判断网络是否链接

/**
* 检查是否有网
*/
public boolean isConnecting() {
ConnectivityManager mConnectivity = (ConnectivityManager)context.getSystemService(Context.CONNECTIVITY_SERVICE);
TelephonyManager mTelephony = (TelephonyManager) context.
getSystemService(Context.TELEPHONY_SERVICE);

NetworkInfo info = mConnectivity.getActiveNetworkInfo();

if (info == null || !mConnectivity.getBackgroundDataSetting()) {
return false;
}

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;
}
}