如何发送文件不止一次

Question

有两个 C# 项目：一个项目用于客户端，另一个项目用于服务器。第一步是运行服务器，然后选择一个目标文件夹，然后运行客户端项目，选择一些 text.txt 发送到服务器的目标文件夹。 只有客户端可以向服务器发送文件

演示：

1.choosing file target                       2.client sends
   +------------+                                
   | tar folder |          <----------------       text.txt 
   +------------+

这很好用，但我希望它每隔几分钟自动发送一次 text.txt，所以我添加了while(true) 循环和Thread.Sleep(10000)，但它总是给出异常。我的意思是，它不会让我多发送一次。

我正在尝试在客户端类中放置一个 while 循环：

 public Form1()
        {
            InitializeComponent();
        }


        private void button1_Click(object sender, EventArgs e)//browse btn
        {
            string n;
            byte[] b1;
            TcpClient client;
            OpenFileDialog op;
            Stream s;
            StreamWriter sw;
            op = new OpenFileDialog();

            if (op.ShowDialog() == DialogResult.OK)
            {
                string t = textBox1.Text;
                t = op.FileName;
                FileInfo fi = new FileInfo(textBox1.Text = op.FileName);
                n = fi.Name + "." + fi.Length;

                client = new TcpClient("127.0.0.1", 8100);//"127.0.0.1", 5055

                sw = new StreamWriter(client.GetStream());
                s = client.GetStream();
                b1 = File.ReadAllBytes(op.FileName);

                //  s = client.GetStream();
                while (true)
                {

                    s.Write(b1, 0, b1.Length);
                    sw.WriteLine(n);
                     sw.Flush();
                    //sw.Close();
                    s.Close();//added by me
 Thread.Sleep(18000);

                                   }
                sw.Flush();
                client.Close();

                // label2.Text = "File Transferred....";
            }
        }

服务器类：

public Form1()
        {
            InitializeComponent();
        }

        string rd;
        byte[] b1;
        string v;
        int m=20;//number of byts
        TcpListener list;
        TcpClient client;
        int port = 8100;//5050
        int port1 = 8100;//5055
        IPAddress localAddr = IPAddress.Parse("127.0.0.1");
        private void button1_Click(object sender, EventArgs e)//browse button
        {

            if (folderBrowserDialog1.ShowDialog() == DialogResult.OK)
            {

                    textBox1.Text = folderBrowserDialog1.SelectedPath;
                    list = new TcpListener(localAddr, port1);
                    list.Start();

                    Thread incoming_connection = new Thread(ic);
                    incoming_connection.Start();

            }
        }

        private void ic()
        {

            client = list.AcceptTcpClient();
            Stream s = client.GetStream();
            b1 = new byte[m];
            s.Read(b1,0, b1.Length);
            MessageBox.Show("pathh "+textBox1.Text);
            File.WriteAllBytes(textBox1.Text+"\\flag.txt", b1);// the left side us the name of the written file
            //list.Stop();
            //client.Close();
          //  label1.Text = "File Received......";
        }

        private void Form2_Load(object sender, EventArgs e)
        {
            list = new TcpListener(localAddr, port);
           // TcpListener list = new TcpListener(port);
            list.Start();
            TcpClient client = list.AcceptTcpClient();
            MessageBox.Show("Client trying to connect");
            StreamReader sr = new StreamReader(client.GetStream());
            rd = sr.ReadLine();
            v = rd.Substring(rd.LastIndexOf('.') + 1);
            m = int.Parse(v);
           // list.Stop();
           // client.Close();
        }

Related

Answer 1

尝试更改为：

while (true)
{
    using (var client = new TcpClient("127.0.0.1", 8100))//"127.0.0.1", 5055
    using (var sw = new StreamWriter(client.GetStream()))
    using (var s = client.GetStream())
    {
        b1 = File.ReadAllBytes(op.FileName);
        //  s = client.GetStream();
        s.Write(b1, 0, b1.Length);
        sw.WriteLine(n);
        sw.Flush();
    }
    Thread.Sleep(18000);
}

using 语句有助于处理对象。

或者，如果您想保持连接打开，请尝试：

using (var client = new TcpClient("127.0.0.1", 8100))//"127.0.0.1", 5055
while (true)
{
    using (var sw = new StreamWriter(client.GetStream()))
    using (var s = client.GetStream())
    {
        b1 = File.ReadAllBytes(op.FileName);
        //  s = client.GetStream();
        s.Write(b1, 0, b1.Length);
        sw.WriteLine(n);
        sw.Flush();
    }
    Thread.Sleep(18000);
}

Answer 2

好的，这是你的问题：

在第一个循环中，它按预期工作正常，因为一切都已正确初始化，但在发送第一个文件后，您调用 s.Close();

while (true)
{
s.Write(b1, 0, b1.Length);
sw.WriteLine(n);
sw.Flush();
//sw.Close();
s.Close();//added by me
Thread.Sleep(18000);
}

现在发生的情况是在第一个循环之后关闭流，然后在第二个循环中它已经“释放”。

修复移动 s.Close();跳出循环并进入断开按钮事件或应用程序关闭事件。

另外我建议不要使用 Thread.Sleep(interval); 这是因为 sleep 会冻结您的线程，而 .NET 中的主线程用于您的界面，因此冻结该线程非常糟糕。

像以前的帖子一样创建一个新线程：

using System.Threading;

Stream s;
byte[] b1;
TcpClient client;
OpenFileDialog op;
StreamWriter sw;
Thread thread = new Thread(sendFile);
string fn;
string n;
threadExit = false;
Int32 interval = 18000;

public Form1()
{
  InitializeComponent();
}
private void Form1_OnLoad(object sender,EventArgs e) {
  op = new OpenFileDialog();
  client = new TcpClient("127.0.0.1", 8100);//"127.0.0.1", 5055
  sw = new StreamWriter(client.GetStream());
  s = client.GetStream();
  //It would be your responsibility to move this code to the proper place
  //because now it tries to open the connection when your app loads
}
private void sendFile() {
  while (!threadExit)
  {
    b1 = File.ReadAllBytes(fn);
    s.Write(b1, 0, b1.Length);
    sw.WriteLine(n);
    sw.Flush();
    Thread.Sleep(interval);
  }
}

private void button1_Click(object sender, EventArgs e)
{
  if (op.ShowDialog() == DialogResult.OK)
  {
    fn = op.FileName;
    FileInfo fi = new FileInfo(textBox1.Text = op.FileName);
    n = fi.Name + "." + fi.Length;
    thread.Start();
  }
  //It would be a good idea to add an indicator to signal that another thread is trying to send the file at a set interval

}
private void Form1_Close(object sender, EventArgs e) {
  s.Close();
  client.Close();
  threadExit = true;
  Application.Exit();
}

并记住对该线程使用try catch块，否则如果发生异常，将无法很好地处理。另请记住，在此线程运行时关闭应用程序将使您的应用程序保持打开状态，直到您手动终止该进程，因此在应用程序关闭事件中记得终止线程。

而且 close 正在发送一个信号让线程退出，但它可能需要长达 18 秒才能完全退出，另一种解决方案是使用 thread.Abort();但这是一个肮脏的出口，它很可能会引发异常。

再次记住阅读线程，这是一个快速但糟糕的版本，它应该是在生产环境中的样子。