我自己实现的方法:

/*
 * isOnline - Check if there is a NetworkConnection
 * @return boolean
 */
protected boolean isOnline() {
    ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo netInfo = cm.getActiveNetworkInfo();
    if (netInfo != null && netInfo.isConnected()) {
        return true;
    } else {
        return false;
    }
}

请注意，这是一个 NetworkConnection-Check.如果有 NetworkConnection，它不一定是 InternetConnection.

Be aware of that this is a NetworkConnection-Check. If there is a NetworkConnection it doesn't have to be a InternetConnection.