关于文件流替换

Question

MyFileStream.Position = (count - 1) * 1048576;
                            MyFileStream.Write(data, 0, data.Length);
                            MyFileStream.Flush();我先获取一个文件流，然后我用这段代码去替换其中一部分，为什么不能替换呢？程序没有报错什么的，但是我读取被替换这一段的MD5值，还是没有改变

Answer 1

        /// <summary>
        /// 接受
        /// </summary>
        /// <param name="client"></param>
        /// <param name="ServerPath"></param>
        public void ReceiverFile(Socket client, string ServerPath)
        {
            byte[] errorPacket = new byte[] { };
            FileStream MyFileStream = null;
            int count = 0;
            string sMD5 = "";
            if (File.Exists(ServerPath))
            {
                MyFileStream = new FileStream(ServerPath, FileMode.Open, FileAccess.ReadWrite);
                string exists_file = MyFileStream.Length.ToString();//已传大小
                int packetCount = (int)(Convert.ToInt64(exists_file) / 1048576);//已传包的数量
                long cutFileSize = 1048576 * packetCount;
                while (true)
                {
                    byte[] index = TransferFile.ReceiveVarData(client);
                    byte[] bMD5 = TransferFile.ReceiveVarData(client);
                    byte[] data = TransferFile.ReceiveVarData(client);
                    string s = System.Text.Encoding.Unicode.GetString(data);
                    if (index.Length != 0)
                    {
                        count = Convert.ToInt32(System.Text.Encoding.Unicode.GetString(index));
                    }
                    sMD5 = System.Text.Encoding.Unicode.GetString(bMD5);
                    if (count * 1048576 <= cutFileSize)//验证已传文件MD5值
                    {
                        MyFileStream.Read(data, 0, data.Length);
                        string s1 = System.Text.Encoding.Unicode.GetString(data);
                        string cMD5 = GetMD5Hash(data);
                        if (cMD5 == sMD5)
                        {
                            TransferFile.SendVarData(client, System.Text.Encoding.Unicode.GetBytes("true"));
                        }
                        else
                        {
                            MyFileStream.Seek((count - 1) * 1048576, SeekOrigin.Begin);
                            MyFileStream.Write(data, 0, data.Length);
                            TransferFile.SendVarData(client, System.Text.Encoding.Unicode.GetBytes("error"));
                        }
                    }
                    else
                    {
                        string cMD5 = GetMD5Hash(data);
                        if (data.Length == 0)
                        {
                            break;
                        }
                        if (cMD5 == sMD5)
                        {
                            MyFileStream.Write(data, 0, data.Length);
                            TransferFile.SendVarData(client, System.Text.Encoding.Unicode.GetBytes("true"));
                        }
                        else
                        {
                            TransferFile.SendVarData(client, System.Text.Encoding.Unicode.GetBytes("error"));
                        }
                    }
                }
            }
            else
            {
                MyFileStream = new FileStream(ServerPath, FileMode.Create, FileAccess.Write);
                while (true)
                {
                    byte[] index = TransferFile.ReceiveVarData(client);
                    byte[] bMD5 = TransferFile.ReceiveVarData(client);
                    byte[] data = TransferFile.ReceiveVarData(client);
                    sMD5 = System.Text.Encoding.Unicode.GetString(bMD5);
                    string cMD5 = GetMD5Hash(data);
                    if (data.Length == 0)
                    {
                        break;
                    }
                    if (cMD5 == sMD5)
                    {
                        //将接收到的数据包写入到文件流对象   
                        MyFileStream.Write(data, 0, data.Length);
                        TransferFile.SendVarData(client, System.Text.Encoding.Unicode.GetBytes("true"));
                    }
                    else
                    {
                        TransferFile.SendVarData(client, System.Text.Encoding.Unicode.GetBytes("error"));
                    }
                }
            }
            MyFileStream.Close();
            client.Close();
        }
    }这个是接收方法的完整代码，问题是续传文件时改变了源文件，比对数据包的MD5值，不相等就替换，但是怎么都替换不了，下次比对MD5还是替换前的

Answer 2

hlep me
昨天弄很久都找不到原因

Answer 3

sMD5 = System.Text.Encoding.Unicode.GetString(bMD5);
                    if (count * 1048576 <= cutFileSize)//验证已传文件MD5值
                    {
                        MyFileStream.Read(data, 0, data.Length);
                        string s1 = System.Text.Encoding.Unicode.GetString(data);
                        string cMD5 = GetMD5Hash(data);
                        if (cMD5 == sMD5) 貌似你只能应该用s1 == sMD5 ?源文件变了就Truncate整个重写，不要只重写块

Answer 4

S1那个没用我是拿来比对data改变没有的，忘记删除了。源文件变了就Truncate整个重写，但是如果用户续传几个G的文件，就改动一点好像不划算啊，我想做的是他改了什么，我就把那些区块替换掉