简单的注射器：如何注入HttpContext的？

问题描述

我已经开始使用简单的注射器作为我的DI容器（主要是出于性能的原因：如果有人有意见，请让我知道），但一些类，我写使用HttpContextBase作为构造函数的参数。我已经解决了，现在从构造函数中删除并创建一个属性，是这样的：

I have started using Simple Injector as my DI container (mostly for performance reason: if somebody has suggestions, please let me know) but some of the classes I wrote use HttpContextBase as constructor parameter.I have resolved for now removing it from the constructor and creating a Property, something like this:

    public HttpContextBase HttpContext
    {
        get
        {
            if (null == _httpContext)
                _httpContext = new HttpContextWrapper(System.Web.HttpContext.Current);
            return _httpContext;
        }
        set
        {
            _httpContext = value;
        }
    }

但我不喜欢这种解决方案有何意见？

but I don't like this solution... any advices?

推荐答案

您应该总是青睐构造注射过任何东西。这几乎总是可能的。你可以注册 HttpContextBase 如下：

You should always favor constructor injection over anything else. This is almost always possible. You can register your HttpContextBase as follows:

container.RegisterPerWebRequest<HttpContextBase>(() =>
    new HttpContextWrapper(HttpContext.Current));

这可以在调用验证（），因为在应用程序启动 HttpContext.Current 是，当出现问题了空和 HttpContextWrapper 不允许传递空到构造函数。

This can cause a problem when calling Verify(), since during application startup HttpContext.Current is null, and HttpContextWrapper does not allow passing null into the constructor.

它总是好的尝试让您的配置可验证，您可以更改登记为以下内容：

It's always good to try to keep your configuration verifiable, and you can change that registration to the following:

// using SimpleInjector.Advanced;

container.RegisterPerWebRequest<HttpContextBase>(() =>
{
    var context = HttpContext.Current;
    if (context == null && container.IsVerifying()) return new FakeHttpContext();
    return new HttpContextWrapper(context);
});

FakeHttpContext 是一个空的 HttpContextBase 执行prevent返回空的情况下，容器的检验。该 FakeHttpContext 很简单：

FakeHttpContext is an empty HttpContextBase implementation to prevent returning null in case the container is verifying. The FakeHttpContext is simply this:

public class FakeHttpContext : HttpContextBase { }

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