asp.net core3.1 实战开发（配置文件的读取方式）

构造函数注入

 private readonly IConfiguration _iConfiguration;
 public ThirdController(IConfiguration configuration)
 {
     this._iConfiguration = configuration;
 }
 #endregion

 public IActionResult Index()
 {
//配置文件读取
 string allowedHost = this._iConfiguration["AllowedHost"].ToString();

 return View();
  }