收到UDP数据时调用函数。 [英] Calling a function when UDP data recieved.

问题描述

你好，在c＃编程方面仍然不成熟，我编写了一个应用程序，它使用UDP协议从arduino接收数据，当我点击一个按钮数据发送和接收没有障碍，但我希望我的应用程序接收数据当arduino发送它时自动。所以我不会点击任何按钮或我不必手动触发任何事件。这是总代码。 PS即时通讯使用Visual Studio 2010 Express。





只有在arduino发送数据时才有办法接收数据吗？

请帮助



我尝试过：



< pre lang =c＃> private void button1_Click（ object sender，EventArgs e）
{
try
{
Socket SOCK = new Socket（AddressFamily.InterNetwork，SocketType.Dgram，ProtocolType.Udp）;
SOCK.ReceiveTimeout = 2000 ;
SOCK.SendTimeout = 2000 ;
IPAddress serverAddres = IPAddress.Parse（ 192.168.1.177）;
IPEndPoint endPoint = new IPEndPoint（serverAddres， 23 ）;
String text = textBox1.Text;
byte [] sendBuffer = Encoding.ASCII.GetBytes（text）;
SOCK.SendTo（sendBuffer，endPoint）;
byte [] recievedByte = new byte [ 1024 ];
int bytesrec = SOCK.Receive（recievedByte）;
textBox1.Text = Encoding.UTF8.GetString（recievedByte， 0 ，bytesrec）;
}
catch （Exception ex）
{
MessageBox.Show（ex.Message， 错误，MessageBoxButtons.RetryCancel，MessageBoxIcon.Error）;
}

}

解决方案

您需要附加异步回调 ¹ ，代表它接收套接字的数据，然后提醒您已收到数据。您无法附加接收功能，因为它可能会阻塞。您可以争辩说，

  //  您的收到调用也没用，所以就是这样， 
 SOCK.Receive（buffer，offset，SOCK.Available，SocketFlags.None）; 

会读取字节，但是不，因为即使在这种情况下，可用将为0，因为设备可能尚未发送消息，因此它将返回，充当非阻塞呼叫。一个好方法是使用回调，并执行BeginReceive（...），并从线路异步读取，

  //   Microsoft文档中的代码 
  //  开始从远程设备接收数据。  
 client.BeginReceive（state.buffer， 0 ，StateObject.BufferSize， 0 ，
  new  AsyncCallback（ReceiveCallback），state）; 

请查看此文档以了解有关该主题的更多信息，异步客户端套接字示例| Microsoft Docs [ ^ ]，如果您将其作为服务器应用程序写入，请仔细阅读，异步服务器套接字示例| Microsoft Docs [ ^ ]



1。我用斜体来表示，因为在21世纪考虑回调和异步方法很有趣。

Hi there, still not mature in c# programming, i have written an application in which it receives data from arduino using UDP protocol, when i click a button data is sent and received without hurdle, but i want my application to receive data automatically when arduino sends it. so that i wont click any button or i dont have to trigger any events manually. here is the total code. PS im using Visual Studio 2010 Express.


is there a way to receive data only when arduino sends it?
please help

What I have tried:

private void button1_Click(object sender, EventArgs e)
        {
            try
            {
                Socket SOCK = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
                SOCK.ReceiveTimeout = 2000;
                SOCK.SendTimeout = 2000;
                IPAddress serverAddres = IPAddress.Parse("192.168.1.177");
                IPEndPoint endPoint = new IPEndPoint(serverAddres, 23);
                String text = textBox1.Text;
                byte[] sendBuffer = Encoding.ASCII.GetBytes(text);
                SOCK.SendTo(sendBuffer, endPoint);
                byte[] recievedByte = new byte[1024];
                int bytesrec = SOCK.Receive(recievedByte);
                textBox1.Text = Encoding.UTF8.GetString(recievedByte, 0, bytesrec);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message,"Error", MessageBoxButtons.RetryCancel, MessageBoxIcon.Error);
            }

        }

解决方案

You need to attach the async callback¹, that receives the data for your socket, on its behalf and then alerts you that data has been received. You cannot attach a receive function, as it might be blocking. You can argue, that,

// Your receive call is useless as well, and so would be this, 
SOCK.Receive(buffer, offset, SOCK.Available, SocketFlags.None);

would read the bytes, but no, because even in this case, Available will be 0 as the device might have not yet sent a message, thus it will return, acting as a non-blocking call. A good approach is to use a callback, and do a BeginReceive(...), and asynchronously read from the wire,

// Code from Microsoft documentations
// Begin receiving the data from the remote device.  
client.BeginReceive( state.buffer, 0, StateObject.BufferSize, 0,  
     new AsyncCallback(ReceiveCallback), state);  

Please review this documentation to learn a bit more on the topic, Asynchronous Client Socket Example | Microsoft Docs[^], and if you are writin this as a server application, then go through this, Asynchronous Server Socket Example | Microsoft Docs[^]

1. I italicized that, because it is funny to consider a callback, and asynchronous approach in 21st century.

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