[Android] get Target MAC Address

最近遇到一個問題，在區網中要連線數台裝置，需要知道MAC Address

做為識別（IP為DHCP派發），網路上查詢，JAVA並沒有提供此種連線

方式取得目地方的MAC Address，所幸網路上有神人分享讀取arp table

的方式，實作上也可行。

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

import android.util.Log;

public class GetMACAddress{
 public String getMacFromArpCache(String ip) {
     if (ip == null)
         return null;
     BufferedReader br = null;
     try {
         br = new BufferedReader(new FileReader("/proc/net/arp"));
         String line;
         while ((line = br.readLine()) != null) {
             String[] splitted = line.split(" +");
             if (splitted != null && splitted.length >= 4 && ip.equals(splitted[0])) {
                 // Basic sanity check
                 String mac = splitted[3];
                 Log.d("go", "mac " +mac  +" ip "+ ip);
                 if (mac.matches("..:..:..:..:..:..")) {
                     return mac;
                 } else {
                     return null;
                 }
             }
         }
     } catch (Exception e) {
         e.printStackTrace();
     } finally {
         try {
             br.close();
         } catch (IOException e) {
             e.printStackTrace();
         }
     }
     return null;
 }
}

參考來源：

http://www.flattermann.net/2011/02/android-howto-find-the-hardware-mac-address-of-a-remote-host/