如何通过Internet获取系统IP地址

Question

由于系统上可能连接了多个以太网或wlan，我如何知道哪个网络具有互联网连接？

Enumeration en;
            try {
                en = NetworkInterface.getNetworkInterfaces();
                while (en.hasMoreElements()) {
                    NetworkInterface ni = (NetworkInterface) en.nextElement();
                    Enumeration ee = ni.getInetAddresses();
                    System.out.println(ni.getName());
                    while (ee.hasMoreElements()) {
                        InetAddress ia = (InetAddress) ee.nextElement();
                        System.out.println(ia.getHostAddress());
                    }
                }
            } catch (SocketException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

Answer 1

查看以下代码：

public static void main(String[] args) {
        Enumeration en;
        boolean connected;
        int timeOut = 5000;
        try {
            en = NetworkInterface.getNetworkInterfaces();
            while (en.hasMoreElements()) {
                NetworkInterface ni = (NetworkInterface) en.nextElement();
                Enumeration ee = ni.getInetAddresses();
                System.out.println(ni.getName());
                while (ee.hasMoreElements()) {
                    InetAddress ia = (InetAddress) ee.nextElement();
                    ia.getByName("www.google.com");

                    connected = ia.isReachable(timeOut);
                    if (connected == true) {
                        System.out.println(ia.getHostAddress());
                    }
                }

            }
        } catch (SocketException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (UnknownHostException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }