轮询 GMail 收件箱以获取来自独立应用程序的传入邮件的正确方法

Right way to poll GMail inbox for incoming mail from stand-alone application(轮询 GMail 收件箱以获取来自独立应用程序的传入邮件的正确方法)

问题描述

我正在尝试轮询 GMail 收件箱中的传入邮件.这是我所拥有的:

I am trying to poll GMail inbox for incoming mail. Here is what I have:

import java.util.Properties;

import javax.mail.Authenticator;
import javax.mail.Folder;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.event.MessageCountEvent;
import javax.mail.event.MessageCountListener;

import com.sun.mail.imap.IMAPFolder;
import com.sun.mail.imap.IMAPStore;

public class GmailIncomingTest {

    public static void main(String[] args) {
        try {
            String username = "my.user@gmail.com";
            String password = "mypassword";

            Properties properties = new Properties();
            properties.put("mail.smtp.auth", "true");
            properties.put("mail.smtp.host", "smtp.gmail.com");
            properties.put("mail.smtp.port", "587");

            Session session = Session.getDefaultInstance(properties, new Authenticator() {

                protected PasswordAuthentication getPasswordAuthentication() {
                    return new PasswordAuthentication(username, password);
                }
            });

            IMAPStore store = (IMAPStore) session.getStore("imaps");
            store.connect("smtp.gmail.com", username, password);

            IMAPFolder inbox = (IMAPFolder) store.getFolder("inbox");
            inbox.open(Folder.READ_ONLY);

            inbox.addMessageCountListener(new MessageCountListener() {

                @Override
                public void messagesRemoved(MessageCountEvent event) {

                }

                @Override
                public void messagesAdded(MessageCountEvent event) {
                    Message[] messages = event.getMessages();

                    for (Message message : messages) {
                        try {
                            System.out.println("Mail Subject:- " + message.getSubject());
                        } catch (MessagingException e) {
                            e.printStackTrace();
                        }
                    }
                }
            });

            new Thread(new Runnable() {
                private static final long KEEP_ALIVE_FREQ = 10000;

                @Override
                public void run() {
                    while (!Thread.interrupted()) {
                        try {
                            inbox.idle();
                            Thread.sleep(KEEP_ALIVE_FREQ);                                  
                        } catch (InterruptedException e) {
                        } catch (MessagingException e) {
                        }
                    }
                }
            }).start();                 
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

我想知道这是否是正确的方法，或者是否有其他更好的方法.

I would like to know if this is a right way to do this or if there is any other better way.

推荐答案

只要您的服务器支持 IDLE(gmail 将)并且您只希望收到有关新邮件的通知(因为程序正在运行)，那么下面的程序应该满足您的需求.如果服务器不支持 IDLE 和/或旧消息是相关的(或其他事件，如文件夹重命名等)，那么您需要修改代码.在这里查看一些提示:https://github.com/salyh/elasticsearch-imap/blob/master/src/main/java/de/saly/elasticsearch/importer/imap/mailsource/ParallelPollingIMAPMailSource.java

As long your server supports IDLE (gmail will) and you want only notified about new mails (since programm is running) than the below programm should fit your needs. If server does not support IDLE and/or older message are relevant (or other events like folder rename etc) then you need to modify the code. Have a look here for some hints: https://github.com/salyh/elasticsearch-imap/blob/master/src/main/java/de/saly/elasticsearch/importer/imap/mailsource/ParallelPollingIMAPMailSource.java

import java.util.Properties;

import javax.mail.Folder;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Session;
import javax.mail.Store;
import javax.mail.event.MessageCountAdapter;
import javax.mail.event.MessageCountEvent;

import com.sun.mail.imap.IMAPFolder;
import com.sun.mail.imap.IMAPStore;

public class GmailIncomingTest {

    private static final String username = "xxx@gmail.com";
    private static final String password = "passwd";

    public static void main(String[] args) {

        Properties properties = new Properties();
        // properties.put("mail.debug", "true");
        properties.put("mail.store.protocol", "imaps");
        properties.put("mail.imaps.host", "imap.gmail.com");
        properties.put("mail.imaps.port", "993");
        properties.put("mail.imaps.timeout", "10000");

        Session session = Session.getInstance(properties); // not
                                                           // getDefaultInstance
        IMAPStore store = null;
        Folder inbox = null;

        try {
            store = (IMAPStore) session.getStore("imaps");
            store.connect(username, password);

            if (!store.hasCapability("IDLE")) {
                throw new RuntimeException("IDLE not supported");
            }

            inbox = (IMAPFolder) store.getFolder("INBOX");
            inbox.addMessageCountListener(new MessageCountAdapter() {

                @Override
                public void messagesAdded(MessageCountEvent event) {
                    Message[] messages = event.getMessages();

                    for (Message message : messages) {
                        try {
                            System.out.println("Mail Subject:- " + message.getSubject());
                        } catch (MessagingException e) {
                            e.printStackTrace();
                        }
                    }
                }
            });

            IdleThread idleThread = new IdleThread(inbox);
            idleThread.setDaemon(false);
            idleThread.start();

            idleThread.join();
            // idleThread.kill(); //to terminate from another thread

        } catch (Exception e) {
            e.printStackTrace();
        } finally {

            close(inbox);
            close(store);
        }
    }

    private static class IdleThread extends Thread {
        private final Folder folder;
        private volatile boolean running = true;

        public IdleThread(Folder folder) {
            super();
            this.folder = folder;
        }

        public synchronized void kill() {

            if (!running)
                return;
            this.running = false;
        }

        @Override
        public void run() {
            while (running) {

                try {
                    ensureOpen(folder);
                    System.out.println("enter idle");
                    ((IMAPFolder) folder).idle();
                } catch (Exception e) {
                    // something went wrong
                    // wait and try again
                    e.printStackTrace();
                    try {
                        Thread.sleep(100);
                    } catch (InterruptedException e1) {
                        // ignore
                    }
                }

            }
        }
    }

    public static void close(final Folder folder) {
        try {
            if (folder != null && folder.isOpen()) {
                folder.close(false);
            }
        } catch (final Exception e) {
            // ignore
        }

    }

    public static void close(final Store store) {
        try {
            if (store != null && store.isConnected()) {
                store.close();
            }
        } catch (final Exception e) {
            // ignore
        }

    }

    public static void ensureOpen(final Folder folder) throws MessagingException {

        if (folder != null) {
            Store store = folder.getStore();
            if (store != null && !store.isConnected()) {
                store.connect(username, password);
            }
        } else {
            throw new MessagingException("Unable to open a null folder");
        }

        if (folder.exists() && !folder.isOpen() && (folder.getType() & Folder.HOLDS_MESSAGES) != 0) {
            System.out.println("open folder " + folder.getFullName());
            folder.open(Folder.READ_ONLY);
            if (!folder.isOpen())
                throw new MessagingException("Unable to open folder " + folder.getFullName());
        }

    }
}

这篇关于轮询 GMail 收件箱以获取来自独立应用程序的传入邮件的正确方法的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持编程学习网！