android 获取网络类型

好用的函数，值得收藏

<pre>

public static String getNetworkClass(Context context) {
    ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo info = cm.getActiveNetworkInfo();
    if(info==null || !info.isConnected())
        return "-"; //not connected
    if(info.getType() == ConnectivityManager.TYPE_WIFI)
        return "WIFI";
    if(info.getType() == ConnectivityManager.TYPE_MOBILE){
        int networkType = info.getSubtype();
        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: //api<8 : replace by 11
                return "2G";
            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: //api<9 : replace by 14
            case TelephonyManager.NETWORK_TYPE_EHRPD:  //api<11 : replace by 12
            case TelephonyManager.NETWORK_TYPE_HSPAP:  //api<13 : replace by 15
                return "3G";
            case TelephonyManager.NETWORK_TYPE_LTE:    //api<11 : replace by 13
                return "4G";
            default:
                return "?";
        }
    }
    return "?";
}

</pre>

另一个方法：http://www.jianshu.com/p/60c5a606347a