1.写一个Helper类

using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Configuration.Json;
using System;
using System.IO;

namespace com.aaa.Helper
{
 
        public class AppSettingsHelper
        {
            public static IConfiguration Configuration { get; set; }
            static AppSettingsHelper()
            {
                //ReloadOnChange = true 当appsettings.json被修改时重新加载            
                Configuration = new ConfigurationBuilder()
                .Add(new JsonConfigurationSource { Path = "appsettings.json", ReloadOnChange = true })
                .Build();
            }

        } 
 
}

2.调用方法 

调用方法
 
string redis = AppSettingsHelper.Configuration["DBConnStr:Redis:ConnectionString"];

3.appsettings.json

{
    "Logging": {
        "LogLevel": {
            "Default": "Information",
            "Microsoft": "Warning",
            "Microsoft.Hosting.Lifetime": "Information"
        }
    },
    "DBConnStr": {
        "Redis": {
            "ConnectionString": "192.168.1.69:6379,abortConnect=false",
            "Db": 10
        },
 
        "WorkerId": 1 // 0-31
    },
    "AllowedHosts": "*"
}