visual studio的工程项目都会有config配置文件，我写了一个简单的类作为读取，写的有误请见谅。

首先要引入dll （visual studio自带的）

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace UtilityClassLibrary
{
    public class ConfigHelp
    {
        public static string GetAppSettingValue(string key)
        {
            string val = "";

            try
            {
                val = System.Configuration.ConfigurationManager.AppSettings[key];
            }
            catch(Exception ex)
            {
                val = "";
            }
            return val;
        }

        public static string GetConnectionString(string key)
        {
            string val = "";

            try
            {
                val=System.Configuration.ConfigurationManager.ConnectionStrings[key].ToString();
            }
            catch(Exception ex)
            {
                val = "";
            }
            return val;
        }


    }









}