winform开发中对App.Config的写和读操作

using System;
using System.Configuration;
using System.Collections.Generic;
using System.Text;
using System.Xml;
using System.Reflection;
namespace Common
{
/// <summary>
/// 对AppSettings节点进行增加，删除，修改操作.
/// </summary>
public static class AppSettingsHelper
{
public static string docName = String.Empty;
private static XmlNode node = null;
/// <summary>
/// 设置节点的值，若该节点不存在，则创建一个新的节点。
/// </summary>
/// <param name="key"></param>
/// <param name="value"></param>
/// <param name="cfgType"></param>
/// <returns></returns>
public static bool SetValue(string key, string value)
{
XmlDocument cfgDoc = new XmlDocument();
loadConfigDoc(cfgDoc);
// retrieve the appSettings node
node = cfgDoc.SelectSingleNode("//appSettings");
if (node == null)
{
throw new InvalidOperationException("appSettings section not found");
}
try
{
// XPath select setting "add" element that contains this key
XmlElement addElem = (XmlElement)node.SelectSingleNode("//add[@key='" + key + "']");
if (addElem != null)
{
addElem.SetAttribute("value", value);
}
// not found, so we need to add the element, key and value
else
{
XmlElement entry = cfgDoc.CreateElement("add");
entry.SetAttribute("key", key);
entry.SetAttribute("value", value);
node.AppendChild(entry);
}
//save it
saveConfigDoc(cfgDoc, docName);
return true;
}
catch
{
return false;
}
}
/// <summary>
/// 获取节点的值
/// </summary>
/// <param name="key"></param>
/// <param name="cfgType"></param>
/// <returns></returns>
public static string GetValue(string key)
{
XmlDocument cfgDoc = new XmlDocument();
loadConfigDoc(cfgDoc);
// retrieve the appSettings node
node = cfgDoc.SelectSingleNode("//appSettings");
if (node == null)
{
throw new InvalidOperationException("appSettings section not found");
}

// XPath select setting "add" element that contains this key
XmlElement addElem = (XmlElement)node.SelectSingleNode("//add[@key='" + key + "']");
if (addElem != null)
{

return addElem.GetAttribute("value");
}
// not found, so we need to add the element, key and value
else
{
throw new ArgumentException(string.Format("key '{0}' not found", key));
}
}
private static void saveConfigDoc(XmlDocument cfgDoc, string cfgDocPath)
{
try
{
XmlTextWriter writer = new XmlTextWriter(cfgDocPath, null);
writer.Formatting = Formatting.Indented;
cfgDoc.WriteTo(writer);
writer.Flush();
writer.Close();
return;
}
catch
{
throw;
}
}
/// <summary>
/// 移除节点
/// </summary>
/// <param name="elementKey"></param>
/// <param name="cfgType"></param>
/// <returns></returns>
public static bool RemoveElement(string elementKey)
{
try
{
XmlDocument cfgDoc = new XmlDocument();
loadConfigDoc(cfgDoc);
// retrieve the appSettings node
node = cfgDoc.SelectSingleNode("//appSettings");
if (node == null)
{
throw new InvalidOperationException("appSettings section not found");
}
// XPath select setting "add" element that contains this key to remove
node.RemoveChild(node.SelectSingleNode("//add[@key='" + elementKey + "']"));
saveConfigDoc(cfgDoc, docName);
return true;
}
catch
{
return false;
}
}
/// <summary>
/// 修改节点的值
/// </summary>
/// <param name="elementKey"></param>
/// <param name="cfgType"></param>
/// <returns></returns>
public static bool ModifyElement(string elementKey)
{
try
{
XmlDocument cfgDoc = new XmlDocument();
loadConfigDoc(cfgDoc);
// retrieve the appSettings node
node = cfgDoc.SelectSingleNode("//appSettings");
if (node == null)
{
throw new InvalidOperationException("appSettings section not found");
}
// XPath select setting "add" element that contains this key to remove
node.RemoveChild(node.SelectSingleNode("//add[@key='" + elementKey + "']"));
saveConfigDoc(cfgDoc, docName);
return true;
}
catch
{
return false;
}
}
private static XmlDocument loadConfigDoc(XmlDocument cfgDoc)
{
//docName = ((Assembly.GetEntryAssembly()).GetName()).Name;
docName = @"G:\C#\test\FileOperate\FileOperate\App.config";
//docName += ".config";
cfgDoc.Load(docName);
return cfgDoc;
}
}
}