見程式碼

        // 正確的IP拿法，即優先拿site-local地址
        @SuppressWarnings("rawtypes")
        private  InetAddress getLocalHostLANAddress() throws UnknownHostException {
            try {
                InetAddress candidateAddress = null;
                // 遍歷所有的網路介面
                for (Enumeration ifaces = NetworkInterface.getNetworkInterfaces(); ifaces.hasMoreElements();) {
                    NetworkInterface iface = (NetworkInterface) ifaces.nextElement();
                    // 在所有的介面下再遍歷IP
 

                    for (Enumeration inetAddrs = iface.getInetAddresses(); inetAddrs.hasMoreElements();) {
                        InetAddress inetAddr = (InetAddress) inetAddrs.nextElement();
                        if (!inetAddr.isLoopbackAddress()) {// 排除loopback型別地址
                            if
 
 (inetAddr.isSiteLocalAddress()) {
                                // 如果是site-local地址，就是它了
                                return inetAddr;
                            } else if (candidateAddress == null) {
                                // site-local型別的地址未被發現，先記錄候選地址
                                candidateAddress = inetAddr;
                            }
                        }
                    }
                }
                if
 
 (candidateAddress != null) {
                    return candidateAddress;
                }
                // 如果沒有發現 non-loopback地址.只能用最次選的方案
                InetAddress jdkSuppliedAddress = InetAddress.getLocalHost();
                if (jdkSuppliedAddress == null) {
                    throw new UnknownHostException("The JDK InetAddress.getLocalHost() method unexpectedly returned null.");
                }
                return jdkSuppliedAddress;
            } catch (Exception e) {
                UnknownHostException unknownHostException = new UnknownHostException(
                        "Failed to determine LAN address: " + e);
                unknownHostException.initCause(e);
                throw unknownHostException;
            }
        }