C# 实现网络时间同步功能

using System;  
using System.Collections.Generic;  
using System.Linq;  
using System.Text;  
using System.IO;  
using System.Net;  
using System.Net.Sockets;  
using System.Text.RegularExpressions;  
using System.Runtime.InteropServices;
using System.Runtime;    



    /// <summary>  
    /// 网络时间  
    /// </summary>  
    public class NetTime
    {
       
        /// <summary>  
        /// 获取标准北京时间，读取http://www.beijing-time.org/time.asp  
        /// </summary>  
        /// <returns>返回网络时间</returns>  
        public DateTime GetBeijingTime()
        {
         
            DateTime dt;
            WebRequest wrt = null;
            WebResponse wrp = null;
            try
            {
                wrt = WebRequest.Create("http://www.beijing-time.org/time.asp");
                wrp = wrt.GetResponse();

                string html = string.Empty;
                using (Stream stream = wrp.GetResponseStream())
                {
                    using (StreamReader sr = new StreamReader(stream, Encoding.UTF8))
                    {
                        html = sr.ReadToEnd();
                    }
                }

                string[] tempArray = html.Split(';');
                for (int i = 0; i < tempArray.Length; i++)
                {
                    tempArray[i] = tempArray[i].Replace("
", "");
                }

                string year = tempArray[1].Split('=')[1];
                string month = tempArray[2].Split('=')[1];
                string day = tempArray[3].Split('=')[1];
                string hour = tempArray[5].Split('=')[1];
                string minite = tempArray[6].Split('=')[1];
                string second = tempArray[7].Split('=')[1];

                dt = DateTime.Parse(year + "-" + month + "-" + day + " " + hour + ":" + minite + ":" + second);
            }
            catch (WebException)
            {
                return DateTime.Parse("2011-1-1");
            }
            catch (Exception)
            {
                return DateTime.Parse("2011-1-1");
            }
            finally
            {
                if (wrp != null)
                    wrp.Close();
                if (wrt != null)
                    wrt.Abort();
            }
            return dt;

        }
    }

获取网络时间，返回一个DateTime对象，然后传给设置系统时间的方法，修改系统时间。下面是设置系统时间的代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Net;
using System.Net.Sockets;
using System.Text.RegularExpressions;
using System.Runtime.InteropServices;
using System.Runtime;    


    /// <summary>
    /// 更新系统时间
    /// </summary>
    public class UpdateTime
    {
        //设置系统时间的API函数
        [DllImport("kernel32.dll")]
        private static extern bool SetLocalTime(ref SYSTEMTIME time);

        [StructLayout(LayoutKind.Sequential)]
        private struct SYSTEMTIME
        {
            public short year;
            public short month;
            public short dayOfWeek;
            public short day;
            public short hour;
            public short minute;
            public short second;
            public short milliseconds;
        }

        /// <summary>
        /// 设置系统时间
        /// </summary>
        /// <param name="dt">需要设置的时间</param>
        /// <returns>返回系统时间设置状态，true为成功，false为失败</returns>
        public static bool SetDate(DateTime dt)
        {
            SYSTEMTIME st;

            st.year = (short)dt.Year;
            st.month = (short)dt.Month;
            st.dayOfWeek = (short)dt.DayOfWeek;
            st.day = (short)dt.Day;
            st.hour = (short)dt.Hour;
            st.minute = (short)dt.Minute;
            st.second = (short)dt.Second;
            st.milliseconds = (short)dt.Millisecond;
            bool rt = SetLocalTime(ref st);
            return rt;
        }
    }

需要注意的时，在win8系统上需要以管理员身份来运行程序，否则是无法设置系统时间的。下面这段代码可以设置让程序默认以管理员身份运行：

static void Main(string[] Args)
        {
            /**
             * 当前用户是管理员的时候，直接启动应用程序
             * 如果不是管理员，则使用启动对象启动程序，以确保使用管理员身份运行
             */
            //获得当前登录的Windows用户标示
            System.Security.Principal.WindowsIdentity identity = System.Security.Principal.WindowsIdentity.GetCurrent();
            //创建Windows用户主题
            Application.EnableVisualStyles();

            System.Security.Principal.WindowsPrincipal principal = new System.Security.Principal.WindowsPrincipal(identity);
            //判断当前登录用户是否为管理员
            if (principal.IsInRole(System.Security.Principal.WindowsBuiltInRole.Administrator))
            {
                //如果是管理员，则直接运行

                Application.EnableVisualStyles();
                Application.Run(new Form1());
            }
            else
            {
                //创建启动对象
                System.Diagnostics.ProcessStartInfo startInfo = new System.Diagnostics.ProcessStartInfo();
                //设置运行文件
                startInfo.FileName = System.Windows.Forms.Application.ExecutablePath;
                //设置启动参数
                startInfo.Arguments = String.Join(" ", Args);
                //设置启动动作,确保以管理员身份运行
                startInfo.Verb = "runas";
                //如果不是管理员，则启动UAC
                System.Diagnostics.Process.Start(startInfo);
                //退出
                System.Windows.Forms.Application.Exit();
            }
        }

搞定！