在.NetCore库中使用IHostingEnvironment [英] Using IHostingEnvironment in .NetCore library

问题描述

我用Asp.net core构建一个应用程序，并创建一个.Net core class library用于单元测试，我想在我的库中使用IHostingEnvironment(用于获取文件的物理路径)，因此我将其添加到启动中.我的Asp.net核心应用程序服务的CS:

I build an application with Asp.net core, and i create a .Net core class library for unit testing, i want to use IHostingEnvironment in my library(for get physical path of a file ), so i added this to startup.cs of my Asp.net Core application Service:

 services.AddSingleton<IHostingEnvironment>();

在库中，我添加了对Asp.net应用程序的引用，在库中的类中，我写了:

and in Library i added reference to my Asp.net application, and in my class in library i write:

  private IHostingEnvironment _env;
    public Class1(IHostingEnvironment env)
    {
        _env = env;
    }

但是当我运行它时，它给了我这个错误:

but when i run it, it gives me this error:

以下构造函数参数的夹具日期不匹配:IHostingEnvironment env

the following constructor parameters did not have matching fixture date : IHostingEnvironment env

出什么问题了?我如何在.NetCore library中使用它?

what is the problem? how can i use it in .NetCore library?

我也使用这种方式:

        IServiceCollection services = new ServiceCollection();
        services.AddSingleton<IHostingEnvironment>();
        IServiceProvider provider = services.BuildServiceProvider();
        IHostingEnvironment service = provider.GetService<IHostingEnvironment>();
        var p = service.WebRootPath; // give this error: Cannot instantiate implementation type 'Microsoft.AspNetCore.Hosting.IHostingEnvironment' for service type 'Microsoft.AspNetCore.Hosting.IHostingEnvironment'

但它也不起作用.

推荐答案

注意:services.AddSingleton<IHostingEnvironment>();表示您正在单例范围内注册IHostingEnvironment作为IHostingEnvironment的实现(始终重用).

Note: services.AddSingleton<IHostingEnvironment>(); means you are registering IHostingEnvironment as an implementation for IHostingEnvironment in a singleton scope (always reuse).

由于无法创建接口的实例，因此会出现此错误.

Since you can't create an instance of an interface, you get this error.

定义要创建的类(实现IHostingEnvironment)，例如:

define the class you want to be created (that implements IHostingEnvironment), eg:

services.AddSingleton<IHostingEnvironment>(new HostingEnvironment());

背后的dotnet核心(托管nuget程序包)

在WebHostBuilder中，构造函数的第一行是:

Behind the scenes dotnet core (Hosting nuget package)

In the WebHostBuilder The first row in the constructor is:

this._hostingEnvironment = (IHostingEnvironment) new HostingEnvironment();

此主机托管环境随后由Webhost构建器填充了更多设置.

This hosting environment is later filled with more settings, by the webhost builder.

您应该查看其github页面或反编译源代码: https://github.com/aspnet/Hosting

You should look at their github page or decompile the sources: https://github.com/aspnet/Hosting

注意:HostingEnvironment的大多数属性/设置是在WebHostBuilder的Build()方法上设置的.如果您想自己进行定量/测试，则应自行设置这些属性，或者也可以在测试中加入WebHostBuilder.

Note: Most of the properties/settings of HostingEnvironment are set on Build() method of the WebHostBuilder. If you want to moq/test this yourself you should set these properties yourself or just also include the WebHostBuilder in your test.

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