Dependency on Log4Net Logger and Retrieve Logger by Caller Type using Castle Windsor

问题

I have a thin wrapper around log4net and I am trying to use the type of the calling class to get a logger from log4net.LogManager by using Castle.Windsor.

public class Foo: IFoo
{
    private readonly ICommonLog _logger;

    public Foo(ICommonLog logger)
    {
        _logger = logger;
    }

    public void FooBar()
    {
        _logger.Info("Enter FooBar Method");
    }
}

public class CommonLog : ICommonLog
{
    private readonly log4net.ILog _logger;

    public CommonLog(Type loggerType)
    {
        _logger = log4net.LogManager.GetLogger(loggerType); 
    }

    public void Info(string message)
    {         
        _logger.Info(message.Cleanse());
    }

    // ...
}

I have tried this registration in Castle.Windsor (2.5.1) and I am able to get the correct logger for Foo. Am I mis-using dynamic parameters for this scenario? Is there a more elegant solution?

container.Register(Component.For<ICommonLog>().ImplementedBy(typeof(CommonLog)).
   LifeStyle.Transient);
container.Register(Component.For<IFoo>().ImplementedBy(typeof(Foo)).
   LifeStyle.Transient.DynamicParameters(
       (k, d) =>
       {
          var component = k.Resolve<ICommonLog>(new {loggerType = typeof (Foo)});
          d["logger"] = component;
          return r =>
          {
              if (component != null)
              {
                  r.ReleaseComponent(component);
              }
          };
       })
  );

Edit: I've updated the solution using ISubDependencyResolver:

public class LoggerResolver : ISubDependencyResolver
{
    private readonly IKernel kernel;

    public LoggerResolver(IKernel kernel)
    {
        this.kernel = kernel;
    }

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

    public object Resolve(CreationContext context,
                          ISubDependencyResolver contextHandlerResolver,
                          ComponentModel model,
                          DependencyModel dependency)
    {
        if (CanResolve(context, contextHandlerResolver, model, dependency))
        {
            return kernel.Resolve<ICommonLog>(new {loggerType = model.Implementation});
        }
        return null;
    }
}

Registration:

container.Register(Component.For<ICommonLog>().ImplementedBy(typeof(CommonLog))
    .LifeStyle.Transient);
container.Register(Component.For<IFoo().ImplementedBy(typeof(Foo))
    .LifeStyle.Transient);
container.Kernel.Resolver.AddSubResolver(new LoggerResolver(container.Kernel));

回答1:

You do not need to register CommonLog. Your sub dependency resolver can new one up for you.

container.Register(Component.For<IFoo>().ImplementedBy<Foo>().LifeStyle.Transient);
container.Kernel.Resolver.AddSubResolver(new LoggerResolver(container.Kernel));

public class LoggerResolver : ISubDependencyResolver
{
    ...

    public object Resolve(CreationContext context, ISubDependencyResolver contextHandlerResolver, ComponentModel model, DependencyModel dependency)
    {
        //No need to can resolve, Windsor will do this for you

        return new CommonLog(model.Implementation);
    }
}

EDIT Example of a logger provider

container.Register(Component.For<ILoggerProvider>().ImplementedBy<Log4NetLoggerProvider >().LifeStyle.Transient);

public interface ICommonLoggerProvider
{
    ICommonLog GetLogger( Type type );
}

public class Log4NetLoggerProvider : ICommonLoggerProvider
{
    public ICommonLog GetLogger(Type type)
    {
        return new Log4NetLogger(type);
    }
}

public class LoggerResolver : ISubDependencyResolver
{
    ...
    public object Resolve( CreationContext context, ISubDependencyResolver contextHandlerResolver, Castle.Core.ComponentModel model, DependencyModel dependency )
    {
        return kernel.Resolve<ICommonLoggerProvider>().GetLogger( model.Implementation );
    }
}

来源：https://stackoverflow.com/questions/9509115/dependency-on-log4net-logger-and-retrieve-logger-by-caller-type-using-castle-win

标签

.net

inversion-of-control

castle-windsor

log4net