Asp.Net Core 如何获取IWebHostEnvironment

一、IWebHostEnvironment

服务器主机信息：

网站硬盘目录，网站名称，环境变量名称

    //
    // 摘要:
    //     Provides information about the web hosting environment an application is running
    //     in.
    public interface IWebHostEnvironment : IHostEnvironment
    {
        //
        // 摘要:
        //     Gets or sets the absolute path to the directory that contains the web-servable
        //     application content files.
        string WebRootPath { get; set; }
        //
        // 摘要:
        //     Gets or sets an Microsoft.Extensions.FileProviders.IFileProvider pointing at
        //     Microsoft.AspNetCore.Hosting.IWebHostEnvironment.WebRootPath.
        IFileProvider WebRootFileProvider { get; set; }
    }

    //
    // 摘要:
    //     Provides information about the hosting environment an application is running
    //     in.
    public interface IHostEnvironment
    {
        //
        // 摘要:
        //     Gets or sets the name of the application. This property is automatically set
        //     by the host to the assembly containing the application entry point.
        string ApplicationName { get; set; }
        //
        // 摘要:
        //     Gets or sets an Microsoft.Extensions.FileProviders.IFileProvider pointing at
        //     Microsoft.Extensions.Hosting.IHostEnvironment.ContentRootPath.
        IFileProvider ContentRootFileProvider { get; set; }
        //
        // 摘要:
        //     Gets or sets the absolute path to the directory that contains the application
        //     content files.
        string ContentRootPath { get; set; }
        //
        // 摘要:
        //     Gets or sets the name of the environment. The host automatically sets this property
        //     to the value of the of the "environment" key as specified in configuration.
        string EnvironmentName { get; set; }
    }

二、Startup中获取IWebHostEnvironment

        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
                // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
                app.UseHsts();
            }
            app.UseHttpsRedirection();
            app.UseStaticFiles();
           xxxx
        }

三、控制器中获取 IWebHostEnvironment

    public class UploadController : Controller
    {


        private readonly IWebHostEnvironment _env;
        public UploadController(IWebHostEnvironment env)
        {
            _env = env;
        }
}