java队列发送邮件,Java电子邮件发送队列 - 发送尽可能多的邮件的固定线程数

I'm writing a message processing application (email) that I want to have an outgoing queue. The way I've designed this is having a singleton queue class, ThreadedQueueSender, backed by an Executor Service and a BlockingQueue. Additionally, a thread pool of javax.mail.Transport objects is used to obtain and release connections to the outgoing SMTP server.

This class exposes a method, add(MimeMessage), that adds messages to the work queue (BlockingQueue).

At instantiation of the class, the ExecutorService is initialized to a ThreadPoolExecutor with a fixed number of threads, lets say 5. Each thread's run() method is in infinite loop that only exits when it detects interrupt (when ExecutorService.shutdownNow() is called).

This run method uses BlockingQueue.poll() to take messsages from the work queue until no more are available without blocking, then requests a Transport object from the connection pool, opens the connection, sends all the messages its retrieved, closes the connection and returns the Transport object.

This works, but I feel I am not taking full advantage of the ExecutorService by having a fixed number of threads that run for the life of the application. Also, I am managing the work queue myself instead of letting the concurrency frameworks handle it. How would others implement this functionality? Is it better to wrap each incoming message in a Runnable, then execute the sending logic?

Thank you, any comments are appreciated.

Ryan

解决方案

You should create tasks for every piece of work that should be done by your executor service.

For example you could create a callable "MailSendingTask" that holds the MimeMessage and wraps the mail sending. Queue these MailSendingTasks by submitting them to your executor. Now your Executor decides how many threads will be created (Config it by setting lower and upper thread pool bounds)

You only need to create 2 or 3 classes/interfaces

one MailService Interface that provides a simple send(MimeMessage msg) method

one MailServiceImplementation Class that implements MailService and holds a reference to a configured executor

one class MailSenderTask implementing the callable interface that holds a reference to the MimeMessage object and which does the mail sending.

You could even go futher by creating an extra service that manages the mail socket connections which could be used by the MailSenderTask.

If you want to add "cancelation" you should look at the classes Future and FutureTask