使用pop3通过javamail获取电子邮件的收到日期的问题

Question

我试图通过javamail获取yahoo.de的电子邮件信息.我可以得到主题,从,等等,但我无法收到电子邮件的收到日期.我使用了getReceivedDate方法,它返回null.这是我的代码..任何人都可以帮助我如何通过javamail获取POP3收到的电子邮件的日期？

import java.io.IOException;
import java.util.Properties;
import javax.mail.Flags;
import javax.mail.Folder;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Session;
import javax.mail.Store;

public class FolderFetchPop3 {

    public static void main(String[] args) throws MessagingException, IOException {
        Folder folder = null;
        Store store = null;

        try {
            Properties props = System.getProperties();
            props.setProperty("mail.store.protocol", "pop3");
            Session session = Session.getDefaultInstance(props, null);
            store = session.getStore("pop3");
            store.connect("pop.mail.yahoo.com","username@yahoo.de", "password of emailid");
            folder = store.getFolder("inbox");

            if(!folder.isOpen())
            folder.open(Folder.READ_WRITE);
            Message[] messages = folder.getMessages();
            System.out.println("No of Messages : " + folder.getMessageCount());
            System.out.println("No of Unread Messages : " + folder.getUnreadMessageCount());
            System.out.println(messages.length);
            for (int i=0; i < messages.length;i++) {
                System.out.println("*****************************************************************************");
                System.out.println("MESSAGE " + (i + 1) + ":");
                Message msg =  messages[i];
                //System.out.println(msg.getMessageNumber());
                System.out.println("Subject: " + msg.getSubject());
                System.out.println("From: " + msg.getFrom()[0]);
                System.out.println("To: "+msg.getAllRecipients()[0]);
                System.out.println("Date: "+msg.getReceivedDate());
                System.out.println("Size: "+msg.getSize());
            }
        } finally {
            if (folder != null && folder.isOpen()) { folder.close(true); }
            if (store != null) { store.close(); }
        }
    }
}

Answer 1

查看Java Mail API FAQ:

问:为什么getReceivedDate()在使用POP3时会返回null？
答: POP3协议不提供有关何时收到消息的信息.可以通过查看某些消息标题(例如Received标头)来猜测收到的日期,但这不是很可靠.

因此,为了获得有关收到的日期的一些信息,请检查MimeMessage#getHeader(String name)并尝试获取Received您可以尝试解释的标题.