.net 修改app.config自定义配置节点

<?xml version="1.0" encoding="utf-8" ?><!-- 样本 -->
<configuration>
    <configSections>
        <sectionGroup name="geoSettings">
            <section name="summary" type="System.Configuration.NameValueSectionHandler" />
        </sectionGroup>
    </configSections>

    <appSettings>
        <add key="Language" value="Ruby" />
        <add key="Version" value="1.9.3" />
    </appSettings>

    <geoSettings>
        <summary>
            <add key="Country" value="New Zealand" />
            <add key="City" value="Christchurch" />
        </summary>
    </geoSettings>
</configuration>

更新自定义配置节点

增加一个key

var xmlDoc = new XmlDocument();
xmlDoc.Load(AppDomain.CurrentDomain.SetupInformation.ConfigurationFile);

// create new node <add key="Region" value="Canterbury" />
var nodeRegion = xmlDoc.CreateElement("add");
nodeRegion.SetAttribute("key", "Region");
nodeRegion.SetAttribute("value", "Canterbury");

xmlDoc.SelectSingleNode("//geoSettings/summary").AppendChild(nodeRegion);
xmlDoc.Save(AppDomain.CurrentDomain.SetupInformation.ConfigurationFile);

ConfigurationManager.RefreshSection("geoSettings/summary");

编辑一个已存在的key的值

var xmlDoc = new XmlDocument();
xmlDoc.Load(AppDomain.CurrentDomain.SetupInformation.ConfigurationFile);

xmlDoc.SelectSingleNode("//geoSettings/summary/add[@key='Country']").Attributes["value"].Value = "Old Zeeland";
xmlDoc.Save(AppDomain.CurrentDomain.SetupInformation.ConfigurationFile);

ConfigurationManager.RefreshSection("geoSettings/summary");

删除一个已存在的key

var xmlDoc = new XmlDocument();
xmlDoc.Load(AppDomain.CurrentDomain.SetupInformation.ConfigurationFile);

XmlNode nodeCity = xmlDoc.SelectSingleNode("//geoSettings/summary/add[@key='City']");
nodeCity.ParentNode.RemoveChild(nodeCity);

xmlDoc.Save(AppDomain.CurrentDomain.SetupInformation.ConfigurationFile);
ConfigurationManager.RefreshSection("geoSettings/summary");

原文：http://yizeng.me/2013/08/31/update-appsettings-and-custom-configuration-sections-in-appconfig-at-runtime/