Java 獲取 MAC 地址全方案：本地、遠程、ARP 協議與跨平台實現

方案一：本地 MAC（JDK 1.6+ NetworkInterface）

public static String getLocalMac() throws SocketException {
    InetAddress local = InetAddress.getLocalHost();
    NetworkInterface ni = NetworkInterface.getByInetAddress(local);
    byte[] mac = ni.getHardwareAddress();
    StringBuilder sb = new StringBuilder();
    for (int i=0; i0) sb.append("-");
        String s = Integer.toHexString(mac[i] & 0xFF);
        sb.append(s.length()==1 ? "0"+s : s);
    }
    return sb.toString().toUpperCase();
}

方案二：遠程 IP 獲取 MAC（Windows nbtstat）

public static String getRemoteMacWin(String ip) throws IOException {
    Process p = Runtime.getRuntime().exec("nbtstat -A " + ip);
    BufferedReader br = new BufferedReader(new InputStreamReader(p.getInputStream()));
    String line;
    while ((line = br.readLine()) != null) {
        if (line.indexOf("MAC") > 1) {
            return line.substring(line.indexOf("MAC")+9).trim();
        }
    }
    return null;
}

方案三：ARP 協議解析（跨平台，支持外網）

public static String getMacByArp(String ip) throws IOException, InterruptedException {
    // 先 ping 刷新 ARP 緩存
    Runtime.getRuntime().exec("ping " + ip).waitFor();
    // 讀取 ARP 表
    Process p = Runtime.getRuntime().exec("arp -n"); // Linux: arp -a
    BufferedReader br = new BufferedReader(new InputStreamReader(p.getInputStream()));
    String line;
    while ((line = br.readLine()) != null) {
        if (line.contains(ip)) {
            // 正則提取 MAC
            Pattern pat = Pattern.compile("(([0-9A-Fa-f]{2}[:-]){5}[0-9A-Fa-f]{2})");
            Matcher m = pat.matcher(line);
            if (m.find()) return m.group(1).toUpperCase();
        }
    }
    return null;
}

方案四：ipconfig/all 解析（Windows 本地）

public static String getMacByIpconfig() throws IOException {
    Process p = Runtime.getRuntime().exec("cmd.exe /c ipconfig/all");
    BufferedReader br = new BufferedReader(new InputStreamReader(p.getInputStream()));
    String line;
    while ((line = br.readLine()) != null) {
        if (line.indexOf("Physical Address") > 0) {
            return line.substring(line.indexOf("Physical Address")+36).trim();
        }
    }
    return null;
}

綜合工具類：自動選擇最佳方案

public class MacUtil {
    public static String getMac(String ip) {
        String mac = getMacByArp(ip); // 優先 ARP
        if (mac == null) mac = getRemoteMacWin(ip); // Windows 回退
        if (mac == null) mac = getLocalMac(); // 本地回退
        return mac;
    }
    // 內部實現上述四個私有方法...
}

注意事項

• Windows 需管理員權限執行 nbtstat
• Linux arp 輸出格式不同，分隔符為 :
• 防火牆可能阻擋 ICMP（ping）導致 ARP 刷新失敗
• 虛擬網卡、Docker 網卡會干擾本地 MAC 獲取，需按名稱過濾