JSP经过udp得到客服端MAC地址

 在网上看到的，感受挺实用的就转过来。

package com.sun.servlet;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
/**
 * 主机A向主机B发送“UDP－NetBIOS－NS”询问包，即向主机B的137端口，发Query包来询问主机B的NetBIOS Names信息。
 * 其次，主机B接收到“UDP－NetBIOS－NS”询问包，假设主机B正确安装了NetBIOS服务........... 并且137端口开放，则主机B会向主机A发送一个“UDP－NetBIOS－NS”应答包，即发Answer包给主机A。
 * 并利用UDP(NetBIOS Name Service)来快速获取远程主机MAC地址的方法
 *
 * @author WINDY
 */
public class UdpGetClientMacAddr {
    private String sRemoteAddr;
    private int iRemotePort=137;
    private byte[] buffer = new byte[1024];
    private DatagramSocket ds=null;

    public UdpGetClientMacAddr(String strAddr) throws Exception{
        sRemoteAddr = strAddr;
        ds = new DatagramSocket();
    }

    protected final DatagramPacket send(final byte[] bytes) throws IOException {
        DatagramPacket dp = new DatagramPacket(bytes,bytes.length,InetAddress.getByName(sRemoteAddr),iRemotePort);
        ds.send(dp);
        return dp;
    }

    protected final DatagramPacket receive() throws Exception {
        DatagramPacket dp = new DatagramPacket(buffer,buffer.length);
        ds.receive(dp);
        return dp;
    }
    protected byte[] GetQueryCmd() throws Exception {
        byte[] t_ns = new byte[50];
        t_ns[0] = 0x00;
        t_ns[1] = 0x00;
        t_ns[2] = 0x00;
        t_ns[3] = 0x10;
        t_ns[4] = 0x00;
        t_ns[5] = 0x01;
        t_ns[6] = 0x00;
        t_ns[7] = 0x00;
        t_ns[8] = 0x00;
        t_ns[9] = 0x00;
        t_ns[10] = 0x00;
        t_ns[11] = 0x00;
        t_ns[12] = 0x20;
        t_ns[13] = 0x43;
        t_ns[14] = 0x4B;

        for(int i = 15; i < 45; i++){
            t_ns[i] = 0x41;
        }
        t_ns[45] = 0x00;
        t_ns[46] = 0x00;
        t_ns[47] = 0x21;
        t_ns[48] = 0x00;
        t_ns[49] = 0x01;
        return t_ns;
    }
    protected final String GetMacAddr(byte[] brevdata) throws Exception {
        // 获取计算机名
        int i = brevdata[56] * 18 + 56;
        String sAddr="";
        StringBuffer sb = new StringBuffer(17);
        // 先从第56字节位置，读出Number Of Names（NetBIOS名字的个数，其中每一个NetBIOS Names Info部分占18个字节）
        // 而后可计算出“Unit ID”字段的位置＝56＋Number Of Names×18，最后从该位置起连续读取6个字节，就是目的主机的MAC地址。
        for(int j = 1; j < 7;j++)
        {
            sAddr = Integer.toHexString(0xFF & brevdata[i+j]);
            if(sAddr.length() < 2)
            {
                sb.append(0);
            }
            sb.append(sAddr.toUpperCase());
            if(j < 6) sb.append(':');
        }
        return sb.toString();
    }

    public final void close() {
        try
        {
            ds.close();
        }
        catch (Exception ex){
            ex.printStackTrace();
        }
    }

    public final String GetRemoteMacAddr() throws Exception {
        byte[] bqcmd = GetQueryCmd();
        send(bqcmd);
        DatagramPacket dp = receive();
        String smac = GetMacAddr(dp.getData());
        close();

        return smac;
    }
}

JSP文件：

<span style="color:#000000;"><%
                String smac = "";
                String sip = request.getHeader("x-forwarded-for");
                if (sip == null || sip.length() == 0
                        || "unknown".equalsIgnoreCase(sip)) {
                    sip = request.getHeader("Proxy-Client-IP");
                }
                if (sip == null || sip.length() == 0
                        || "unknown".equalsIgnoreCase(sip)) {
                    sip = request.getHeader("WL-Proxy-Client-IP");
                }
                if (sip == null || sip.length() == 0
                        || "unknown".equalsIgnoreCase(sip)) {
                    sip = request.getRemoteAddr();
                }
                UdpGetClientMacAddr umac = new UdpGetClientMacAddr(sip);
                smac = umac.GetRemoteMacAddr();
                session.setAttribute("smac", smac);
            %></span>