Android 判断网络是否可用以及网络类型（WIFI,2G,3G,4G）

Android中通过系统方法判断网络状态以及网络类型

public class NetState {

    /**
     * Unknown network class
     */
    public static final int NETWORK_CLASS_UNKNOWN = 0;

    /**
     * wifi net work
     */
    public static final int NETWORK_WIFI = 1;

    /**
     * "2G" networks
     */
    public static final int NETWORK_CLASS_2_G = 2;

    /**
     * "3G" networks
     */
    public static final int NETWORK_CLASS_3_G = 3;

    /**
     * "4G" networks
     */
    public static final int NETWORK_CLASS_4_G = 4;


    /**
     * @return 是否有活动的网络连接
     */
    public static boolean hasNetWorkConnection(Context context) {
        //获取连接活动管理器
        final ConnectivityManager connectivityManager = (ConnectivityManager) context.
                getSystemService(Context.CONNECTIVITY_SERVICE);
        //获取链接网络信息
        final NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();

        return (networkInfo != null && networkInfo.isAvailable());

    }


    public static int getNetWorkClass(Context context) {
        TelephonyManager telephonyManager = (TelephonyManager) context.getSystemService(Context.TELEPHONY_SERVICE);

        switch (telephonyManager.getNetworkType()) {
            case TelephonyManager.NETWORK_TYPE_GPRS:
            case TelephonyManager.NETWORK_TYPE_EDGE:
            case TelephonyManager.NETWORK_TYPE_CDMA:
            case TelephonyManager.NETWORK_TYPE_1xRTT:
            case TelephonyManager.NETWORK_TYPE_IDEN:
                return NETWORK_CLASS_2_G;

            case TelephonyManager.NETWORK_TYPE_UMTS:
            case TelephonyManager.NETWORK_TYPE_EVDO_0:
            case TelephonyManager.NETWORK_TYPE_EVDO_A:
            case TelephonyManager.NETWORK_TYPE_HSDPA:
            case TelephonyManager.NETWORK_TYPE_HSUPA:
            case TelephonyManager.NETWORK_TYPE_HSPA:
            case TelephonyManager.NETWORK_TYPE_EVDO_B:
            case TelephonyManager.NETWORK_TYPE_EHRPD:
            case TelephonyManager.NETWORK_TYPE_HSPAP:
                return NETWORK_CLASS_3_G;

            case TelephonyManager.NETWORK_TYPE_LTE:
                return NETWORK_CLASS_4_G;

            default:
                return NETWORK_CLASS_UNKNOWN;
        }
    }


    public static int getNetWorkStatus(Context context) {
        int netWorkType = NETWORK_CLASS_UNKNOWN;

        ConnectivityManager connectivityManager = (ConnectivityManager) context
                .getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();

        if (networkInfo != null && networkInfo.isConnected()) {
            int type = networkInfo.getType();

            if (type == ConnectivityManager.TYPE_WIFI) {
                netWorkType = NETWORK_WIFI;
            } else if (type == ConnectivityManager.TYPE_MOBILE) {
                netWorkType = getNetWorkClass(context);
            }
        }

        return netWorkType;
    }
}

使用上面的方法可以检测大部分情况下的网络变化，但是在做硬件开发的时候会遇到这种情况，就是Android平板在插上网线之后，网线另一端连通的是路由器。路由器并没有网络，但是路由器到Android平板那一段是连通的，会导致网络判断为有网络。
所以在这种情况下就需要使用特殊的情况去判断网络到底是否连通，比如可以ping服务器来判断网络连接情况。或者检测自己的长连接来做判断。

public static final boolean ping() {

        String result = null;
        try {
            // ping 的地址，可以换成任何一种可靠的外网 
            String ip = "www.baidu.com";
            // ping网址3次 
            Process p = Runtime.getRuntime().exec("ping -c 3 -w 100 " + ip);
            // 读取ping的内容，可以不加 
            InputStream input = p.getInputStream();
            BufferedReader in = new BufferedReader(new InputStreamReader(input));
            StringBuffer stringBuffer = new StringBuffer();
            String content = "";
            while ((content = in.readLine()) != null) {
                stringBuffer.append(content);
            }
            Log.d("------ping-----", "result content : " + stringBuffer.toString());
            // ping的状态 
            int status = p.waitFor();
            if (status == 0) {
                result = "success";
                return true;
            } else {
                result = "failed";
            }
        } catch (IOException e) {
            result = "IOException";
        } catch (InterruptedException e) {
            result = "InterruptedException";
        } finally {
            Log.d("----result---", "result = " + result);
        }
        return false;
    }

最后附上一个简易的轮询方法检测网络状态

    /**
     * 定时轮询柜门状态
     */
    public void executeCheckNetwork() {
        executorCheckNetwork = Executors.newScheduledThreadPool(1);
        executorCheckNetwork.scheduleWithFixedDelay(
                new CheckNetworkServer(),
                0,
                1,
                TimeUnit.SECONDS);
    }


  /**
     * 轮询网络状态
     */
    class CheckNetworkServer implements Runnable {
        @Override
        public void run() {
            final boolean isConnect = NetState.hasNetWorkConnection(instance);
            final int networkStatus = NetState.getNetWorkStatus(instance);
            runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    //判断网络状态
                    if (!isConnect) {
                        ivWlan.setImageDrawable(getResources().getDrawable(R.mipmap.icon_wifi_network_unline));
                        return;
                    }

                    switch (networkStatus) {
                        case NetState.NETWORK_WIFI:
                            ivWlan.setImageDrawable(getResources().getDrawable(R.mipmap.icon_network_wifi));
                            break;
                        case NetState.NETWORK_CLASS_2_G:
                            ivWlan.setImageDrawable(getResources().getDrawable(R.mipmap.icon_network_2g));
                            break;
                        case NetState.NETWORK_CLASS_3_G:
                            ivWlan.setImageDrawable(getResources().getDrawable(R.mipmap.icon_network_3g));
                            break;
                        case NetState.NETWORK_CLASS_4_G:
                            ivWlan.setImageDrawable(getResources().getDrawable(R.mipmap.icon_network_4g));
                            break;
                        default:
                            ivWlan.setImageDrawable(getResources().getDrawable(R.mipmap.icon_network_wlan));
                            break;
                    }
                }
            });

        }
    }