Question

我对javamail的使用感到困惑。我需要不时从邮件服务器下载最新的电子邮件，但javamail似乎无法在小时，分钟和秒内查询特定邮件，只有一天可用？

（1）我应该扫描所有回复电子邮件，以便在时间间隔内进行额外检查吗？或者我做错了什么？

（2）我是否应该通过receivedDate按升序排列电子邮件，并安全地忽略电子邮件的顶部（假设以前已经检索过）

（3）任何推荐的扫描间隔？如果与邮件客户端比较怎么办？

private void retrieveEmailsWithinDateInterval() throws ParseException, MessagingException{
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
    Calendar c = Calendar.getInstance();
    c.setTime(new Date());
    c.add(Calendar.DATE, 1);

    //Retrieval of email setting
    Date previousDate = sdf.parse("2018-02-13");
    Date tmrDate = new Date(c.getTimeInMillis());
    String imapHost = "***";
    int port = 587;
    String urlNameStr = "***";
    String emailAddr = "***";
    String emailPass = "***";
    String inboxFolderName = "***";

    Properties props           = System.getProperties();

    props.setProperty("mail.imap.host", imapHost);
    props.setProperty("mail.imap.port", Integer.toString(port));
    props.setProperty("mail.store.protocol", "imap");

    Session session = Session.getDefaultInstance(props, null);
    URLName urlName = new URLName(urlNameStr);
    Store   store   = session.getStore(urlName);

    store.connect(imapHost, emailAddr, emailPass);

    ReceivedDateTerm       minDateTerm = new ReceivedDateTerm(ComparisonTerm.GT, previousDate);
    ReceivedDateTerm       maxDateTerm = new ReceivedDateTerm(ComparisonTerm.LT, tmrDate);
    SearchTerm searchTerm = new AndTerm(minDateTerm, maxDateTerm); 

    IMAPFolder inboxFolder = (IMAPFolder) store.getFolder(inboxFolderName);

    if(!inboxFolder.isOpen())
        inboxFolder.open(Folder.READ_ONLY);

    Message[] messagesInbox = inboxFolder.search(searchTerm);

    for (Message msg : messagesInbox){
        //(1) Should I extra check or alternative solution? 
        //Seem it compare date only and ignore hour, minute and second.
        if (msg.getReceivedDate().getTime() <= previousDate.getTime())
            continue;
        //(2) Should I scan through email messages? 
        //Or will all mail server sort in receivedDate, that I can safely ignore top messages or bottom messages?

        processEmailWithinDatetimeInterval(msg);
    }

    if ((inboxFolder != null) && inboxFolder.isOpen()) {
        inboxFolder.close(true);
    }
    if (store != null) {
        store.close();
    }
}

Answer 1

IMAP协议的限制是您只能按天搜索，而不是按时间搜索。

如果您只想在INBOX中找到之前未见过的最新消息，可以keep track of the UID of the last message you've seen然后ask for messages with larger UIDs，例如

Message[] newMessages = ((UIDFolder)folder).getMessagesByUID(lastSeen + 1, UIDFolder.MAXUID);

Javamail IMAP在特定日期时间内检索最新电子邮件

1 个答案: