Question

我需要在我的应用程序中同时打开2个不同的套接字。一个是标准DatagramSocket，另一个是MulticastSocket。两者都有自己的端口。但是，当我尝试初始化它们时，我在创建第二个套接字时出错。错误如下：

05-23 10:37:57.011: ERROR/UDPInterface(15478): Exception occurred while initializing MulticastSocket: java.net.BindException: Address already in use

但是，因为我为两个套接字使用单独的端口，所以这不可能发生，对吧？或者是因为为MulticastSocket指定的端口已经在使用？然后错误消息没有任何意义，因为它正在谈论已经在使用的地址....：/

我创建了这样的套接字：

/**
 * Initially set the UnicastSocket to use.
 * <p>Called from the constructor to create a new DatagramSocket to use 
 * for receiving and sending unicast data over UDP.
 * @param address The address to initially use.
 * @param port The port to initially use.
 */
private void initUnicastSocket(Inet4Address address, int port){
    try{
        mUnicastSocket = new DatagramSocket(port, address);
        mUnicastSocket.setSoTimeout(SOCKET_TIME_OUT);
    } catch(SocketException se){
        Log.e(TAG, "Exception occurred while initializing UnicastSocket: " + se.toString());
    }
    if(mUnicastSocket != null){
        Log.d(TAG, "Socket initially set to " +
               mUnicastSocket.getLocalAddress() + ":" + UnicastSocket.getLocalPort());
    }
}

/**
 * Initially set the BroadcastSocket to use.
 * <p>Called from the constructor to create a new MulticastSocket to use 
 * for receiving and sending broadcast data over UDP.
 * @param address
 * @param port
 */
private void initBroadcastSocket(Inet4Address address, int port){
    try {
        mBroadcastSocket = new MulticastSocket(port);
        mBroadcastSocket.joinGroup(address);
        mBroadcastSocket.setSoTimeout(SOCKET_TIME_OUT);
    } catch (IOException ioe) {
        Log.e(TAG, "Exception occurred while initializing MulticastSocket: " + ioe.toString());
    }
    if(mBroadcastSocket != null){
        Log.d(TAG, "MulticastSocket initially set to " + mBroadcastSocket.getLocalAddress() +
                    ":" + mBroadcastSocket.getLocalPort());
    }
}

修改的

值得注意的是，普通的DatagramSocket将使用设备的IP地址，而MulticastSocket将使用可由用户配置的IP地址。

Answer 1

多播使用UDP数据包加上错误消息“初始化 MulticastSocket ”，因此问题是多播套接字。

我建议将套接字参数添加到日志消息中。这将使调试变得更加简单。

您的体验有以下几个原因：

您的代码的旧副本仍在运行
设备上有防火墙
还有另一个使用此端口的应用。尝试另外一个检查

Answer 2

我通过使用辅助DatagramSocket而不是MulticastSocket解决了这个问题。通过设置DatagramSocket.setBroadcast(true);，我可以发送/接收广播消息。

修改初始化逻辑：

/**
 * Initially set the BroadcastSocket to use.
 * <p>Called from the constructor to create a new DatagramSocket to use 
 * for receiving and sending broadcast data over UDP.
 * @param address
 * @param port
 */
private void initBroadcastSocket(Inet4Address address, int port){
    try {
        mBroadcastSocket = new DatagramSocket(port, address);
        mBroadcastSocket.setBroadcast(true);
        mBroadcastSocket.setSoTimeout(SOCKET_TIME_OUT);
    } catch (IOException ioe) {
        Log.e(TAG, "Exception occurred while initializing BroadcastSocket: " + ioe.toString());
    }
    if(mBroadcastSocket != null){
        Log.d(TAG, "BroadcastSocket initially set to " + mBroadcastSocket.getLocalAddress() +
                    ":" + mBroadcastSocket.getLocalPort());
    }
}

谢谢大家虽然为我花了很多时间。

同时打开多个套接字

2 个答案: