在. net Core 2.0 MVC app / Microsoft.AspNetCore.All v2.0.0中，你可以有@vaindil所描述的特定于环境的启动类，但我不喜欢这种方法。

你也可以在StartUp构造函数中注入IHostingEnvironment。不需要将环境变量存储在Program类中。

public class Startup
{
    private readonly IHostingEnvironment _currentEnvironment;
    public IConfiguration Configuration { get; private set; }

    public Startup(IConfiguration configuration, IHostingEnvironment env)
    {
        _currentEnvironment = env;
        Configuration = configuration;
    }

    public void ConfigureServices(IServiceCollection services)
    {
        ......

        services.AddMvc(config =>
        {
            // Requiring authenticated users on the site globally
            var policy = new AuthorizationPolicyBuilder()
                .RequireAuthenticatedUser()
                .Build();
            config.Filters.Add(new AuthorizeFilter(policy));

            // Validate anti-forgery token globally
            config.Filters.Add(new AutoValidateAntiforgeryTokenAttribute());

            // If it's Production, enable HTTPS
            if (_currentEnvironment.IsProduction())      // <------
            {
                config.Filters.Add(new RequireHttpsAttribute());
            }            
        });

        ......
    }
}

我想在我的服务中加入这种环境。这真的很容易做到!我只是像这样把它注入到构造函数中:

    private readonly IHostingEnvironment _hostingEnvironment;

    public MyEmailService(IHostingEnvironment hostingEnvironment)
    {
        _hostingEnvironment = hostingEnvironment;
    }

现在在稍后的代码中，我可以这样做:

if (_hostingEnvironment.IsProduction()) {
    // really send the email.
}
else {
    // send the email to the test queue.
}

编辑:

上面的代码是用于。net Core 2的。对于版本3，您将使用IWebHostEnvironment。

在. net Core 2.0 MVC app / Microsoft.AspNetCore.All v2.0.0中，你可以有@vaindil所描述的特定于环境的启动类，但我不喜欢这种方法。

你也可以在StartUp构造函数中注入IHostingEnvironment。不需要将环境变量存储在Program类中。

public class Startup
{
    private readonly IHostingEnvironment _currentEnvironment;
    public IConfiguration Configuration { get; private set; }

    public Startup(IConfiguration configuration, IHostingEnvironment env)
    {
        _currentEnvironment = env;
        Configuration = configuration;
    }

    public void ConfigureServices(IServiceCollection services)
    {
        ......

        services.AddMvc(config =>
        {
            // Requiring authenticated users on the site globally
            var policy = new AuthorizationPolicyBuilder()
                .RequireAuthenticatedUser()
                .Build();
            config.Filters.Add(new AuthorizeFilter(policy));

            // Validate anti-forgery token globally
            config.Filters.Add(new AutoValidateAntiforgeryTokenAttribute());

            // If it's Production, enable HTTPS
            if (_currentEnvironment.IsProduction())      // <------
            {
                config.Filters.Add(new RequireHttpsAttribute());
            }            
        });

        ......
    }
}

如果你需要在你的代码库中某个不容易访问IHostingEnvironment的地方测试这个，另一个简单的方法是这样做的:

bool isDevelopment = Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT") == "Development";

你可以很容易地在ConfigureServices中访问它，只是在Startup方法期间将它持久化到一个属性，该方法首先被调用并将其传递进来，然后你可以从ConfigureServices访问该属性。

public Startup(IWebHostEnvironment env, IApplicationEnvironment appEnv)
{
    ...your code here...
    CurrentEnvironment = env;
}

private IWebHostEnvironment CurrentEnvironment{ get; set; } 
 
public void ConfigureServices(IServiceCollection services)
{
    string envName = CurrentEnvironment.EnvironmentName;
    ... your code here...
}

宿主环境来自ASPNET_ENV环境变量，在启动过程中使用IHostingEnvironment可用。IsEnvironment扩展方法，或IsDevelopment或IsProduction中相应的方便方法之一。在Startup()中保存你需要的东西，或者在ConfigureServices调用中保存:

var foo = Environment.GetEnvironmentVariable("ASPNET_ENV");