asp.net-core - 如何在中间件类中访问 IHostingEnvironment

Question

在 Asp.Net Core 中，如果创建了一个自定义中间件并将其放置在它自己的类中，如何访问 IHostingEnvironment从中间件内部？

例如，在我下面的类(class)中，我认为我可以注入(inject) IHostingEnvironment进入构造函数，但它始终为空。关于如何访问 IHostingEnvironment 的任何其他想法?

public class ForceHttps {
    private readonly RequestDelegate _next;
    private readonly IHostingEnvironment _env;

    /// <summary>
    /// This approach to getting access to IHostingEnvironment 
    /// doesn't work.  It's always null
    /// </summary>
    /// <param name="next"></param>
    /// <param name="env"></param>
    public ForceHttps(RequestDelegate next, IHostingEnvironment env) {
        _next = next;
    }


    public async Task Invoke(HttpContext context) {
        string sslPort = "";
        HttpRequest request = context.Request;


        if(_env.IsDevelopment()) {
            sslPort = ":44376";
        }

        if(request.IsHttps == false) {
            context.Response.Redirect("https://" + request.Host + sslPort + request.Path);
        }

        await _next.Invoke(context);

    }
}

Answer 1

方法注入(inject)有效，只需将其添加到方法签名中

 public async Task Invoke(HttpContext context, IHostingEnvironment env) {...}