c# Config配置文件读写

 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 using System.Configuration;
 using System.Text.RegularExpressions;

 namespace PrintLableCode
 {
     /// <summary>
     /// 配置文件读写类
     /// </summary>
     public static class ConfigHelper
     {
         /// <summary>
         /// 根据连接串名称connectionName返回连接字符串
         /// </summary>
         /// <param name="connectionName"></param>
         /// <returns>connectionString</returns>
         public static string GetConnectionStringsConfig(string connectionName)
         {
             //指定config文件读取
             string file = System.Windows.Forms.Application.ExecutablePath;
             Configuration config = ConfigurationManager.OpenExeConfiguration(file);
             string connectionString =
                 config.ConnectionStrings.ConnectionStrings[connectionName].ConnectionString.ToString();
             return connectionString;
         }
         /// <summary>
         /// 更新连接字符串
         /// </summary>
         /// <param name="newName">连接字符串名称</param>
         /// <param name="newConString">连接字符串内容</param>
         /// <param name="newProviderName">数据提供程序名称</param>
         public static void UpdateConnectionStringsConfig(string newName, string newConString,string newProviderName)
         {
             string file = System.Windows.Forms.Application.ExecutablePath;
             Configuration config = ConfigurationManager.OpenExeConfiguration(file);

             bool exist = false;//记录是否存在该连接串
             if(config.ConnectionStrings.ConnectionStrings[newName] != null)
             {
                 exist = true;
             }
             //如果存在需要更改的连接串，先删除
             if (exist)
             {
                 config.ConnectionStrings.ConnectionStrings.Remove(newName);
             }
             //新建一个连接字符串实例
             ConnectionStringSettings mySettings =
                 new ConnectionStringSettings(newName,newConString,newProviderName);
             //将新的连接串添加到配置文件中
             config.ConnectionStrings.ConnectionStrings.Add(mySettings);
             //保存对配置文件的更改
             config.Save(ConfigurationSaveMode.Modified);
             //强制重新载入配置文件的ConnectionStrings配置节
             ConfigurationManager.RefreshSection("ConnectionStrings");
         }
         /// <summary>
         /// 返回*.exe.config文件中appSettings配置节的value项
         /// </summary>
         /// <param name="strKey"></param>
         /// <returns></returns>
         public static string GetAppConfig(string strKey)
         {
             string file = System.Windows.Forms.Application.ExecutablePath;
             Configuration config = ConfigurationManager.OpenExeConfiguration(file);
             foreach(string key in config.AppSettings.Settings.AllKeys)
             {
                 if(key == strKey)
                 {
                     return config.AppSettings.Settings[strKey].Value.ToString();
                 }
             }
             return null;
         }
         ///<summary>
         ///在*.exe.config文件中appSettings配置节增加一对键值对
         ///</summary>
         ///<param name="newKey"></param>
         ///<param name="newValue"></param>
         public static void UpdateAppConfig(string newKey, string newValue)
         {
             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 == newKey)
                 {
                     exist = true;
                 }
             }
             if (exist)
             {
                 config.AppSettings.Settings.Remove(newKey);
             }
             config.AppSettings.Settings.Add(newKey, newValue);
             config.Save(ConfigurationSaveMode.Modified);
             ConfigurationManager.RefreshSection("appSettings");
         }

 }