如在asp.net Core的appsettings.json檔案里加入下面的配置

    "ConnectionStrings": {
      "SchoolContext": "Server=.;Database=SchoolContext;uid=sa;password=123456"
    }

在Models類庫裡的ConfigurationHelper類裡讀取

namespace Models
{
    public static class ConfigurationHelper
    {
        private static IConfiguration _config;
        public static void Configure(IConfiguration config)
        {
            _config = config;
        }

        //根據配置檔案鍵讀取對應的值
        public static string GetConfigValueByKey()
        {
            //var value = _config["ConnectionStrings:SchoolContext"];//這樣獲取："ConnectionStrings:SchoolContext"

            var value = _config.GetSection("ConnectionStrings")["SchoolContext"];

            if (value == null)
            {
                return "";
            }
            return value;
        }
    }
}
 

在asp.netCore專案的Startup類的建構函式裡進行注入

  public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
            ConfigurationHelper.Configure(Configuration);
        }

這樣執行專案時呼叫類庫的類裡就能在類庫裡讀取到配置檔案資訊。