判断网络是否可用：

注意！是判断网络是否可用，但网络可用不代表一定能上外网的！

    public static boolean isNetworkAvailable(Context context) {

        ConnectivityManager manager = (ConnectivityManager) context
                .getApplicationContext().getSystemService(
                        Context.CONNECTIVITY_SERVICE);
        if (manager == null) {
            return false;
        }
        NetworkInfo networkInfo = manager.getActiveNetworkInfo();
        return networkInfo != null && networkInfo.isConnected();
        
    }

在AndroidManifest.xml文件下，添加下面权限：

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>

如果想判断是否能上外网可以ping一下外网的ip地址：

    public static boolean pingIPAddress(String ipAddress) {
        try {
            //-c 1是指ping的次数为1次，-w 3是指超时时间为3s
            Process process = Runtime.getRuntime()
                    .exec("ping -c 1 -w 3 " + ipAddress);
            //status为0表示ping成功
            int status = process.waitFor();
            if (status == 0) {
                return true;
            }
        }catch (InterruptedException | IOException e) {
            e.printStackTrace();
        }
        return false;
    }

比如ping一下qq.com:

pingIPAddress("qq.com");

在AndroidManifest.xml文件下，添加下面权限：

<uses-permission android:name="android.permission.INTERNET"/>

获取IP地址：

	public static String getHostIPAddress() {
        String IPAddress = null;
        try {
            Enumeration nis = NetworkInterface.getNetworkInterfaces();
            while (nis.hasMoreElements()) {
                NetworkInterface ni = (NetworkInterface) nis.nextElement();
                Enumeration<InetAddress> ias = ni.getInetAddresses();
                while (ias.hasMoreElements()) {
                    InetAddress ia = ias.nextElement();
                    if (ia instanceof Inet6Address) {
                        continue;
                    }
                    String hostAddress = ia.getHostAddress();
                    if (!"127.0.0.1".equals(hostAddress)) {
                        IPAddress = hostAddress;
                        break;
                    }
                }
            }
        } catch (SocketException e) {
            e.printStackTrace();
        }
        
        return IPAddress;
    }

在AndroidManifest.xml文件下，添加下面权限：

<uses-permission android:name="android.permission.INTERNET"/>

获取以太网口MAC地址：

    public static String getEthernetMacAddress() {
        BufferedReader reader = null;
        FileReader fr = null;
        String ethernetMacAddress = null;
        try {
            fr = new FileReader("sys/class/net/eth0/address");
            reader = new BufferedReader(fr);
            ethernetMacAddress = reader.readLine();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (reader != null)
                    reader.close();
                if (fr != null)
                    fr.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return ethernetMacAddress;
    }