取得mac

/**
     * Tested to work with results from ARP command under Solaris, Linux, MS-Windows
     * Note it does not always return a Mac address, even if the host exists. This represents more of
     * a best 'effort' solution.
     */
    private String getMacAddress ( String host ) throws UnknownHostException, IOException, InterruptedException
    {
        String macAddress = null;
        InetAddress hostAddress = InetAddress.getByName( host );
       
        String resultLine = callArpTool ( hostAddress.getHostAddress() );
       
        if ( resultLine == null )
        {
            return null;
        }
        if ( resultLine.indexOf("\n") > -1 )
        {
            String[] lines = resultLine.split("\n");
            resultLine = lines[lines.length -1];
        }
        if ( resultLine.indexOf("--") > -1 || resultLine.indexOf("unknown host") > -1 )
        {
            return null;
        }
               
        int idx = -1;
        if ( resultLine.indexOf( '-' ) > -1 )
        {
            idx = resultLine.indexOf( '-' ) - 2;
        }
        else if ( resultLine.indexOf( ':' ) > -1 )
        {
            idx = resultLine.indexOf( ':' ) - 2;
        }       
         
        int endIdx = resultLine.length()-1;
        if ( resultLine.indexOf(' ',idx+1) > -1 )
        {
            endIdx = resultLine.indexOf(' ',idx+1);
        }
        macAddress = resultLine.substring(idx,endIdx);
       
        return macAddress;
    }
   
    private String callArpTool ( String ipAddress ) throws IOException, InterruptedException
    {
        String result = null;
        /* samples:
        //solaris
        result = "motako (10.1.12.79) at 0:e:a6:b5:70:80";
        result = "arp: motakox: unknown host";
        //linux
        result = "Address                  HWtype  HWaddress           Flags Mask            Iface\n"+
                 "whyme.xxxxxxxxxxxxxxx.c  ether   00:11:D8:DF:2B:9C   C                     eth2";
        result = "batoo.yyyyyy.org (70.55.60.9) -- no entry";
        //windows
        result = " 56 3:  10.1.12.203           00-11-d8-df-2b-9c     dynamic";
        result = " 2 12:Interface: 10.1.12.134 --- 0x50003";
        */
        
        if ( System.getProperty("os.name").toLowerCase().startsWith("windows") )
        {
            return callArpToolWindows( ipAddress );
        }
 
        return callArpToolDefault( ipAddress );
    }
   
    private String callArpToolWindows ( String ipAddress ) throws IOException, InterruptedException
    {
        String[] cmdArray = null;
       
        cmdArray = new String[] { "ping", ipAddress };
       
        Runtime.getRuntime().exec( cmdArray ).waitFor();
       
        cmdArray = new String[] { "arp", "-a" };
       
        StringBuilder stdOut = new StringBuilder();
        Process proc = Runtime.getRuntime().exec( cmdArray );
        new ProcessOutputHandler(stdOut,proc.getInputStream(),2001);
       
        proc.waitFor();
       
        String[] parts = stdOut.toString().split("\n");
        for ( String part : parts )
        {           
            if ( part.indexOf(ipAddress) > -1 )
            {
                return part;
            }
        }
        return null;
     }
   
    private String callArpToolDefault ( String ipAddress ) throws IOException, InterruptedException
    {
        String[] cmdArray = null;
       
        cmdArray = new String[] { "ping", ipAddress };
       
        Runtime.getRuntime().exec( cmdArray ).waitFor();
       
        cmdArray = new String[] { "arp", ipAddress };
       
        StringBuilder stdOut = new StringBuilder();
        Process proc = Runtime.getRuntime().exec( cmdArray );
        new ProcessOutputHandler(stdOut,proc.getInputStream(),2001);
       
        proc.waitFor();
       
        return stdOut.toString();
     }