c# - log4net logger wrapper 的实现和使用

Question

这个问题与Steven有关的答案 - here .他提出了一个非常好的记录器包装器。我将在下面粘贴他的代码:

public interface ILogger
{
    void Log(LogEntry entry);
}

public static class LoggerExtensions
{
    public static void Log(this ILogger logger, string message)
    {
        logger.Log(new LogEntry(LoggingEventType.Information,
            message, null));
    }

    public static void Log(this ILogger logger, Exception exception)
    {
        logger.Log(new LogEntry(LoggingEventType.Error, 
            exception.Message, exception));
    }

    // More methods here.
}

所以，我的问题是创建代理到 log4net 的实现的正确方法是什么？我应该只添加另一个带有类型参数的日志扩展方法，然后在里面创建一个开关吗？在 LoggingEventType 的情况下使用不同的 log4net 方法？

第二个问题，稍后在代码中使用它的最佳方式是什么？

因为他写道:

(…) you can easily create an ILogger implementation (…) and configure your DI container to inject it in classes that have a ILogger in their constructor.

这是否意味着每个将记录某事的类(基本上每个类)都应该在其构造函数中包含 ILogger？

Answer 1

So, my question is what is the proper way to create implementation that proxies to log4net?

你应该创建类似这样的东西:

public class Log4netAdapter : ILogger
{
    private readonly log4net.ILog m_Adaptee;

    public Log4netAdapter(log4net.ILog adaptee)
    {
        m_Adaptee = adaptee;
    }

    public void Log(LogEntry entry)
    {
        //Here invoke m_Adaptee
        if(entry.Severity == LoggingEventType.Debug)
            m_Adaptee.Debug(entry.Message, entry.Exception);
        else if(entry.Severity == LoggingEventType.Information)
            m_Adaptee.Info(entry.Message, entry.Exception);
        else if(entry.Severity == LoggingEventType.Warning)
            m_Adaptee.Warn(entry.Message, entry.Exception);
        else if(entry.Severity == LoggingEventType.Error)
            m_Adaptee.Error(entry.Message, entry.Exception);
        else
            m_Adaptee.Fatal(entry.Message, entry.Exception);
    }
}

Does that mean that every class that will log sth (so basically every), should have ILogger in its constructor?

据我从史蒂文斯的回答中了解到:是的，你应该这样做。

what is the best way to use it later in the code?

如果您使用的是 DI 容器，那么只需使用 DI 容器将 ILogger 映射到 Log4netAdapter。您还需要注册 log4net.ILog，或者只是将 log4net logger 的实例提供给 DI 容器以将其注入(inject) Log4netAdapter 构造函数。

如果您不使用 DI 容器，即您使用 Pure DI ，然后你做这样的事情:

ILog log = log4net.LogManager.GetLogger("MyClass");

ILogger logging_adapter = new Log4netAdapter(log);

var myobject = new MyClass(other_dependencies_here, logging_adapter);