java - 如何捕获 "NotesException: Notes error: Remote system no longer responding"并重试？

Question

我有这个 Java 代理程序，它可以处理大量文档，并且可以在一夜之间运行。问题是如果网络突然短暂断开，我需要代理重试。重试次数可能有上限。

int numberOfRetries = 0;
try {
    while(nextdoc != null) {
        // process documents
        numberOfRetries = 0;
    }
} catch (NotesException e) {
    numberOfRetries++;
    if (numberOfRetries > 4) {
        // go back and reprocess current document
    } else {
        // message reached max number of retries. did not successfully finished
    }
}

此外，我当然不想重试整个过程。基本上我需要继续处理它正在处理的文档并继续下一个循环

Answer 1

您应该围绕获取文档的每段代码执行重试循环。由于 Notes 类通常需要 getFirst 和 getNext 范例，这意味着您需要两个单独的重试循环。例如，

   numberOfRetries = 0;
   maxRetries = 4;   

   // get first document, with retries

   needToRetry = false;
   while (needToRetry)
   {
      try
      {
         while (needToRetry)
         {
            nextDoc = myView.getFirstDocument();
            needToRetry=false;
         }    
      }
      catch (NotesException e) 
      {
         numberOfRetries++;
         if (numberOfRetries < maxRetries) {
            // you might want to sleep here to wait for the network to recover
            // you could use numberOfRetries as a factor to sleep longer on
            // each failure
            needToRetry = true;
         } else {
            // write "Max retries have been exceeded getting first document" to log
            nextDoc = null; // we won't go into the processing loop 
         }
      }
   }

   // process all documents

   while(nextdoc != null) 
   {

      // process nextDoc
      //   insert your code here


      // now get next document, with retries

      while (needToRetry)
      {
         try
         {
            nextDoc = myView.getNextDocument();
            needToRetry=false;
         }  
         catch (NotesException e) 
         {
            numberOfRetries++;
            if (numberOfRetries < maxRetries) {
               // you might want to sleep here to wait for the network to recover
               // you could use numberOfRetries as a factor to sleep longer on
               // each failure
               needToRetry = true;
            } else {
               // write "Max retries have been exceeded getting first document" to log
               nextDoc = false; // we'lll be exiting the processing loop without finishing all docs 
            }
         }
      }
   }          

请注意，我将 maxRetries 视为数据集中所有文档的最大总重试次数，而不是每个文档的最大重试次数。

另请注意，将其分解一点可能更干净。例如

   numberOfRetries = 0;
   maxRetries = 4;  

   nextDoc = getFirstDocWithRetries(view);   // this contains while loop and try-catch

   while (nextDoc != null)
   { 
       processOneDoc(nextDoc);
       nextDoc = getNextDocWithRetries(view,nextDoc);   // and so does this
   }