Question

我正在尝试从UDP端口6610读取所有流量，我可以在Wireshark中看到这些数据包。我为此做了一个简单的读者：

public class ReceiveUDP extends Thread {

private int port = 6610;
private byte[] buffer = new byte[256];
private DatagramSocket socket;
private DatagramPacket packet;

public ReceiveUDP() throws SocketException {
    socket = new DatagramSocket(port);
    packet = new DatagramPacket(buffer, buffer.length);
    System.out.println("Succesfull socket / packet creation");
}

@Override
public void run() {
    try {
        socket.receive(packet);
        System.out.println("Succeded!");
    } catch (IOException e) {
        System.out.println("Failed to receive packet"+e.getCause().getMessage());
    }
}

public static void main(String[] args) throws SocketException {
    new ReceiveUDP().start();
}

打印输出为：

Succesfull socket / packet creation

即。脚本锁定在socket.receive(packet)。我错过了什么吗？

Answer 1

它并没有完全锁定receive()，而{em>阻止 receive()。具体来说，它将在接收线上等待，直到出现问题为止。出于调试和测试的目的，您可以使用以下内容：

socket.setSoTimeout(5000); // Block for max 5 seconds

while (true) {
   try {
      s.receive(packet);
      System.out.println("Succeded!");
      break;
   } catch (SocketTimeoutException ste) {
      // Timeout reached, log this and try again.
      // Possibly keep track of the total number of tries and give up 
      // (break) if it exceeds a threshold.
      System.out.println("Timeout reached, will try again");
   } catch (IOException iox) {
      System.out.println("I/O Error: " + iox.getMessage());
      break;
   }
}

在套接字上使用超时通常不是一个坏主意，这可以防止您的应用无限期地等待。这对您来说是否合理取决于您的用例。

Answer 2

就像Joachim Sauer所指出的那样，目的地IP没有设置为我的IP。改变这个解决了我的问题。

简单的UDP阅读器

2 个答案: