<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <appSettings>
    <add key="ConnectionString" value="server=192.168.100.116;database=BDCY;uid=sa;pwd=123456;" />
    <add key="ConnString" value="server=(local);database=gxjd;uid=sa;pwd=" />
    <add key="BakData" value="W1" />
    <add key="dogServer" value="192.168.100.116">
    </add>
    <add key="dogport" value="9898">
    </add>
  </appSettings>
</configuration>

   /// <summary>
        /// 读取XML中的数据数据库连接字符串
        /// </summary>
        /// <param name="value"></param>
        /// <param name="key"></param>
        /// <returns></returns>
        private string ConfigGetValues(string key)
        {
            string strRes = string.Empty;
            XmlDocument xDoc = new XmlDocument();
            xDoc.Load("Config.xml");
            XmlNode xNode;
            XmlElement xElement;
            xNode = xDoc.SelectSingleNode("//appSettings");
            xElement = (XmlElement)xNode.SelectSingleNode("add[@key=‘"+key+"‘]");
            if (xElement != null)
            {
                strRes = xElement.GetAttribute("value");
            }
            return strRes;
        }

  /// <summary>
        /// 写入XML中的数据
        /// </summary>
        /// <param name="key">键</param>
        /// <param name="value">值</param>
        /// <returns></returns>
        private void ConfigSetValues(string key,string value)
        {
            XmlDocument xDoc = new XmlDocument();
            xDoc.Load("Config.xml");
            XmlNode xNode;
            XmlElement xElement;
            XmlElement xElement1;
            xNode = xDoc.SelectSingleNode("//appSettings");
            xElement = (XmlElement)xNode.SelectSingleNode("//add[@key=‘"+key+"‘]");
            if (xElement != null)
            {
                xElement.SetAttribute("value", value); //"value"固定的AppStrings结点属性
            }
            else
            {
                xElement1 = xDoc.CreateElement("add");
                xElement1.SetAttribute("key", key);      //"key"固定的AppStrings结点属性
                xElement1.SetAttribute("value", value);  //"value"固定的AppStrings结点属性
                xNode.AppendChild(xElement1);
            }
            xDoc.Save("Config.xml");
        }

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Xml;

namespace Config
{
    public partial class XMLCheck : Form
    {
        public XMLCheck()
        {
            InitializeComponent();
        }

        //读取数据
        private void btnRead_Click(object sender, EventArgs e)
        {
            GetConfigSub("ConnectionString");
        }

        //写入数据
        private void btnWrite_Click(object sender, EventArgs e)
        {
            SetConfigSub();
            MessageBox.Show("修改成功！");
        }

        /// <summary>
        /// 读取XML中的数据数据库连接字符串
        /// </summary>
        /// <param name="value"></param>
        /// <param name="key"></param>
        /// <returns></returns>
        private string ConfigGetValues(string key)
        {
            string strRes = string.Empty;
            XmlDocument xDoc = new XmlDocument();
            xDoc.Load("Config.xml");
            XmlNode xNode;
            XmlElement xElement;
            xNode = xDoc.SelectSingleNode("//appSettings");
            xElement = (XmlElement)xNode.SelectSingleNode("add[@key=‘"+key+"‘]");
            if (xElement != null)
            {
                strRes = xElement.GetAttribute("value");
            }
            return strRes;
        }

        /// <summary>
        /// 获取数据库连接的子信息
        /// </summary>
        private void GetConfigSub(string key)
        {
            string strRes = ConfigGetValues(key);
            string[] arr = strRes.Split(‘;‘);
            txbServerName.Text =arr[0].Substring(arr[0].IndexOf(‘=‘)+1);
            txbDBName.Text = arr[1].Substring(arr[1].IndexOf(‘=‘) + 1);
            txbAccountName.Text = arr[2].Substring(arr[2].IndexOf(‘=‘) + 1);
            txbDBPwd.Text = arr[3].Substring(arr[3].IndexOf(‘=‘) + 1);
            txbDogAddress.Text = ConfigGetValues("dogServer");
        }

        /// <summary>
        /// 写入XML中的数据
        /// </summary>
        /// <param name="key">键</param>
        /// <param name="value">值</param>
        /// <returns></returns>
        private void ConfigSetValues(string key,string value)
        {
            XmlDocument xDoc = new XmlDocument();
            xDoc.Load("Config.xml");
            XmlNode xNode;
            XmlElement xElement;
            XmlElement xElement1;
            xNode = xDoc.SelectSingleNode("//appSettings");
            xElement = (XmlElement)xNode.SelectSingleNode("//add[@key=‘"+key+"‘]");
            if (xElement != null)
            {
                xElement.SetAttribute("value", value); //"value"固定的AppStrings结点属性
            }
            else
            {
                xElement1 = xDoc.CreateElement("add");
                xElement1.SetAttribute("key", key);      //"key"固定的AppStrings结点属性
                xElement1.SetAttribute("value", value);  //"value"固定的AppStrings结点属性
                xNode.AppendChild(xElement1);
            }
            xDoc.Save("Config.xml");
        }

        /// <summary>
        /// 设置数据库连接字符串
        /// </summary>
        private void SetConfigSub()
        {
            string serverName = "server=" + txbServerName.Text + ";";
            string dbName = "database=" + txbDBName.Text + ";";
            string dbAccount = "uid=" + txbAccountName.Text + ";";
            string dbPwd = "pwd=" + txbDBPwd.Text + ";";
            string dogServer = txbDogAddress.Text;
            string appSetting = serverName + dbName + dbAccount + dbPwd;
            ConfigSetValues("ConnectionString", appSetting);
            ConfigSetValues("dogServer", dogServer);
        }
    }
}