Java 获取MAC地址2

class getMac
{
 public String getMacByIPConfig()
 {
  String str = "";
  String macAddress = "";
  try
  {
   Process pp = Runtime.getRuntime().exec("ipconfig /all ");
   InputStreamReader ir = new InputStreamReader(pp.getInputStream());
   LineNumberReader input = new LineNumberReader(ir);
   while((str = input.readLine())!=null)
   {
    if(str.indexOf("Physical Address")!=-1)
    {
     System.out.println(str);
     macAddress = macAddress + ";" + str.substring(str.indexOf(":")+2,str.length());
    }
   }
  }
  catch(IOException ex)
  {
   ex.printStackTrace();
  }
  return macAddress;
 }
}