文件传输仅第一次成功，随后失败

Question

这是一个使用套接字 TCP 的文件传输发送/接收程序。此代码包含在客户端和服务器应用程序中，并且仅在第一次时才能正常工作。

第二次，将接收的一方得到 0 并且传输完成。如何修复它以便可以多次使用？

public static void sendFile(string filePath)
{
    FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read);
    string fileName = Path.GetFileName(filePath);
    byte[] fileData;
    try
    {
        //sending file name and file size to the server
        busy = true;
        fileSize = fs.Length;
        byte[] fileDetial = null;
        string detail =  fileName + "," + fileSize.ToString();
        fileDetial = Encoding.ASCII.GetBytes(detail);
        client.Send(fileDetial);

        //sending file data to the server

        fileData = new byte[packetSize];
        count = 0;
        sum = 0;
        Program.thFP.Start();                           // running transfer rate
        Program.fp.StatusLabel("Sending data...");
        transferRate.timeLeft();

        while (sum < fileSize)
        {
            fs.Seek(sum, SeekOrigin.Begin);
            fs.Read(fileData, 0, fileData.Length);
            count = client.Send(fileData, 0, fileData.Length, SocketFlags.None);
            sum += count;
            Program.fp.ProgressBarFileHandler(sum, fileSize);
        }
    }
    finally
    {
        busy = false;
        fs.Close();
        fileData = null;
        MessageBox.Show(string.Format("{0} sent successfully", fileName));
    }
}

我猜下面的代码完全没有问题..我认为问题出在 SENDFILE 方法中..但这里是 receiveFile 代码..它可能会有所帮助

public static void ReceiveFile()
{

    //receving file name and file size from server
    busy = true;
    byte[] commandData = new byte[1024];
    client.Receive(commandData);
    Console.WriteLine(Encoding.ASCII.GetString(commandData));
    string[] Command = Encoding.ASCII.GetString(commandData).Split(',');
    string fileName = Command[0];
    fileSize = Convert.ToInt64(Command[1]);
    Program.thFP.Start();                           // running transfer rate
    Program.fp.StatusLabel("Receiving data...");
    transferRate.timeLeft();

    // receiving the file data from server
    FileStream fs = new FileStream(@"D:\" + fileName, FileMode.Create, FileAccess.Write);
    byte[] fileData = new byte[packetSize];
    try
    {
        count = 0;
        sum = 0;
        while (sum < fileSize)
        {
            count = client.Receive(fileData,0,fileData.Length, SocketFlags.None);
            fs.Seek(sum, SeekOrigin.Begin);
            fs.Write(fileData, 0, fileData.Length);
            sum += count;
            Program.fp.ProgressBarFileHandler(sum,fileSize);
        }
    }
    finally
    {
        busy = false;
        fs.Close();
        fileData = null;
        MessageBox.Show(string.Format("{0} recevied successfully", fileName));
    }
}

Answer 1

我已经修复了代码。问题出在SendFile 方法中，而正是在FileStream

我应该丢弃它，这样我就可以用新路径再次初始化它

finally
{
    busy = false;
    fs.Dispose();   //here i fixed my mistake it was fs.Close()
    fileData = null;
    MessageBox.Show(string.Format("{0} sent successfully", fileName));
}

Answer 2

我建议您需要处理 FileStream。我建议将它包装在 using 块中，这样即使抛出异常，它也会始终被释放。

// receiving the file data from server
using (FileStream fs = new FileStream(@"D:\" + fileName, FileMode.Create, FileAccess.Write))
{
    byte[] fileData = new byte[packetSize];
    try
    {
        ...same code as before here...
    }
    finally
    {
         ...same code as before here...
    }
}

我总是建议将流包装在 using 块中。这意味着，如果您稍后返回并编辑代码，您引入一个在完成后不会处理流的代码路径的危险会更小。

我还将重组代码，使您的“成功”消息不在 finally 块中 - 它可能应该在 try 块的末尾。您当前的实现将在抛出异常时显示成功消息 - 因此文件可能会成功。