求一个修改app.config的源码。
网上的例子太拙计了。都是很复杂的修改<appSettings>的

我要求一个

<configuration>
  <connectionStrings>
    <add name="connString" connectionString="xxxx"/>
  </connectionStrings>
</configuration>

的源码
[解决办法]
http://developer.51cto.com/art/200908/146303.htm

如果你觉得太拙了，那就放在xml中修改呗
[解决办法]
这有个类，可以试试。出处：http://zhidao.baidu.com/link?url=j6aNmKhCgJNJ4txoq3FVyiFw20hBI-KxuQzWR0AreM3RcJIVEIbFQ7Ve5geVP8AaVxx5NqrgJEa1hJHFf9XlKK

public class AppConfig
    {
        private XmlDocument Doc = new XmlDocument();
        private AppDomain Ad = AppDomain.CurrentDomain;
        public AppConfig()
        {
            Doc.Load(Ad.SetupInformation.ConfigurationFile);
        }
        public void LoadAppConfig()
        {
            Doc.Load(Ad.SetupInformation.ConfigurationFile);
        }
        public void SetAppValue(string key, string newValue)
        {
            Doc.SelectSingleNode("/configuration/appSettings/add[@key='" + key + "']").Attributes["value"].Value = newValue;
        }
        public void SaveAppConfig()
        {
            Doc.Save(Ad.SetupInformation.ConfigurationFile);
            Doc.Load(Ad.SetupInformation.ConfigurationFile);
        }
        public string GetAppValue(string key)
        {
            return Doc.SelectSingleNode("/configuration/appSettings/add[@key='" + key + "']").Attributes["value"].Value;
        }
    }