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 = ; i < tempArray.Length; i++)
                 {
                     tempArray[i] = tempArray[i].Replace("\r\n", "");
                 }

                 string year = tempArray[].Split('=')[];
                 string month = tempArray[].Split('=')[];
                 string day = tempArray[].Split('=')[];
                 string hour = tempArray[].Split('=')[];
                 string minite = tempArray[].Split('=')[];
                 string second = tempArray[].Split('=')[];

                 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！