使用带有POP3协议的javamail检索所有未读电子邮件

Question

我正在尝试访问我的Gmail帐户并从中检索所有未读电子邮件的信息.

我在引用很多链接后编写了我的代码.我给出了一些链接供参考.

使用Java通过GMail帐户发送和接收电子邮件

使用JavaMailAPI接收邮件的Java代码

为了测试我的代码,我创建了一个Gmail帐户.所以我从Gmail收到了4封邮件.我在检查邮件数量后运行我的应用程序.这显示了正确的结果.4封未读邮件.显示所有信息(例如日期,发件人,内容,主题等)

然后我登录到我的新帐户,阅读其中一封电子邮件并重新运行我的应用程序.现在未读消息的计数应为3,但显示"未读消息数:0"

我在这里复制代码.

public class MailReader

{

    Folder inbox;

    // Constructor of the calss.

    public MailReader() {
        System.out.println("Inside MailReader()...");
        final String SSL_FACTORY = "javax.net.ssl.SSLSocketFactory";

        /* Set the mail properties */

        Properties props = System.getProperties();
        // Set manual Properties
        props.setProperty("mail.pop3.socketFactory.class", SSL_FACTORY);
        props.setProperty("mail.pop3.socketFactory.fallback", "false");
        props.setProperty("mail.pop3.port", "995");
        props.setProperty("mail.pop3.socketFactory.port", "995");
        props.put("mail.pop3.host", "pop.gmail.com");

        try

        {

            /* Create the session and get the store for read the mail. */

            Session session = Session.getDefaultInstance(
                    System.getProperties(), null);

            Store store = session.getStore("pop3");

            store.connect("pop.gmail.com", 995, "abc@gmail.com",
                    "paasword");

            /* Mention the folder name which you want to read. */

            // inbox = store.getDefaultFolder();
            // inbox = inbox.getFolder("INBOX");
            inbox = store.getFolder("INBOX");

            /* Open the inbox using store. */

            inbox.open(Folder.READ_ONLY);

            /* Get the messages which is unread in the Inbox */

            Message messages[] = inbox.search(new FlagTerm(new Flags(
                    Flags.Flag.SEEN), false));
            System.out.println("No. of Unread Messages : " + messages.length);

            /* Use a suitable FetchProfile */
            FetchProfile fp = new FetchProfile();
            fp.add(FetchProfile.Item.ENVELOPE);

            fp.add(FetchProfile.Item.CONTENT_INFO);

            inbox.fetch(messages, fp);

            try

            {

                printAllMessages(messages);

                inbox.close(true);
                store.close();

            }

            catch (Exception ex)

            {
                System.out.println("Exception arise at the time of read mail");

                ex.printStackTrace();

            }

        }

        catch (MessagingException e)
        {
            System.out.println("Exception while connecting to server: "
                    + e.getLocalizedMessage());
            e.printStackTrace();
            System.exit(2);
        }

    }

    public void printAllMessages(Message[] msgs) throws Exception
    {
        for (int i = 0; i < msgs.length; i++)
        {

            System.out.println("MESSAGE #" + (i + 1) + ":");

            printEnvelope(msgs[i]);
        }

    }

    public void printEnvelope(Message message) throws Exception

    {

        Address[] a;

        // FROM

        if ((a = message.getFrom()) != null) {
            for (int j = 0; j < a.length; j++) {
                System.out.println("FROM: " + a[j].toString());
            }
        }
        // TO
        if ((a = message.getRecipients(Message.RecipientType.TO)) != null) {
            for (int j = 0; j < a.length; j++) {
                System.out.println("TO: " + a[j].toString());
            }
        }
        String subject = message.getSubject();

        Date receivedDate = message.getReceivedDate();
        Date sentDate = message.getSentDate(); // receivedDate is returning
                                                // null. So used getSentDate()

        String content = message.getContent().toString();
        System.out.println("Subject : " + subject);
        if (receivedDate != null) {
            System.out.println("Received Date : " + receivedDate.toString());
        }
        System.out.println("Sent Date : " + sentDate.toString());
        System.out.println("Content : " + content);

        getContent(message);

    }

    public void getContent(Message msg)

    {
        try {
            String contentType = msg.getContentType();
            System.out.println("Content Type : " + contentType);
            Multipart mp = (Multipart) msg.getContent();
            int count = mp.getCount();
            for (int i = 0; i < count; i++) {
                dumpPart(mp.getBodyPart(i));
            }
        } catch (Exception ex) {
            System.out.println("Exception arise at get Content");
            ex.printStackTrace();
        }
    }

    public void dumpPart(Part p) throws Exception {
        // Dump input stream ..
        InputStream is = p.getInputStream();
        // If "is" is not already buffered, wrap a BufferedInputStream
        // around it.
        if (!(is instanceof BufferedInputStream)) {
            is = new BufferedInputStream(is);
        }
        int c;
        System.out.println("Message : ");
        while ((c = is.read()) != -1) {
            System.out.write(c);
        }
    }

    public static void main(String args[]) {
        new MailReader();
    }
}

我搜索谷歌,但我发现你应该使用Flags.Flag.SEEN来阅读未读的电子邮件.但那在我的案例中没有显示正确的结果.

有人可以指出我可能在做错的地方吗？

如果你需要整个代码,我可以编辑我的帖子.

注意:我编辑了我的问题以包含整个代码而不是我之前发布的代码段.

Answer 1

你的代码应该有效.如果你想要的只是计数,你也可以使用Folder.getUnreadMessageCount()方法.

JavaMail只能告诉你Gmail的用途.也许Gmail认为所有这些消息都已被阅读？也许Gmail网络界面正在标记这些消息？也许您有另一个应用程序监视文件夹中的新邮件？

尝试使用JavaMail读取未读消息,并查看计数是否更改.

您可能会发现打开会话调试很有用,这样您就可以看到Gmail正在返回的实际IMAP响应; 请参阅JavaMail FAQ.

Answer 2

更改inbox.open(Folder.READ_ONLY);为inbox.open(Folder.READ_WRITE); 它将更改您的邮件在收件箱中读取.

Answer 3

您无法使用POP3获取未读邮件.来自JavaMail API:

POP3不支持永久标志(请参阅Folder.getPermanentFlags()).特别是,永远不会为POP3消息设置Flags.Flag.RECENT标志.应用程序可以确定POP3邮箱中的哪些邮件是"新邮件".

您可以使用IMAP协议并使用SEEN标志,如下所示:

public Message[] fetchMessages(String host, String user, String password, boolean read) {
    Properties properties = new Properties();
    properties.put("mail.store.protocol", "imaps");

    Session emailSession = Session.getDefaultInstance(properties);
    Store store = emailSession.getStore();
    store.connect(host, user, password);

    Folder emailFolder = store.getFolder("INBOX");
    // use READ_ONLY if you don't wish the messages
    // to be marked as read after retrieving its content
    emailFolder.open(Folder.READ_WRITE);

    // search for all "unseen" messages
    Flags seen = new Flags(Flags.Flag.SEEN);
    FlagTerm unseenFlagTerm = new FlagTerm(seen, read);
    return emailFolder.search(unseenFlagTerm);
}

另一件需要注意的事情是POP3不处理文件夹.IMAP获取文件夹,POP3只获取收件箱.有关更多信息:如何使用POP3检索gmail子文件夹/标签？