net core 3.1 讀取appsettings.json配置文件

.NET CORE 3.0新增了Worker Services的新項目模板，可以編寫長時間運行的后台服務，並且能輕松的部署成windows服務或linux守護程序。

讀取appsettings.json配置文件

{
"Logging": {
"LogLevel": {
"Default": "Information",
"Microsoft": "Warning",
"Microsoft.Hosting.Lifetime": "Information"
}
},
"ConnectionStrings": {
"sqlserverContext": "sqlserverContextvalue",
"mysqlContext": "mysqlContextvalue"
}
}

讀取ConnectionStrings

Main方法中添加代碼

public static void Main(string[] args)
{
　　var builder = new ConfigurationBuilder(); 　　builder.AddJsonFile("appsettings.json",true,true); 　　IConfigurationSection conf = builder.Build().GetSection("ConnectionStrings"); 　　AppSettings.SetAppSetting(conf); 　　CreateHostBuilder(args).Build().Run(); }

第一個GetSection定位第一層位置，比如ConnectionStrings，
第二個GetSection定位第二層位置，選擇ConnectionStrings中的sqlserverContext或mysqlContext

新建AppSettings類

    public class AppSettings
    {
        private static IConfigurationSection appSection = null;
        /// <summary>
        /// 獲取配置文件
        /// </summary>
        /// <param name="key"></param>
        /// <returns></returns>
        public static string GetAppSeting(string key)
        {
            if (appSection.GetSection(key) != null)
            {
                return appSection.GetSection(key).Value;
            }
            else
            {
                return "";
            }
        }
        /// <summary>
        /// 設置配置文件
        /// </summary>
        /// <param name="section"></param>
        public static void SetAppSetting(IConfigurationSection section)
        {
            appSection = section;
        }
    }

 private string ConnStr = AppSettings.GetAppSeting("mysqlContext");