使用javamail api从gmail服务器删除电子邮件

Question

import com.sun.mail.pop3.POP3Folder;
import com.sun.mail.pop3.POP3SSLStore;
import javax.mail.Session;
import javax.mail.Flags;
import javax.mail.Message;
import java.util.Date;
import java.text.SimpleDateFormat;
import java.util.StringTokenizer;
import javax.mail.internet.MimeMessage;
import java.io.FileOutputStream;
import java.io.File;
import java.io.ObjectOutputStream;
import java.io.Writer;
import java.net.URL;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.Store;
import javax.mail.Folder;
import java.util.Properties;
import javax.mail.URLName;


/**
 * This class is responsible for deleting e-mails.
 *
 * @author <a href="mailto:fzammetti@omnytex.com">Frank W. Zammetti</a>.
 */public class deletemail {

    private static final String SMTP_HOST_NAME = "smtp.gmail.com";
    private static final int SMTP_HOST_PORT = 465;
    private static final String SMTP_AUTH_USER = "examplemail@gmail.com";
    private static final String SMTP_AUTH_PWD  = "examplepassword";
 private Session session;
    private POP3SSLStore store;
    private String username;
    private String password;
    private POP3Folder folder;
        URLName  url;
    public static void main(String[] args) throws Exception{
       new deletemail().test();
    }

    public void test() throws Exception{
       try{
        Properties pop3props = new Properties();
        //----------------------------------------------
          String SSL_FACTORY = "javax.net.ssl.SSLSocketFactory";
        Properties pop3Props = new Properties();
        pop3Props.setProperty("mail.pop3.socketFactory.class", SSL_FACTORY);
        pop3Props.setProperty("mail.pop3.socketFactory.fallback", "false");
        pop3Props.setProperty("mail.pop3.port", "995");
        pop3Props.setProperty("mail.pop3.socketFactory.port", "995");
        username="examplemail@gmail.com";
        password="examplepassword";
        url = new URLName("pop3", "pop.gmail.com", 995, "", username, password);
        session = Session.getInstance(pop3Props, null);
        store = new POP3SSLStore(session, url);
        store.connect();
        folder = (POP3Folder) store.getFolder("INBOX");
        folder.open(Folder.READ_WRITE);
       Message message[] = folder.getMessages();
         System.out.println(message.length);
    for (int i=0, n=message.length; i<n; i++) {
         message[i].setFlag(Flags.Flag.DELETED, true);
        System.out.println("hello world");

    }
         folder.close(true);
        store.close();
   }
     catch (Exception e) {

      e.printStackTrace();

    }
 finally {
      try {
        if (folder != null) {
          folder.close(true);
        }
        if (store != null) {
          store.close();
        }
      } catch (Exception e) { }

  }
    }
}

let in first the in box contain 10 messages message.length=10 after executing this program message. length is get decresed to 0 but when i open my gmail account messaes are still thereand they are not get deleted from the inbox

Answer 1

The problem is that GMail is not following IMAP convention of deleting emails.

According to https://javaee.github.io/javamail/FAQ#gmaildelete you have to:

1. Label message with flag [Gmail]/Trash ,
2. Navigate to that label and set flag DELETED to true for that email,
3. Close folder (with expunge flag set to true).

Assuming that you have emails in array you have to do something like this:

        Folder trashFolder = this.open("[Gmail]/Trash", true);
        for (Message m : messages) {
            m.getFolder().copyMessages(new Message[]{m}, trashFolder);
        }
        this.close(trashFolder, true);

        trashFolder = this.open("[Gmail]/Trash", true);
        for (Message m : trashFolder.getMessages()) {
            m.setFlag(Flags.Flag.DELETED, true);
        }
        this.close(trashFolder, true);

Answer 2

这个Gmail 帮助页面可能解释了发生了什么。