详解C#如何读写config配置文件

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
 <appSettings>
 <add key="ServerIP" value="127.0.0.1"></add>
 <add key="DataBase" value="WarehouseDB"></add>
 <add key="user" value="sa"></add>
 <add key="password" value="sa"></add>
 </appSettings>
</configuration> 

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

namespace NetUtilityLib
{
 public static class ConfigHelper
 {
  //依据连接串名字connectionName返回数据连接字符串 
  public static string GetConnectionStringsConfig(string connectionName)
  {
   //指定config文件读取
   string file = System.Windows.Forms.Application.ExecutablePath;
   System.Configuration.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)
  {
   //指定config文件读取
   string file = System.Windows.Forms.Application.ExecutablePath;
   Configuration config = ConfigurationManager.OpenExeConfiguration(file);

   bool exist = false; //记录该连接串是否已经存在 
   //如果要更改的连接串已经存在 
   if (config.ConnectionStrings.ConnectionStrings[newName] != null)
   {
    exist = true;
   }
   // 如果连接串已存在，首先删除它 
   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);
   // 保存对配置文件所作的更改 
   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");
  }

  // 修改system.serviceModel下所有服务终结点的IP地址
  public static void UpdateServiceModelConfig(string configPath, string serverIP)
  {
   Configuration config = ConfigurationManager.OpenExeConfiguration(configPath);
   ConfigurationSectionGroup sec = config.SectionGroups["system.serviceModel"];
   ServiceModelSectionGroup serviceModelSectionGroup = sec as ServiceModelSectionGroup;
   ClientSection clientSection = serviceModelSectionGroup.Client;
   foreach (ChannelEndpointElement item in clientSection.Endpoints)
   {
    string pattern = @"\b\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\b";
    string address = item.Address.ToString();
    string replacement = string.Format("{0}", serverIP);
    address = Regex.Replace(address, pattern, replacement);
    item.Address = new Uri(address);
   }

   config.Save(ConfigurationSaveMode.Modified);
   ConfigurationManager.RefreshSection("system.serviceModel");
  }

  // 修改applicationSettings中App.Properties.Settings中服务的IP地址
  public static void UpdateConfig(string configPath, string serverIP)
  {
   Configuration config = ConfigurationManager.OpenExeConfiguration(configPath);
   ConfigurationSectionGroup sec = config.SectionGroups["applicationSettings"];
   ConfigurationSection configSection = sec.Sections["DataService.Properties.Settings"];
   ClientSettingsSection clientSettingsSection = configSection as ClientSettingsSection;
   if (clientSettingsSection != null)
   {
    SettingElement element1 = clientSettingsSection.Settings.Get("DataService_SystemManagerWS_SystemManagerWS");
    if (element1 != null)
    {
     clientSettingsSection.Settings.Remove(element1);
     string oldValue = element1.Value.ValueXml.InnerXml;
     element1.Value.ValueXml.InnerXml = GetNewIP(oldValue, serverIP);
     clientSettingsSection.Settings.Add(element1);
    }

    SettingElement element2 = clientSettingsSection.Settings.Get("DataService_EquipManagerWS_EquipManagerWS");
    if (element2 != null)
    {
     clientSettingsSection.Settings.Remove(element2);
     string oldValue = element2.Value.ValueXml.InnerXml;
     element2.Value.ValueXml.InnerXml = GetNewIP(oldValue, serverIP);
     clientSettingsSection.Settings.Add(element2);
    }
   }
   config.Save(ConfigurationSaveMode.Modified);
   ConfigurationManager.RefreshSection("applicationSettings");
  }

  private static string GetNewIP(string oldValue, string serverIP)
  {
   string pattern = @"\b\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\b";
   string replacement = string.Format("{0}", serverIP);
   string newvalue = Regex.Replace(oldValue, pattern, replacement);
   return newvalue;
  }
 }
} 

 class Program
 {
  static void Main(string[] args)
  {
   try
   {
    //string file = System.Windows.Forms.Application.ExecutablePath + ".config";
    //string file1 = AppDomain.CurrentDomain.SetupInformation.ConfigurationFile;
    string serverIP = ConfigHelper.GetAppConfig("ServerIP");
    string db = ConfigHelper.GetAppConfig("DataBase");
    string user = ConfigHelper.GetAppConfig("user");
    string password = ConfigHelper.GetAppConfig("password");

    Console.WriteLine(serverIP);
    Console.WriteLine(db);
    Console.WriteLine(user);
    Console.WriteLine(password);

    ConfigHelper.UpdateAppConfig("ServerIP", "192.168.1.11");
    string newIP = ConfigHelper.GetAppConfig("ServerIP");
    Console.WriteLine(newIP);

    Console.ReadKey();
   }
   catch (Exception ex)
   {
    Console.WriteLine(ex.Message);
   }
  }
 }