java 获取本地路由器分配给电脑的IP地址与主机名相关

本人最近做PC端项目,遇到一个ip地址相关通信方面的问题,经过网上资料的一些查询觉得目前此方法相对较好,特在此做个记录,各位路过的大神,如有更好的方法,麻烦留下解答,让小弟借鉴下.
下面进入正题,首先获取到本机的ip地址,比较简单(主要通过cmd指令arp -a拿到当前电脑所有的缓存地址与ip地址所对应表),如下代码

public class GoodWindowsExec {
    @SuppressWarnings("unused")
    public static ArrayList<String> exec(String cmdLine) {
        ArrayList<String>   lines  = new ArrayList<>();
        try {
            String osName = System.getProperty("os.name");
            String[] cmd = new String[3];
            cmd[0] = "cmd.exe";
            cmd[1] = "/C";
            cmd[2] = cmdLine;
            Runtime rt = Runtime.getRuntime();
            Process proc = rt.exec(cmd);
            InputStreamReader ir = new InputStreamReader(proc.getInputStream(),"gbk");
            LineNumberReader input = new LineNumberReader(ir);  
            String line = null;
            while ((line = input.readLine()) != null){
                System.out.println(line);
                lines.add(line);
        }
            // any error???
            int exitVal = proc.waitFor();
            System.out.println("ExitValue: " + exitVal);
        } catch (Throwable t) {
            t.printStackTrace();
        }
        return lines;
    }

    public static void main(String args[]) {
        exec("arp -a");
        Enumeration<NetworkInterface> nets = NetworkInterface
                .getNetworkInterfaces();
        for (NetworkInterface netint : Collections.list(nets))
        if (null != netint.getHardwareAddress()) {
            List<InterfaceAddress> list = netint.getInterfaceAddresses();
            for (InterfaceAddress interfaceAddress : list) {
                String localip=interfaceAddress.getAddress().toString();
                    System.out.println("======="+localip+"===========");
            }
        }
    }

因为我这边的PC客户端需要知道下位机目前的ip地址,而我只知道下位机的主机名,所以我通过得到本机的ip地址,然后遍历ping出局域网下所能Ping通的ip地址然后放入集合中,在遍历出这些地址所对应的主机名匹配,代码如下:

public class IP {
    static public HashMap<String,String> ping; // ping 后的结果集
    static ArrayList<String> actives  = new ArrayList<>();
    public HashMap<String,String>  getPing() { // 用来得到ping后的结果集
        return ping;
    }
    public static long begin;

    // 当前线程的数量, 防止过多线程摧毁电脑
    static int threadCount = 0;

    public IP() {
        ping = new HashMap<String,String> ();
    }

    public void Ping(String ip) throws Exception {
        // 最多30个线程
        while (threadCount > 30)
            Thread.sleep(50);
        threadCount += 1;
        PingIp p = new PingIp(ip);
        p.start();
    }

    public void PingAll() throws Exception {
        // 首先得到本机的IP，得到网段
        String localip =  ListNets.getAllLocalIp().get(0).substring(1,ListNets.getAllLocalIp().get(0).length());
        int k = 0;
        k = localip.lastIndexOf(".");
        String ss = localip.substring(0, k + 1);
        Controller.IP3 = ss;
        for (int i = 1; i <= 255; i++) { // 对所有局域网Ip
            String iip = Controller.IP3 + i;
            Ping(iip);
        }
    }
    class PingIp extends Thread {
        public String ip; // IP

        public PingIp(String ip) {
            this.ip = ip;
        }

        public void run() {
            try {
                Process p = Runtime.getRuntime().exec("ping  " + ip + " -w 300 -n 1");
                InputStreamReader ir = new InputStreamReader(p.getInputStream(),"gbk");
                LineNumberReader input = new LineNumberReader(ir);  
                // 读取结果行
                for (int i = 1; i < 7; i++){
                    input.readLine();
                }
                String line = input.readLine();
                if (line == null ||  line.length() < 17 || line.substring(8, 17).equals("timed out"))
                    ping.put(ip, "None");
                else
                    actives.add(ip);
                // 线程结束
                threadCount -= 1;
            } catch (IOException e) {
            }

        }

    }

    public ArrayList<String> getCrIP() throws Exception {
        PingAll();
        ArrayList<String> crip;
        crip = actives;
        return crip;
    }

public class ConnectThread  extends Thread{
    @Override
    public void run() {
        IP ip = new IP();
        ArrayList<String> lines =new ArrayList<>();
        try {
            lines = ip.getCrIP();
        } catch (Exception e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }
         ArrayList<String>  ips = new ArrayList<>();
         for(String line:lines){
             try {
                String localip =  ListNets.getAllLocalIp().get(0).substring(1,ListNets.getAllLocalIp().get(0).length());
                int k = 0;
                k = localip.lastIndexOf(".");
                String ss = localip.substring(0, k + 1);
                Controller.IP3 = ss;
                if(line.indexOf(Controller.IP3) ==0){
                    String[] s = line.trim().split(" ");
                    ips.add(s[0].trim());
                }
            } catch (SocketException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

         }
         for(int i=0;i<ips.size();i++){
                byte[] address=toIpByte(ips.get(i));
                InetAddress addr;
                try {
                    addr = InetAddress.getByAddress(address);
                    String hostname = addr.getHostName();
                    if(hostname.length()>5 && (hostname.indexOf("下位机主机名")==0)){
                        return;
                    }
                } catch (Exception e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
         }
    }


     private static byte[] toIpByte(String ip) {
            String[] ips=ip.split("\\.");
            byte[] address=new byte[ips.length];
            for (int i=0;i<ips.length;i++){
                address[i]=(byte) Integer.parseInt(ips[i]);
            }
            return address;
        }

     public static void main(String[] args) {
         ConnectThread c = new ConnectThread();
         c.start();
    }

}

这种做法就是在启动PC端的时候,pingip的时候启动速度会略慢,会影响到客户的体验,所以希望一些有更好办法的朋友,给小弟留个言,谢谢了!