一，命名空间
using System;
using System.Configuration;
using System.Xml;
二，方法
//读取Value值
public static string GetConfigString(string key)
{
//
// TODO: 在此处添加构造函数逻辑
//
return ConfigurationSettings.AppSettings[key];
}
//写操作
public static void SetValue(string AppKey,string AppValue)
{
XmlDocument xDoc = new XmlDocument();
//获取可执行文件的路径和名称
xDoc.Load(System.Windows.Forms.Application.ExecutablePath + ".config");

XmlNode xNode;
XmlElement xElem1;
XmlElement xElem2;
xNode = xDoc.SelectSingleNode("//appSettings");

xElem1 = (XmlElement)xNode.SelectSingleNode("//add[@key='" + AppKey + "']");
if ( xElem1 != null ) xElem1.SetAttribute("value",AppValue);
else
{
xElem2 = xDoc.CreateElement("add");
xElem2.SetAttribute("key",AppKey);
xElem2.SetAttribute("value",AppValue);
xNode.AppendChild(xElem2);
}
xDoc.Save(System.Windows.Forms.Application.ExecutablePath + ".config");
}