问如何判断网络类型是2G、3G还是4G

EN

        public class CommonUtils {

    /**
     * To get device consuming netowkr type is 2g,3g,4g
     *
     * @param context
     * @return "2g","3g","4g" as a String based on the network type
     */
    public static String getNetworkType(Context context) {
        TelephonyManager mTelephonyManager = (TelephonyManager)
                context.getSystemService(Context.TELEPHONY_SERVICE);
        int networkType = mTelephonyManager.getNetworkType();
        switch (networkType) {
            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 "2g";
            case TelephonyManager.NETWORK_TYPE_UMTS:
            case TelephonyManager.NETWORK_TYPE_EVDO_0:
            case TelephonyManager.NETWORK_TYPE_EVDO_A:
                /**
                 From this link https://en.wikipedia.org/wiki/Evolution-Data_Optimized ..NETWORK_TYPE_EVDO_0 & NETWORK_TYPE_EVDO_A
                 EV-DO is an evolution of the CDMA2000 (IS-2000) standard that supports high data rates.

                 Where CDMA2000 https://en.wikipedia.org/wiki/CDMA2000 .CDMA2000 is a family of 3G[1] mobile technology standards for sending voice,
                 data, and signaling data between mobile phones and cell sites.
                 */
            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:
                //Log.d("Type", "3g");
                //For 3g HSDPA , HSPAP(HSPA+) are main  networktype which are under 3g Network
                //But from other constants also it will 3g like HSPA,HSDPA etc which are in 3g case.
                //Some cases are added after  testing(real) in device with 3g enable data
                //and speed also matters to decide 3g network type
                //https://en.wikipedia.org/wiki/4G#Data_rate_comparison
                return "3g";
            case TelephonyManager.NETWORK_TYPE_LTE:
                //No specification for the 4g but from wiki
                //I found(LTE (Long-Term Evolution, commonly marketed as 4G LTE))
                //https://en.wikipedia.org/wiki/LTE_(telecommunication)
                return "4g";
            default:
                return "Notfound";
        }
    }

    /**
     * To check device has internet
     *
     * @param context
     * @return boolean as per status
     */
    public static boolean isNetworkConnected(Context context) {
        ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo netInfo = cm.getActiveNetworkInfo();
        return netInfo != null && netInfo.isConnected();
    }
}

int netType = info.getType();
int netSubtype = info.getSubtype();
if (netType == ConnectivityManager.TYPE_WIFI) {
    return info.isConnected();
} else if (netType == ConnectivityManager.TYPE_MOBILE
    && netSubtype == TelephonyManager.NETWORK_TYPE_UMTS
    && !mTelephony.isNetworkRoaming()) {
        return info.isConnected();
} else {
    return false;
}