Java获取机器IP

现象：在进行数据测试时，无意发现某台机器返回的IP不正确，其返回的为127.0.0.1。但其它机器均为正常。

该IP是通过InetAddress.getLocalHost()获取IP地址，查看该方法见其注释为：

 * <p>If there is a security manager, its
 * {@code checkConnect} method is called
 * with the local host name and {@code -1}
 * as its arguments to see if the operation is allowed.
 * If the operation is not allowed, an InetAddress representing
 * the loopback address is returned.

通过跟踪源码发现，是因为没有设置主机的hostname导致的。其解析的逻辑是根据localHostName来获取的，而localHostName在虚拟机里面默认为localhost.localdomain，而localhost.localdomain对应的则默认为127.0.0.1，
更改机器的hostname即可，其更改hostname方法如下：

hostnamectl set-hostname xxx

可以通过以下获取所有的IP（针对多网卡），并且对IP6地址过滤:

public static List<String> getHostAddresses(Boolean filterIp6) {
    List<String> result = new ArrayList<>();
    try {
        Enumeration<NetworkInterface> interfaces = NetworkInterface.getNetworkInterfaces();
        while (interfaces.hasMoreElements()) {
            NetworkInterface networkInterface = interfaces.nextElement();
            if (networkInterface.isLoopback() || networkInterface.isVirtual() || !networkInterface.isUp()) {
                continue;
            }
            Enumeration<InetAddress> address = networkInterface.getInetAddresses();
            while (address.hasMoreElements()) {
                InetAddress add = address.nextElement();
                if (filterIp6 == null || filterIp6.booleanValue() == true) {
                    if (add.getHostAddress().contains(":")) {
                        continue;
                    }
                }
                result.add(add.getHostAddress());
            }
        }
    } catch (SocketException e) {
        e.printStackTrace();
    }
    return result;
}