log4net - 使用自定义主题配置或扩展 log4net SmtpAppender

Question

如何为生成的电子邮件主题指定布局和转换模式？

BufferSize 需要小于或等于 1，因此不会发生缓冲。

Answer 1

CodeProject 文章log4net NonBufferedSmtpAppenderWithSubjectLayout看起来很有希望。

---

通过从所需的基本附加程序（在我的情况下为 SmtpPickupDirAppender）继承并添加 ILayout 属性，可以在 Append 方法中更改主题。

public class SmtpSubjectLayoutPickupDirAppender : log4net.Appender.SmtpPickupDirAppender
{
    public SmtpSubjectLayoutPickupDirAppender()
        : base()
    {

    }

    public ILayout SubjectLayout
    {
        get;
        set;
    }

    protected override void Append(log4net.Core.LoggingEvent loggingEvent)
    {
        if (this.BufferSize <= 1 && this.SubjectLayout != null)
        {
            StringWriter subjectWriter = new StringWriter(System.Globalization.CultureInfo.InvariantCulture);
            this.SubjectLayout.Format(subjectWriter, loggingEvent);
            this.Subject = subjectWriter.ToString();
        }

        base.Append(loggingEvent);
    }
}

然后可以通过指定一个 subjectLayout 属性来配置它以覆盖默认主题。

<appender name="SmtpPickupDirAppender" type="namespace.for.SmtpSubjectLayoutPickupDirAppender">
    <to value="to@domain.com" />
    <from value="from@domain.com" />
    <subject value="test logging message" />

    <subjectLayout type="log4net.Layout.PatternLayout, log4net">
        <conversionPattern value="Logging message - %message"/>
    </subjectLayout>

    <pickupDir value="C:\SmtpPickup" />
    <bufferSize value="1" />
    <lossy value="true" />
    <evaluator type="log4net.Core.LevelEvaluator">
        <threshold value="WARN"/>
    </evaluator>
    <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%newline%date [%thread] %-5level %logger [%property{NDC}] - %message%newline%newline%newline" />
    </layout>
</appender>

Answer 2

Here is another example of SmtpAppender with custom subjects.

Answer 3

你可以从Nuget下载

源代码和示例

Answer 4

因为之前建议使用 NuGet 版本的 SmtpAppenderWithSubjectLayout 的答案需要 log4net 版本 > 1.2.1，所以我使用了 NuGet 源代码，但将其修改为使用 log4net 1.2.1

public class SmtpAppenderWithSubjectLayout : SmtpAppender
{
    public PatternLayout SubjectLayout { get; set; }

    protected override void SendBuffer(LoggingEvent[] events)
    {
        PrepareSubject(events);

        base.SendBuffer(events);
    }

    protected virtual void PrepareSubject(IEnumerable<LoggingEvent> events)
    {
        var subjects = new List<string>();

        foreach (LoggingEvent @event in events)
        {
            if (Evaluator.IsTriggeringEvent(@event))
            {
                var subjectWriter = new StringWriter(System.Globalization.CultureInfo.InvariantCulture);
                SubjectLayout.Format(subjectWriter, @event);
                subjects.Add(subjectWriter.ToString());
            }
        }

        Subject = string.Join(", ", subjects.ToArray());
    }
}