当数据包未从服务器发送时，如何在 UDP 客户端中设置超时？

Question

我正在编写一个关于 UDP 套接字编程的简单程序。我正在使用数据报套接字。我必须将数据包从客户端发送到服务器。然后服务器随机决定是否发回数据包。客户端必须接受发送的数据包或等待 2 秒并假设数据包丢失。我无法处理数据包丢失的情况。

    System.out.println("Receiving message...");
    dsock.receive(dpack); // receive the packet
    System.out.println("Message received");

如果发送了数据包，一切正常，但是当没有发送数据包并且我仍然有这行代码时，我该如何处理？

Answer 1

您正在搜索 dsock.setSoTimeout(2 * 1000)（2*1000 = 2000 毫秒 = 2 秒）。这是 doc

Enable/disable SO_TIMEOUT with the specified timeout, in milliseconds. With this option set to a non-zero timeout, a call to receive() for this DatagramSocket will block for only this amount of time. If the timeout expires, a java.net.SocketTimeoutException is raised, though the DatagramSocket is still valid. The option must be enabled prior to entering the blocking operation to have effect. The timeout must be > 0. A timeout of zero is interpreted as an infinite timeout.

这将在两秒后引发 SocketTimeoutException，因此您必须捕获它。

Answer 2

您可以更改套接字的超时并接收消息，直到达到超时，如下所示：

try {
    dsock = new DatagramSocket();
    byte[] buf = new byte[1000];
    DatagramPacket dpack = new DatagramPacket(buf, buf.length);

    //...

    dsock.setSoTimeout(1000);   // set the timeout in millisecounds.

    while(true) {        // recieve data until timeout
        try {
             System.out.println("Receiving message...");
             dsock.receive(dpack); // receive the packet
             System.out.println("Message received");
        }
        catch (SocketTimeoutException e) {
            // timeout exception.
            System.out.println("Timeout reached!!! " + e);
            dsock.close();
        }
    }
catch (SocketException e) {
    System.out.println("Socket closed " + e);

}

当数据包未从服务器发送时，如何在 UDP 客户端中设置超时？

How to set a timeout in a UDP client for when a packet is not sent from server?

java

sockets

networking

udp

timeout