Java服务器客户端绑定(bind)错误

Question

我已经制作了一个服务器/客户端，设置为通过套接字进行通信。但是我在连接它们时遇到了一些问题。

首先，我在端口 7777(已打开)上启动服务器，然后启动客户端，但出现 java.net.BindException。我的编码错误吗？

服务器端:

public Server(int port) { // port = 7777
        this.port = port; // dont bother with this line
        try {
            socket = new DatagramSocket(port);
        } catch (SocketException ex) {
            return;
        }
        run = new Thread(this, "Server");
        run.start(); // starts thread to listen for sent client packets
    }

客户端:

private boolean openConnection(String address, int port) { // returns boolean to check for established connection as well as establish it, port = 7777
        try {
            socket = new DatagramSocket(port); // THE ERROR IN OUTPUT POINTS TO THIS LINE
            ip = InetAddress.getByName(address);
            return true;
        } catch (UnknownHostException | SocketException ex) {
            ex.printStackTrace();
            return false;
        }
    }

堆栈跟踪:

java.net.BindException: Address already in use: Cannot bind
    at java.net.DualStackPlainDatagramSocketImpl.socketBind(Native Method)
    at java.net.DualStackPlainDatagramSocketImpl.bind0(DualStackPlainDatagramSocketImpl.java:81)
    at java.net.AbstractPlainDatagramSocketImpl.bind(AbstractPlainDatagramSocketImpl.java:95)
    at java.net.DatagramSocket.bind(DatagramSocket.java:376)
    at java.net.DatagramSocket.<init>(DatagramSocket.java:231)
    at java.net.DatagramSocket.<init>(DatagramSocket.java:284)
    at java.net.DatagramSocket.<init>(DatagramSocket.java:256)
    at chatprogram.client.Client.openConnection(Client.java:45)
    at chatprogram.client.Client.<init>(Client.java:35)
    at chatprogram.client.Login1$8.run(Login1.java:104)
    at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:251)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:733)
    at java.awt.EventQueue.access$200(EventQueue.java:103)
    at java.awt.EventQueue$3.run(EventQueue.java:694)
    at java.awt.EventQueue$3.run(EventQueue.java:692)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:703)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)

CMD netstat -an 输出:

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Answer 1

不要在客户端创建DatagramSocket。只需创建一个Socket，这样它就不会在本地绑定(bind)到特定端口(就像服务器那样):

new Socket(address, port);