c# – 拦截或装饰对ILogger的调用

2023年4月4日 505次阅读

我目前正在使用Castle windsor,以及我的应用程序中的日志记录工具.

但是,在我的日志记录中,我希望包含一些不在记录消息中但存储在CallContext中的上下文信息.

我试图通过使用以下方法拦截对ILogger的调用来做到这一点：

internal class Program
{
    private static void Main(string[] args)
    {
        var container = new WindsorContainer();
        container.AddFacility<LoggingFacility>(f => f.UseNLog());
        container.Kernel.Resolver.AddSubResolver(new LoggerResolver(container.Kernel));

        var logger = container.Resolve<ILogger>();
    }
}

public class LoggerResolver: ISubDependencyResolver
{
    private readonly IKernel _kernel;
    private static ProxyGenerator _proxyGenerator;

    static LoggerResolver()
    {
        _proxyGenerator = new ProxyGenerator();
    }

    public LoggerResolver(IKernel kernel)
    {
        _kernel = kernel;
    }

    public bool CanResolve(CreationContext context, ISubDependencyResolver contextHandlerResolver, ComponentModel model, DependencyModel dependency)
    {
        return dependency.TargetType == typeof(ILogger);
    }

    public object Resolve(CreationContext context, ISubDependencyResolver contextHandlerResolver, ComponentModel model, DependencyModel dependency)
    {
        return _proxyGenerator.CreateInterfaceProxyWithTarget(_kernel.Resolve<ILogger>(), new LoggingInterceptor());
    }
}

public class LoggingInterceptor: IInterceptor
{
    public void Intercept(IInvocation invocation)
    {
        //Some modification to message here
        invocation.Proceed();
    }
}

但是变量记录器的类型是NLog.Loggger,而不是我期望的动态代理.

最佳答案 一些挖掘ILSpy似乎表明你将无法拦截对ILogger实例化的调用. ILogger intance是由NLogFactory直接创建的(我查看的所有日志工厂,log4net,控制台等都是一样的)

// Castle.Services.Logging.NLogIntegration.NLogFactory
public override ILogger Create(string name)
{
    Logger logger = LogManager.GetLogger(name);
    return new NLogLogger(logger, this);
}

如果这确实是必要的,你应该能够继承你感兴趣的工厂(基本上是NLogFactory和ExtendedNLogFactory),以便覆盖ILogger的创建.然后创建ILogger的基于实例的代理并插入自定义拦截器.最后告知LoggingFacility您要使用自定义工厂.

我开始对你的问题感到悲观,但我发现解决方案很容易实现,所以你不应该有太多的问题来实现你想要的.
码？当然 ：)

public class MyFactory : NLogFactory
{
    public override ILogger Create(string name)
    {
        var il = base.Create(name);
        var pg =  new ProxyGenerator();
        return pg.CreateInterfaceProxyWithTarget<ILogger>(il, new LoggingInterceptor());
    }
}

public class LoggingInterceptor : IInterceptor
{
    public void Intercept(IInvocation invocation)
    {
        //Some modification to message here
        invocation.Proceed();
    }
}

internal class Program
{
    private static void Main(string[] args)
    {
        var container = new WindsorContainer();
        container.AddFacility<LoggingFacility>(f => f.UseNLog().LogUsing<MyFactory>());

        var logger = container.Resolve<ILogger>();
        logger.Debug("data"); // we intercept this call, success
        Console.ReadLine();
    }
}
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