Java Get MAC Address

The following is the source code:

package test; importjava.io.bufferedreader;importjava.io.file;importjava.io.ioexception;  importjava.io.inputstream; importjava.io.inputstreamreader; importjava.io.linenumberreader;  Importjava.util.date; publicclass test {    public static string  getmacaddresswithcmd ()  {    String mac = null;     try {        date date1 = new date ();         process pro = runtime.getruntime (). EXEC (" Cmd.exe /c ipconfig/all ");         inputstream is =  pro.getinputstream ();        bufferedreader br =  New bufferedreader (New inputstreamreader (is,              "UTF-8"); &nBsp;       string message = br.readline ();         int index = -1;         while  (message != null)  {        if  (index  = message.indexof ("physical address"))  > 0)  {             mac = message.substring (index + 36). Trim ();             break;         }        message = br.readline ();     }        br.close ();         pro.destroy ();        date date2 =  New date ();   &Nbsp;     system.out.println ("Getmacaddresswithcmd:"  +  (Date2.gettime ()- Date1.gettime ())  +  "MS");    } catch  (ioexception e)  {         system.out.println ("Can ' t get mac address!");         return null;    }         return mac;    }    public  Static string getmacaddresswithip (STRING&NBSP;IP)  {         String str =  "";         string macaddress  =  "";        try {             date date1 = new date ();             string scancmd =  "c:\\windows\\system32\\nbtstat.exe -a ";// 32-bit system             File file = new  File ("C:\\windows\\syswow64");            //  64-bit Systems             if  (file.exists ())  {             scancmd =  "c:\\windows\\ sysnative\\nbtstat.exe -a  ";        }         process p = runtime.getruntime (). exec (SCANCMD&NBSP;+&NBSP;IP);         InputStreamReader ir = new  InputStreamReader (P.getinputstream ());        linenumberreader  Input = new linenumberreader (IR);        for  (int i = 1; i < 100 ;  i++)  {            str =  Input.readline ();            if  (str !=  null)  {                 if  (Str.indexof ("mac address")  > 1)  {                     macAddress =  Str.substring (                     str.indexof ("Mac address")  + 14, str.length ());                     break;                 }             }    }    date date2 =  new date ();     system.out.println ("Getmacaddresswithip:"  +  ( Date2.gettime ()-date1.gettime ())  +  "MS");    } catch  (IOException  e)  {        e.printstacktrace (System.out);     }        return macaddress;    }     public static void main (String[] args)  {         system.out.println ("Mac address:"  + getmacaddresswithip (" 192.168.0.124 "));         system.out.println (" Mac address: " +  getmacaddresswithcmd ());     }} 

Getmacaddresswithcmd executes faster and getmacaddresswithip much slower.

The role of Sysnative

In fact, the%windir%\sysnative folder does not exist, it is only a 64-bit Windows system provides a redirection mechanism. We already know that 64-bit Windows uses the System32 and SysWoW64 two-piece folders to differentiate between 64-bit and 32-bit system files, and when 32-bit applications try to access the System32 folder, the system automatically transfers it to the SysWoW64 folder. This allows 32-bit applications to run on both 32-bit systems and 64-bit systems (without the need to change the System32 to SysWoW64 for a 64-bit system). So there is a problem, how do 32-bit applications access the real System32 folder, which is the folder where the 64-bit system files are stored? The answer is through the Sysnative folder. This folder does not exist, which is not found in explorer, but when a 32-bit application tries to access the folder, 64-bit Windows redirects it to the true System32 folder, providing a way for 32-bit applications to access the 64-bit system files. Please refer to MSDN for specific details.

Java Get MAC Address