文件流操作（FileStream，StreamReader，StreamWriter）

大文件拷贝：

 /// <summary>
         /// 大文件拷贝
         /// </summary>
         /// <param name="sSource"></param>
         /// <param name="sTarget"></param>
         private static void CopyFile(string sSource, string sTarget)
         {
             using (FileStream fsRead=new FileStream(sSource,FileMode.Open,FileAccess.Read))
             {
                 using (FileStream fsWrite=new FileStream(sTarget,FileMode.Create,FileAccess.Write))
                 {
                     double n = (double)fsRead.Length;
                     Stopwatch sw = new Stopwatch();
 
                     sw.Start();
                     while (true)
                     {
                         //定义一个6MB的缓冲区
                         byte[] buffer = new byte[ *  * ];
                         int m = fsRead.Read(buffer, , buffer.Length);
 
                         if (m==)
                         {
                             break;
                         }
                         else
                         {
                             fsWrite.Write(buffer, , m);
                             double dl = Math.Round(((double)fsWrite.Position / n) * , );
                             Console.WriteLine("总进度：{0}%", dl);
                         }
                     }
                     sw.Stop();
                     double iTime = Math.Round((double)sw.ElapsedMilliseconds / , );
                     Console.WriteLine("总运行时间："+iTime+"秒");
                 }
             }
         }

FileStream是对字节(byte)的操作，上面这种方法拷贝电影文件，大的压缩文件等没问题，但是对于文本文件多半使用后面2个类StreamReader，StreamWriter，

 #region 使用StreamWriter进行写
             using (StreamWriter sw = new StreamWriter(@"D:\demo.txt"))
             {
                 for (int i = ; i <= ; i++)
                 {
                     sw.WriteLine(DateTime.Now.ToString("yyyy-MM-dd") + "\t" + i.ToString());
                 }
             }
             Console.WriteLine("OK");
             #endregion

 #region 使用StreamReader进行读
             using (StreamReader sr = new StreamReader(@"D:\demo.txt"))
             {
                 string s = sr.ReadLine();
                 while (!string.IsNullOrEmpty(s))
                 {
                     Console.WriteLine(s);
                     s = sr.ReadLine();
                 }
             }
             #endregion