(Java/Android) Client-side Socket throwing IOException

问题

I'm trying to connect 2 Android devices through sockets, but why isn't it working? I've tried replacing the Host Address with IP Address but it didn't work out.

Server Side (extends AsyncTask):

ServerSocket server;
int port;
String hostName

server = new ServerSocket(0);
port = server.getLocalPort(); //is sent to client via OR code

for (Enumeration<NetworkInterface> en = NetworkInterface.getNetworkInterfaces(); en.hasMoreElements();) {
    NetworkInterface intf = en.nextElement();
    for (Enumeration<InetAddress> enumIpAddr = intf.getInetAddresses(); enumIpAddr.hasMoreElements();) {
        InetAddress inetAddress = enumIpAddr.nextElement();
        if (!inetAddress.isLoopbackAddress()) {
            hostName = inetAddress.getHostName(); //is sent to client via OR code
        }
    }
}

Socket client = server.accept();

Client Side (extends AsyncTask):

SocketAddress socketAddress = new InetSocketAddress(serverHostName, serverPort);
client = new Socket();
client.bind(null);
client.connect(socketAddress, SOCKET_TIMEOUT); //exception happens in this method
connected = true;

Here is the stack trace:

11-08 03:02:38.050: W/System.err(26424): java.net.SocketTimeoutException: failed to connect to /fe80::b652:7dff:feb5:ece2%wlan0%7 (port 54579) after 10000ms
11-08 03:02:38.090: W/System.err(26424):    at libcore.io.IoBridge.connectErrno(IoBridge.java:150)
11-08 03:02:38.090: W/System.err(26424):    at libcore.io.IoBridge.connect(IoBridge.java:112)
11-08 03:02:38.120: W/System.err(26424):    at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192)
11-08 03:02:38.160: W/System.err(26424):    at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:459)
11-08 03:02:38.210: W/System.err(26424):    at java.net.Socket.connect(Socket.java:848)
11-08 03:02:38.210: W/System.err(26424):    at com.example.virtualcard.QRInternetClientThread.doInBackground(QRInternetClientThread.java:55)
11-08 03:02:38.220: W/System.err(26424):    at android.os.AsyncTask$2.call(AsyncTask.java:264)
11-08 03:02:38.220: W/System.err(26424):    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
11-08 03:02:38.220: W/System.err(26424):    at java.util.concurrent.FutureTask.run(FutureTask.java:137)
11-08 03:02:38.230: W/System.err(26424):    at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:208)
11-08 03:02:38.230: W/System.err(26424):    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
11-08 03:02:38.230: W/System.err(26424):    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
11-08 03:02:38.230: W/System.err(26424):    at java.lang.Thread.run(Thread.java:856)

回答1:

I've solved my problem. Turns out I should have used this code on client before socket creation, AND I had to change the thing to work with IP addressed instead of host names.

InetAddress addr = InetAddress.getByName(serverIP);
SocketAddress socketAddress = new InetSocketAddress(addr, serverPort);

//here follows the old client code
SocketAddress socketAddress = new InetSocketAddress(serverHostName, serverPort);
client = new Socket();
client.bind(null);
client.connect(socketAddress, SOCKET_TIMEOUT); //exception happens in this method
connected = true;

来源：https://stackoverflow.com/questions/26813023/java-android-client-side-socket-throwing-ioexception