如何在 java 的单行代码上设置计时器

Question

My requirements is.. I want to set a timer on a single line code in java. If time exceeded then it will throw a timeout exception and it will start to execute that single line code into a different thread.

Here is my code

public Object ShootSMTPMail(String subject,String body,Session session,SMTPServerInfo smtpserverInfo,InternetAddress[] mailAddress_TO) throws Exception
    {
        try
        {
            
Message message = new MimeMessage(session);
            
            message.setFrom(new InternetAddress(smtpserverInfo.SMTPUsername));
            
            message.setRecipients(Message.RecipientType.TO, mailAddress_TO);
            
            message.setSubject(subject);
            
            message.setContent(body, "text/html");
            
            Transport.send(message);// I want to set a timer on this line;
         
            
            return true;
        }
               
        catch(Exception e)
        {
            throw e;
        }
        finally
        {
            
        }
    }

Basically here I am sending emails through Transport.send(), and this statement taking some time to execute, So I want to throw a timeout exception to the font end and want to show the user that it will take some times to execute. and meanwhile I want to execute Transport.send(message); this line in different thread and when I will receive response from Transport.send(message); this execution I will send it to font end. Actually I want make this whole process asynchronous. Please help me..

Answer 1

In java things like that are usually implemented as a service with internal pool of threads.

Something like that:

public class EmailSenderService {

  private ExecutorService threadPool = Executors.new***Pool();

  public Future<?> send(Message message) {
    return threadPool.submit(() -> Transport.send(message));
  }

  public void shutDownService() {
    threadPool.shutdownNow();
    ...
  }
}

Here Transport.send(message) is executing asynchronously in another thread, while the Future instance returned by send() allows the caller to check if the task has finished, to cancel the task, etc.