简单读写XML文件

IPAddress.xml   文件如下：

<?xml version="1.0" encoding="utf-8"?>
<IP>
      <IPAddress>192.168.0.120</IPAddress>
</IP>

在 Form 窗体(读取XML配置.Designer.cs)中有如下控件：

        private  System.Windows.Forms.Button  button1;          //“读取”按钮
        private  System.Windows.Forms.Button  button2;          //“修改”按钮
        private  System.Windows.Forms.TextBox  textBox1;     // 用于显示和修改IP地址
        private  System.Windows.Forms.Label  label1;              // 显示“IP地址：”
        private  System.Windows.Forms.Button  button3;          // “保存”按钮

读取XML配置.cs  文件如下：

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

namespace CS_Test
{
    public partial class 读取XML配置 : Form
    {
        public 读取XML配置()
        {
            InitializeComponent();
        }

        XmlDocument doc = null;
        XmlNodeList nodeList = null;
        string path =null;
        //读取
        private void button1_Click(object sender, EventArgs e)
        {
            doc = new XmlDocument();
            //读取文件地址
            path = Application.StartupPath.ToString();
            //MessageBox.Show(path);
            int n = path.LastIndexOf("bin\\Debug");
            path = path.Substring(0, n);
            doc.Load((path + "IPAddress.xml"));
            MessageBox.Show(path + "IPAddress.xml");

            if (doc != null)
            {
               nodeList = doc.GetElementsByTagName("IPAddress");
               textBox1.Text =
                  nodeList[0].FirstChild.Value.ToString();
            }
        }
        //修改
        private void button2_Click(object sender, EventArgs e)
        {
            textBox1.ReadOnly = false;
        }
        //保存
        private void button3_Click(object sender, EventArgs e)
        {
            string newIP = textBox1.Text.ToString();
            if (nodeList != null)
            {
                if (textBox1.Text.Trim() != "")
                {
                    //通过根节点创建新元素
                    XmlNode n = doc.CreateTextNode(textBox1.Text.Trim());
                    //通过父节点替换子节点
                    nodeList[0].ReplaceChild(n,nodeList[0].FirstChild);
                    doc.Save(path + "IPAddress.xml");
                    MessageBox.Show("IP地址修改成功！");
                    textBox1.ReadOnly = true;
                }
            }
        }
    }
    class ProgramXML
    {
        static void Main(string[] args)
        {
            Application.Run(new 读取XML配置());
        }
    }
}