !success) 
    { 
     try 
     { 
      worker.work(); 
      success = true; 
     } 
     catch (Throwable t) 
     { 
      try 
      { 
       LOGGER.warn("Caught throwable", t); 

       if (i == retryMax) 
       { 
        LOGGER.warn("Retry maximum reached, propagating error"); 
        throw t; 
       } 

       if (retryPolicy == RetryPolicy.ESCALATING) 
       { 
        delay *= 2; 
       } 

       LOGGER.info("Sleeping for " + delay + " milliseconds"); 

       Thread.sleep(delay); 
      } 
      catch (Throwable tt) 
      { 
       /* 
       * Quick check to see if the maximum has been hit, so we don't log twice 
       * 
       * t is the original error, and tt is the error we got while retrying 
       * tt would most likely be a InterruptedException or something 
       */ 
       if (i == retryMax) 
       { 
        throw t; 
       } 

       LOGGER.warn("Error while retrying, propagating original error up", tt); 

       throw t; 
      } 
     } 

    } // end retry loop