将依赖项注入DelegatingHandler [英] Inject dependency into DelegatingHandler

问题描述

我是依赖注入的新手，但是对Ninject和Ninject.Extensions.Logging到[Inject]我的ILogger的任何地方都满意.

I am new to dependency injection, but happy with Ninject and Ninject.Extensions.Logging to [Inject] my ILogger wherever i need it.

但是，某些 DelegatingHandlers 破坏了所有的乐趣.

However some DelegatingHandlers are spoiling all the fun.

public class HttpsHandler : DelegatingHandler
{
    [Inject]
    public ILogger Logger { get; set; }

    protected override Task<HttpResponseMessage> SendAsync(
            HttpRequestMessage request, CancellationToken cancellationToken)
        {
            if (!string.Equals(request.RequestUri.Scheme, "https", StringComparison.OrdinalIgnoreCase))
            {
                Logger.Info(String.Format("{0}: is using HTTP", request.RemoteAddress());
                return
                    Task.Factory.StartNew(
                        () =>
                        new HttpResponseMessage(HttpStatusCode.BadRequest)
                        {
                            Content = new StringContent("HTTPS Required")
                        });
            }

            return base.SendAsync(request, cancellationToken);
        }
 }

有人可以向我指出如何将Ninject.Extensions.Logger.Nlog2注入到委托处理程序中的Ilogger中的正确方向吗?

Could anyone point me in the right direction on how to Inject Ninject.Extensions.Logger.Nlog2 into Ilogger inside the delegatinghandlers?

更新

我认为Pete在评论中向我指出了正确的方向(谢谢！). 我在HttpsHandler中添加了以下构造函数:

I think Pete got me in the right direction in the comments (thanks!). I added the following constructor to the HttpsHandler:

public HttpsHandler()
        {
            var kernel = new StandardKernel();

            var logfactory = kernel.Get<ILoggerFactory>();
            this.Logger = logfactory.GetCurrentClassLogger();
        }

现在我的记录仪开始工作了！

and now i've got the Logger working!

我唯一剩下的问题是，这是正确的实现方式，还是反模式?

My only question left, is this the right way to do it, or is it a anti-pattern?

推荐答案

DelegatingHandlers在应用程序启动时仅在Web API中初始化一次.

DelegatingHandlers are only initialized once in Web API, at application start.

这是Web API的已知问题/设计功能(出于性能方面的考虑，我认为是这样)-在此处查看错误报告 http://aspnetwebstack.codeplex.com/workitem/62 .

This is a known issue/design feature of Web API (I presume for performance reasons) - see the bug report here http://aspnetwebstack.codeplex.com/workitem/62.

像您自己建议的那样使用构造函数初始化，仅在您具有单例类型的依赖项时才有效(这就是记录器起作用的原因).无论如何，如果要将分辨率委派给Web API DependencyResolver，则必须使用GetDependencyScope()(可以从HttpRequestMessage调用)，作为解决方法.

Using a constructor initialization like you suggested yourself, would only work if you have singleton-type dependencies (that' why you logger works). Regardless, if you want to delegate the resolution to Web API DependencyResolver you have to use GetDependencyScope(), which can be called off the HttpRequestMessage, as a workaround.

我发布了如何使用Ninject 前一段时间.您应该使用这种方法来解决您的依赖问题，因为在您当前的解决方案中，您已经将Ninject& amp;您的处理程序，这远非期望.

I posted a walkthrough on doing that with Ninject a while ago. You should use this approach to resolve your deendency, because with your current solution you have coupled Ninject & your handler, which is far from desired.

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