MailResolverService.java 文件源码

/**
 * Chooses the best SMTP server, given a list of MX records.
 * TODO: Actually choose the best record!
 *
 * @param records The MX records.
 * @return An optional, possibly containing an SMTP server address.
 */
private Optional<String> chooseBestRecord(List<Record> records) {
    TreeMultimap<Integer, String> recordMap = decodeRecords(records);

    if(!recordMap.isEmpty()) {
        List<String> topRecords = new LinkedList<>(recordMap.asMap().firstEntry().getValue());

        if(!topRecords.isEmpty()) {
            String record = topRecords.get(0);

            return Optional.of(record.substring(0, record.length() - 1));
        }

    }

    return Optional.empty();
}