Configurationmanager.appsettings cannot be used in ASP. NET Core

Just approached. NET core, ready to migrate some of the previous technology tools first to. NET Standard, convenient for later use, the results of ConfigurationManager AppSettings there are various problems

First,

Error CS0012 type ' NameValueCollection ' is defined in unreferenced assemblies. You must add a reference to the assembly "System, version=4.0.0.0, Culture=neutral, publickeytoken=b77a5c561934e089".

Given the cross-platform of. NET Core and. NET Standard, System.dll should not get the system locally, so go to NuGet to find it, and then find it decisively.

Microsoft.NETCore.Portable.Compatiblity, which contains some system-level class libraries

But the result is still the same, and then continue to Baidu all kinds of information, the result is ... No results

Helpless only FQ help Google, the result let me find this

No configurationmanager in ASP. NET Core does not support

Resources

Https://www.danylkoweb.com/Blog/no-configurationmanager-in-aspnet-core-GC

https://stackoverflow.com/questions/40551232/ Configurationmanager-appsettings-generates-compile-time-error-on-net-standard-1

One way to get appsettings in Core

https://colinmackay.scot/2016/07/03/application-configuration-in-net-core-part-1/

Configurationmanager.appsettings cannot be used in ASP. NET Core