"Startup": {
    "Cors": {
      "PolicyName": "CorsIpAccess", //策略名称
      "EnableAllIPs": false, //当为true时，开放所有IP均可访问。     
      "IPs": "http://localhost:8080,http://localhost:8081,http://localhost:8021"
    }
  }

 #region CORS 跨域
         
            services.AddCors(c =>
            {
                if (!Configuration["Startup:Cors:EnableAllIPs"].ObjToBool())
                {
                    c.AddPolicy(Configuration["Startup:Cors:PolicyName"],
                        policy =>
                        {
                            policy
                            .WithOrigins(Configuration["Startup:Cors:IPs"].Split(‘,‘))
                            .AllowAnyHeader()
                            .AllowAnyMethod();
                        });
                }
                else
                {
                    //允许任意跨域请求
                    c.AddPolicy(Configuration["Startup:Cors:PolicyName"],
                        policy =>
                        {
                            policy
                            .SetIsOriginAllowed((host) => true)
                            .AllowAnyMethod()
                            .AllowAnyHeader()
                            .AllowCredentials();
                        });
                }

            });
            #endregion

#region CORS

            app.UseCors(Configuration["Startup:Cors:PolicyName"]);

            #endregion