java获取主机IP

最简单的获取ip手段：

 String hostAddress = InetAddress.getLocalHost().getHostAddress();

但是由于它是获取本地host对应的ip，而现在电脑往往存在多个ip、网卡甚至虚拟机，这个方法会存在很多问题

于是方法一：

//返回InetAddress，之后再调用getHostAddress()
 private static InetAddress getLocalHostLANAddress() throws UnknownHostException {
        try {
            InetAddress candidateAddress = null;
            // 遍历所有的网络接口
            for (Enumeration ifaces = NetworkInterface.getNetworkInterfaces(); ifaces.hasMoreElements();) {
                NetworkInterface iface = (NetworkInterface) ifaces.nextElement();
                // 在所有的接口下再遍历IP
                for (Enumeration inetAddrs = iface.getInetAddresses(); inetAddrs.hasMoreElements();) {
                    InetAddress inetAddr = (InetAddress) inetAddrs.nextElement();
                    if (!inetAddr.isLoopbackAddress()) {// 排除loopback类型地址
                        if (inetAddr.isSiteLocalAddress()) {
                            // 如果是site-local地址，就是它了
                            return inetAddr;
                        } else if (candidateAddress == null) {
                            // site-local类型的地址未被发现，先记录候选地址
                            candidateAddress = inetAddr;
                        }
                    }
                }
            }
            if (candidateAddress != null) {
                return candidateAddress;
            }
            // 如果没有发现 non-loopback地址.只能用最次选的方案
            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;
        }
    }

方法二：

//返回ip
public static String getRealIP() {
        try {
            Enumeration allNetInterfaces = NetworkInterface
                    .getNetworkInterfaces();
            while (allNetInterfaces.hasMoreElements()) {
                NetworkInterface netInterface = (NetworkInterface) allNetInterfaces
                        .nextElement();

                // 去除回环接口，子接口，未运行和接口
                if (netInterface.isLoopback() || netInterface.isVirtual()
                        || !netInterface.isUp()) {
                    continue;
                }

                if (!netInterface.getDisplayName().contains("Intel")
                        && !netInterface.getDisplayName().contains("Realtek")) {
                    continue;
                }
                Enumeration addresses = netInterface
                        .getInetAddresses();
                System.out.println(netInterface.getDisplayName());
                while (addresses.hasMoreElements()) {
                    InetAddress ip = addresses.nextElement();
                    if (ip != null) {
                        // ipv4
                        if (ip instanceof Inet4Address) {
                            System.out.println("ipv4 = " + ip.getHostAddress());
                            return ip.getHostAddress();
                        }
                    }
                }
                break;
            }
        } catch (SocketException e) {
            System.err.println("Error when getting host ip address"
                    + e.getMessage());
        }
        return null;
    }

方法三，利用socket的方法：

private static InetAddress getLocalAddressBySocket(Map destHostPorts) {
        if (destHostPorts == null || destHostPorts.size() == 0) {
            return null;
        }

        for (Map.Entry entry : destHostPorts.entrySet()) {
            String host = entry.getKey();
            int port = entry.getValue();
            try {
                Socket socket = new Socket();
                try {
                    SocketAddress addr = new InetSocketAddress(host, port);
                    socket.connect(addr, 1000);
                    return socket.getLocalAddress();
                } finally {
                    try {
                        socket.close();
                    } catch (Throwable e) {}
                }
            } catch (Exception e) {
                LoggerUtil.warn(String.format("Failed to retriving local address by connecting to dest host:port(%s:%s) false, e=%s", host,
                        port, e));
            }
        }
        return null;
    }

获取ip的方法各有特点，具体还要结合实际环境需求，选择合适的过滤方法。