正確使用log4j和異常

Question

我對將Log4j與Exceptions配合使用有疑問。 我想將消息記錄到我的日志文件中，但我不知道如何處理異常。 我只需要使用例外（因為已經在我的日志文件中打印了）或一些其他東西：

try {
        Configurations.getInstance().getProperty("DynamoDBProfileCredentials");
        credentials = new ProfileCredentialsProvider( Configurations.getInstance().getProperty("DynamoDBProfileCredentials")).getCredentials();

    } catch (Exception e) {
        log.error(new AmazonClientException("Cannot load the credentials from the credential profiles file. " +
                "Please make sure that your credentials file is at the correct " +
                "location (C:\\Users\\your username\\credentials), and is in valid format.",e));

或這個

try {
        Configurations.getInstance().getProperty("DynamoDBProfileCredentials");
        credentials = new ProfileCredentialsProvider( Configurations.getInstance().getProperty("DynamoDBProfileCredentials")).getCredentials();

    } catch (Exception e) {
        log.error("Cannot load the credentials from the credential profiles file. " +
                "Please make sure that your credentials file is at the correct " +
                "location (C:\\Users\\your username\\credentials), and is in valid format.",e);
        throw new AmazonClientException(
                "Cannot load the credentials from the credential profiles file. " +
                        "Please make sure that your credentials file is at the correct " +
                        "location (C:\\Users\\your username\\credentials), and is in valid format.",
                        e);

提前致謝。

Answer 1

異常只是信號/事件； 在您的應用程序范圍內發生。 記錄這些是另一個主題。

我了解您需要在應用程序中記錄有用的消息。 在您的情況下，您可以在方法的使用者上觸發日志事件，也可以直接在執行時觸發日志事件。

最簡單的情況是：

try {
  Configurations.getInstance().getProperty("DynamoDBProfileCredentials");
  credentials = new ProfileCredentialsProvider( Configurations.getInstance().getProperty("DynamoDBProfileCredentials")).getCredentials(); 
} catch (Exception e) {
  AmazonClientException ace = AmazonClientException(
      "Cannot load the credentials from the credential profiles file. " +
      "Please make sure that your credentials file is at the correct " +
      "location (C:\\Users\\your username\\credentials), and is in valid format.", e);

  log.error(ace.getMessage(), ace);
  throw ace;
}

要么

try {
  Configurations.getInstance().getProperty("DynamoDBProfileCredentials");
  credentials = new ProfileCredentialsProvider( Configurations.getInstance().getProperty("DynamoDBProfileCredentials")).getCredentials(); 
} catch (Exception e) {
  log.error("Cannot load the credentials from the credential profiles file. " +
      "Please make sure that your credentials file is at the correct " +
      "location (C:\\Users\\your username\\credentials), and is in valid format.",e);
  throw new AmazonClientException(e);
}

上面的示例只是一個實現，而不是原始問題的答案。 要回答原始問題，您必須對API以及API設計產生的職責有清晰的了解。 您是否要在您的API中進行登錄還是要向調用方發出發生異常的信號？ 還是兩者都一樣（就像上面的示例一樣？）。

在使用異常或任何其他方式傳播意外狀態之前，請先回答以下問題：應如何處理這種情況？ 發生異常后應該怎么辦？ 日志記錄也不例外。 它只是記錄。 找到答案后，您可以尋找適當的方式傳達意外狀態。