Class IdleManager

  • public class IdleManager
    extends java.lang.Object
    IdleManager uses the optional IMAP IDLE command (RFC 2177) to watch multiple folders for new messages. IdleManager uses an Executor to execute tasks in separate threads. An Executor is typically provided by an ExecutorService. For example, for a Java SE application:
            ExecutorService es = Executors.newCachedThreadPool();
            final IdleManager idleManager = new IdleManager(session, es);
    For a Java EE 7 application:
            ManagedExecutorService es;
            final IdleManager idleManager = new IdleManager(session, es);
    To watch for new messages in a folder, open the folder, register a listener, and ask the IdleManager to watch the folder:
            Folder folder = store.getFolder("INBOX");
            folder.addMessageCountListener(new MessageCountAdapter() {
                public void messagesAdded(MessageCountEvent ev) {
                    Folder folder = (Folder)ev.getSource();
                    Message[] msgs = ev.getMessages();
                    System.out.println("Folder: " + folder +
                        " got " + msgs.length + " new messages");
                    try {
                        // process new messages
              ; // keep watching for new messages
                    } catch (MessagingException mex) {
                        // handle exception related to the Folder
    This delivers the events for each folder in a separate thread, NOT using the Executor. To deliver all events in a single thread using the Executor, set the following properties for the Session (once), and then add listeners and watch the folder as above.
            // the following should be done once...
            Properties props = session.getProperties();
            props.put("mail.event.scope", "session"); // or "application"
            props.put("mail.event.executor", es);
    Note that, after processing new messages in your listener, or doing any other operations on the folder in any other thread, you need to tell the IdleManager to watch for more new messages. Unless, of course, you close the folder.

    The IdleManager is created with a Session, which it uses only to control debug output. A single IdleManager instance can watch multiple Folders from multiple Stores and multiple Sessions.

    Due to limitations in the Java SE nio support, a SocketChannel must be used instead of a Socket to connect to the server. However, SocketChannels don't support all the features of Sockets, such as connecting through a SOCKS proxy server. SocketChannels also don't support simultaneous read and write, which means that the idle method can't be used if SocketChannels are being used; use this IdleManager instead. To enable support for SocketChannels instead of Sockets, set the mail.imap.usesocketchannels property in the Session used to access the IMAP Folder. (Or mail.imaps.usesocketchannels if you're using the "imaps" protocol.) This will effect all connections in that Session, but you can create another Session without this property set if you need to use the features that are incompatible with SocketChannels.

    NOTE: The IdleManager, and all APIs and properties related to it, should be considered EXPERIMENTAL. They may be changed in the future in ways that are incompatible with applications using the current APIs.

    JavaMail 1.5.2
    • Constructor Summary

      Constructor Description
      IdleManager​(Session session, java.util.concurrent.Executor es)
      Create an IdleManager.
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      boolean isRunning()
      Is the IdleManager currently running? The IdleManager starts running when the Executor schedules its task.
      void stop()
      Stop the IdleManager.
      void watch​(Folder folder)
      Watch the Folder for new messages and other events using the IMAP IDLE command.
      • Methods inherited from class java.lang.Object

        equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Constructor Detail

      • IdleManager

        public IdleManager​(Session session,
                           java.util.concurrent.Executor es)
        Create an IdleManager. The Session is used only to configure debugging output. The Executor is used to create the "select" thread.
        session - the Session containing configuration information
        es - the Executor used to create threads
        Throws: - for Selector failures
    • Method Detail

      • isRunning

        public boolean isRunning()
        Is the IdleManager currently running? The IdleManager starts running when the Executor schedules its task. The IdleManager stops running after its task detects the stop request from the stop method, or if it terminates abnormally due to an unexpected error.
        true if the IdleMaanger is running
        JavaMail 1.5.5
      • watch

        public void watch​(Folder folder)
                   throws MessagingException
        Watch the Folder for new messages and other events using the IMAP IDLE command.
        folder - the folder to watch
        MessagingException - for errors related to the folder
      • stop

        public void stop()
        Stop the IdleManager. The IdleManager can not be restarted.