获取手机当前的联网状态2G/3G/4G/WIFI

记录一个获取手机当前联网状态的方法，可以当作工具直接使用，比较方便。

private String getNetType(Context context) {
String type = "";
ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo info = cm.getActiveNetworkInfo();
if (info == null) {
type = "null";
} else if (info.getType() == ConnectivityManager.TYPE_WIFI) {
type = "wifi";
} else if (info.getType() == ConnectivityManager.TYPE_MOBILE) {
int subType = info.getSubtype();
if (subType == TelephonyManager.NETWORK_TYPE_CDMA || subType == TelephonyManager.NETWORK_TYPE_GPRS
|| subType == TelephonyManager.NETWORK_TYPE_EDGE) {
type = "2g";
} else if (subType == TelephonyManager.NETWORK_TYPE_UMTS || subType == TelephonyManager.NETWORK_TYPE_HSDPA
|| subType == TelephonyManager.NETWORK_TYPE_EVDO_A || subType == TelephonyManager.NETWORK_TYPE_EVDO_0
|| subType == TelephonyManager.NETWORK_TYPE_EVDO_B) {
type = "3g";
} else if (subType == TelephonyManager.NETWORK_TYPE_LTE) {// LTE是3g到4g的过渡，是3.9G的全球标准
type = "4g";
}
}
return type;
}

参考：http://blog.sina.com.cn/s/blog_5da93c8f0102vg21.html