原文地址:

.Net core http://cnblogs.com/WNpursue/p/10858727.html

.Net        http://cnblogs.com/123-4/p/3358600.html 

ConfigHelper:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Configuration;
 
 
 
namespace VisionControl
{
    static class ConfigHelper
    {
 
        /// <summary>
        /// 返回Config文件中对应Key的Val值
        /// </summary>
        /// <param name="str_Key">传入Key名称</param>
        /// <returns>对应Key的Val值</returns>
        public static string GetAppConfig(string str_Key)
        {
            string file = System.Windows.Forms.Application.ExecutablePath;
            Configuration config = ConfigurationManager.OpenExeConfiguration(file);
            foreach (string key in config.AppSettings.Settings.AllKeys)
            {
                if (key == str_Key)
                {
                    return config.AppSettings.Settings[str_Key].Value.ToString();
                }
            }
            return null;
 
 
        }
        /// <summary>
        /// 更新Config文件，若Key已存在，替换当前Val值；不存在则添加新的键值对
        /// </summary>
        /// <param name="str_newKey"></param>
        /// <param name="str_newVal"></param>
        public static void UpdateAppConfig(string str_newKey, string str_newVal)
        {
            string file = System.Windows.Forms.Application.ExecutablePath;
            Configuration config = ConfigurationManager.OpenExeConfiguration(file);
            bool exist = false;
            foreach (string key in config.AppSettings.Settings.AllKeys)
            {
                if (key == str_newKey)
                {
                    exist = true;
                }
            }
            if (exist)
            {
                config.AppSettings.Settings.Remove(str_newKey);
            }
            config.AppSettings.Settings.Add(str_newKey, str_newVal);
            config.Save(ConfigurationSaveMode.Modified);
            ConfigurationManager.RefreshSection("appSettings");
 
        }
    }
}

 其他:  http://cnblogs.com/8090sns/archive/2013/04/03/2997290.html