using System;
using System.Collections.Generic;
using System.IO;
using System.Text;

namespace FileModTest
{
    class Program
    {
        static long position = 0;
        static void Main(string[] args)
        {
            string source = @"D:\SocketClientFile\W.P.S.9999.12012.2019.exe";
            string target = source + ".temp";
            FileCopy(source, target);
            Console.ReadKey();
        }

        private static void FileCopy(string sourcePath,string targetPath)
        {
            FileStream fsRead = null;
            FileStream fsWrite = null;
            try
            {
                fsRead = new FileStream(sourcePath, FileMode.Open);
                byte[] result = new byte[1024 * 1024 * 10];//10 MB缓冲区
                fsWrite = new FileStream(targetPath, FileMode.Truncate);
                fsWrite.Close();
                while (true)
                {
                    int count = fsRead.Read(result, 0, result.Length);
                    using ( fsWrite = new FileStream(targetPath, FileMode.Append))
                    {
                        if (count == 0)
                            break;
                        fsWrite.Write(result, 0, count);
                        position = fsWrite.Position;
                        Console.WriteLine("已完成 %{0}", (int)((double)fsWrite.Position * 100 / fsRead.Length));
                    }
                }
            }
            catch (Exception ex)
            {

                Console.WriteLine(ex.Message.ToString());
            }
            finally
            {
                if (fsRead != null)
                    fsRead.Close();
                if (fsWrite != null)
                    fsWrite.Close();
            }
        }

        //public async void CreateCopyOfFile()
        //{
        //    string dir = @"c:\Mukesh\files\";

        //    using (StreamReader objStreamReader = File.OpenText(dir + "test.txt"))
        //    {
        //        using (StreamWriter objStreamWriter = File.CreateText(dir + "copy_test.txt"))
        //        {
        //            await CopyFileToTarget(objStreamReader, objStreamWriter);
        //        }
        //    }
        //}

        //public async Task CopyFileToTarget(StreamReader objStreamReader, StreamWriter objStreamWriter)
        //{
        //    int num;
        //    char[] buffer = new char[0x1000];

        //    while ((num = await objStreamReader.ReadAsync(buffer, 0, buffer.Length)) != 0)
        //    {
        //        await objStreamWriter.WriteAsync(buffer, 0, num);
        //    }
        //}
    }
}