c#同步备份文件夹文件（部分案例）

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
namespace 同步文件监视测试
{
    class Program
    {
       
        static string a = @"C:\Users\dell\Desktop\123";
        static string d = @"C:\Users\dell\Desktop\备份";
        //static string d = @"D:\备份";
        static DirectoryInfo fbeifen;
        static DirectoryInfo f123 = new DirectoryInfo(a);
        static  StreamReader rain;//不能放于循环体多次创建，要记住啊！！！
        static  StreamWriter saout;
        static  StringBuilder fff = new StringBuilder("");
        static FileSystemWatcher w;
        static void Main(string[] args)
        {
           
            w = new FileSystemWatcher(a);
            w.Changed += new FileSystemEventHandler(w_Changed);
            //w.NotifyFilter = NotifyFilters.CreationTime | NotifyFilters.LastWrite | NotifyFilters.FileName;
            w.EnableRaisingEvents = true;
            Console.Read();
        }
        static void w_Changed(object sender, FileSystemEventArgs e)
        {
            //此处可避免同时执行两次
            w.EnableRaisingEvents = false;
            System.Threading.Thread.Sleep(1000);
            w.EnableRaisingEvents = true;
            fbeifen = new DirectoryInfo(d);//注意这里，不能只用一个对象
            // 每次改变都会执行两次不知到为什么
                if (!fbeifen.Exists)
                {
                    try
                    {
                        fbeifen.Create();
                        Console.WriteLine("开始创建备份时间" + DateTime.Now.Ticks.ToString());
                        foreach (var item in f123.GetFiles())
                        {
                            rain = new StreamReader(item.DirectoryName + @"\" + item.Name,Encoding.GetEncoding("gb2312"));
                            File.Create(d + @"\" + item.Name).Close();
                            saout = File.AppendText(d + @"\" + item.Name);
                            saout.Write(rain.ReadToEnd());
                            rain.Close();
                            saout.Close();
                            //System.Threading.Thread.Sleep(100);
                        }
                        Console.WriteLine("创建备份成功！");
                    }
                    catch (Exception ex)
                    {
                        Console.WriteLine("创建备份失败！" + ex.Message);
                    }

                }
                else
                {
                    try
                    {
                        rain = new StreamReader(a + @"\" + e.Name,Encoding.GetEncoding("gb2312"));
                        File.Create(d + @"\" + e.Name).Close();
                        saout = File.AppendText(d + @"\" + e.Name);
                        saout.Write(rain.ReadToEnd());
                        rain.Close();
                        saout.Close();
                        Console.WriteLine(e.Name + "---文件更新备份成功！");
                    }
                    catch (Exception ex)
                    { Console.WriteLine("文件更新备份失败：" + ex.Message); }
                }
 
        }
    }
}