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[6 * 1024 * 1024];
                        int m = fsRead.Read(buffer, 0, buffer.Length);

                        if (m==0)
                        {
                            break;
                        }
                        else
                        {
                            fsWrite.Write(buffer, 0, m);
                            double dl = Math.Round(((double)fsWrite.Position / n) * 100, 1);
                            Console.WriteLine("总进度：{0}%", dl);
                        }
                    }
                    sw.Stop();
                    double iTime = Math.Round((double)sw.ElapsedMilliseconds / 1000, 2);
                    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 = 1; i <= 20; i++)
                {
                    sw.WriteLine(DateTime.Now.ToString("yyyy-MM-dd") + "	" + 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