在这种情况下，一般异常处理不是那么糟糕吗？ [关闭]

Question

在下面的代码中，我尝试发送一组通知，我想知道通知是否发送成功（稍后将其放入数据库中，因此不再发送）。

我在这里抓到Exception 是不是很糟糕？我真的不在乎未发送通知的原因。

private static async Task<List<Tuple<NotificationToSend, bool>>> SendNotificationsAsync(IEnumerable<NotificationToSend> notificationsToSend)
{
    var tuples = new List<Tuple<NotificationToSend, bool>>();

    using (var smtpClient = new SmtpClient())
    {
        foreach (var notification in notificationsToSend)
        {
            bool sentSuccessfully;

            try
            {
                var mailMessage = new MailMessage
                {
                    Subject = notification.Subject,
                    Body = $"{notification.Text} <br /> This notification was sent automatically",
                    IsBodyHtml = true
                };

                mailMessage.To.Add(notification.ToEmail);

                await smtpClient.SendMailAsync(mailMessage);
                sentSuccessfully = true;
            }
            catch (Exception e)
            {
                sentSuccessfully = false;
                // Here I also plan to log the exception
            }

            var tuple = new Tuple<NotificationToSend, bool>(notification, sentSuccessfully);
            tuples.Add(tuple);
        }
    }

    return tuples;
}

Answer 1

你永远不应该使用catch(Exception e)，你应该只捕获你知道可以抛出的异常。并且使用 SmtpClient the MSDN documentation 表示可以抛出以下四个异常之一：

• ArgumentNullException
• InvalidOperationException
• ObjectDisposedException
• SmtpException

所以你应该这样做：

var sentSuccessfully = false;

var mailMessage = new MailMessage
{
    Subject = notification.Subject,
    Body = $"{notification.Text} <br /> This notification was sent automatically",
    IsBodyHtml = true
};

MailMessage.To.Add(notification.ToEmail);

try
{
    await smtpClient.SendMailAsync(mailMessage);
    sentSuccessfully = true;
}
catch (ArgumentNullException e)
{
    sentSuccessfully = false;
    // Handle Argument Exception
}
catch (InvalidOperationException e)
{
    sentSuccessfully = false;
    // Handle InvalidOperation Exception
}
catch (ObjectDisposedException e)
{
    // This one shouldn't happen, so you could leave it out
    sentSuccessfully = false;
    // Do Handle ObjectDisposed Exception
}
catch (SmtpException e)
{
    sentSuccessfully = false;
    // Handle Smtp Exception
}

这样做的原因是更好的日志记录，如果您知道引发的异常，日志可能会显示类似“ArgumentNullException was throw, *insert a possible explanation for why*”

或者如果您想以相同的方式处理所有异常：

try
{
    await smtpClient.SendMailAsync(mailMessage);
    sentSuccessfully = true;
}
catch (Exception e) when (e is ArgumentNullException || 
    e is InvalidOperationException || 
    e is ObjectDisposedException || 
    e is SmtpException)
{
    sentSuccessfully = false;
    // Handle exception
}

Answer 2

取决于您想要实现的行为。 即使有人在 try...catch 中引入了诸如空引用之类的直截了当的错误，像这样的一揽子捕获也会使程序“跛行”。通常这是不希望的，最好快速失败。

如果您希望程序仅在“预期”的 SMTP 基础结构错误之后继续运行，则仅捕获特定类型的异常（例如 SmtpException 或 SendMailAsync 可能引发的任何异常），否则让异常冒泡。

Answer 3

我的目标：

private static async Task<List<Tuple<NotificationToSend, bool>>> SendNotificationsAsync(IEnumerable<NotificationToSend> notificationsToSend)
{
    var tuples = new List<Tuple<NotificationToSend, bool>>();

    using (var smtpClient = new SmtpClient())
    {
        foreach (var notification in notificationsToSend)
        {
            bool sentSuccessfully = SendNotificationAsync(smtpClient, notification);

            var tuple = new Tuple<NotificationToSend, bool>(notification, sentSuccessfully);
            tuples.Add(tuple);
        }
    }

    return tuples;
}

private static async Task<bool> SendNotificationAsync(SmtpClient smtpClient, NotificationToSend notification)
{
    var mailMessage = new MailMessage
    {
        Subject = notification.Subject,
        Body = $"{notification.Text} <br /> This notification was sent automatically",
        IsBodyHtml = true
    };

    mailMessage.To.Add(notification.ToEmail);

    try
    {
        await smtpClient.SendMailAsync(mailMessage);
        return true;
    }
    catch (Exception e)
    {
        // Here I also plan to log the exception
        return false;
    }
}