开发语言：kotlin
开发生态：Android

一、申请权限

在清单AndroidManifest.xml中添加

  <!-- 访问网络状态-->
  <uses-permission android:name="android.permission.INTERNET" />
  <!-- 允许程序访问Wi-Fi网络状态信息-->
  <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />

二、功能实现

    /**
     * 获取MAC地址
     *
     * @param context
     * @return
     */
    fun getMacAddress(context: Context?): String {
        return when {
            Build.VERSION.SDK_INT < Build.VERSION_CODES.M -> {
                getMacDefault(context)
            }
            Build.VERSION.SDK_INT < Build.VERSION_CODES.N -> {
                getMacAddressM()
            }
            else -> {
                getMacFromHardware()
            }
        }
    }

    /**
     * Android  6.0 之前（不包括6.0）
     *
     * @param context
     * @return
     */
    private fun getMacDefault(context: Context?): String {
        var mac = "未获取到设备Mac地址"
        if (context == null) return mac

        val wifi = context.applicationContext.getSystemService(Context.WIFI_SERVICE) as WifiManager
        var info: WifiInfo? = null
        try {
            info = wifi.connectionInfo
        } catch (e: Exception) {
            e.printStackTrace()
        }
        if (info == null) return mac
        mac = info.macAddress

        if (CommonUtil.isNotEmpty(mac)) mac = mac.uppercase(Locale.ENGLISH)

        return mac
    }

    /**
     * Android 6.0（包括） - Android 7.0（不包括）
     *
     * @return
     */
    private fun getMacAddressM(): String {
        var mac = "未获取到设备Mac地址"

        try {
            mac = BufferedReader(FileReader("/sys/class/net/wlan0/address")).readLine()
        } catch (e: IOException) {
            e.printStackTrace()
        }

        return mac
    }

    /**
     * 遍历循环所有的网络接口，找到接口是 wlan0
     *
     * @return
     */
    private fun getMacFromHardware(): String {
        try {
            val all: List<NetworkInterface> =
                Collections.list(NetworkInterface.getNetworkInterfaces())

            for (nif in all) {
                if (!nif.name.equals("wlan0", ignoreCase = true)) continue

                val macBytes = nif.hardwareAddress ?: return ""

                val res1 = StringBuilder()
                for (b in macBytes) {
                    res1.append(String.format("%02X:", b))
                }

                if (res1.isNotEmpty()) {
                    res1.deleteCharAt(res1.length - 1)
                }
                return res1.toString()
            }
        } catch (e: Exception) {
            e.printStackTrace()
        }
        return "未获取到设备Mac地址"
    }

小白的进阶之路，感谢大家的支持！