Spring/Rabbit boilerplate

1 EmailUpdated.java

import lombok.Data;

@Data
public final class EmailUpdated {
    private String accountId;
    private String oldEmail;
    private String newEmail;
    
    public EmailUpdated(String accountId, String oldEmail, String newEmail) {
        this.accountId = accountId;
        this.oldEmail = oldEmail;
        this.newEmail = newEmail;
    }
    
    // for Jackson
    private EmailUpdated() {}
}

2 AccountSettingsController.java

@RequestMapping(path = "/some/path", method = POST)
public ModelAndView updateEmail(@Valid NewEmailForm form) {
    // ...
    // call some account-handling service which ultimately does the following:
    eventsService.fire(new EmailUpdated(accountId, oldEmail, newEmail));
    // ...
}

3 MailChimpSynchronization.java

import org.springframework.amqp.rabbit.annotation.RabbitListener;

@Service
public class MailChimpSynchronization {

    @RabbitListener(queues = RabbitConfig.MAILCHIMP_EMAIL_UPDATED_QUEUE)
    public void emailUpdated(EmailUpdated event) {
        updateMailChimpMember(event.getOldEmail(), event.getNewEmail());
    }
}

4 EventsService.java

@Service
public class EventsService {
    
    @Inject
    private RabbitTemplate rabbitTemplate;

    public void fire(EmailUpdated event) {
        String noRoutingKey = "";
        rabbitTemplate.convertAndSend(RabbitConfig.EMAIL_UPDATED_EXCHANGE, noRoutingKey, event);
    }
    
    // ... lots of other fire(Xxx) methods
}

5 RabbitConfig.java

import org.springframework.amqp.core.*;
import org.springframework.context.annotation.*;

@Configuration
public class RabbitConfig {
    public static final String EMAIL_UPDATED_EXCHANGE = "email.updated.exchange";
    // ... lots of other exchange constants...
   
    public static final String MAILCHIMP_EMAIL_UPDATED_QUEUE = "email.updated.mailchimp.queue";
    // ... lots of other queue constants...
    
    @Bean
    public FanoutExchange emailUpdatedExchange() {
        return new FanoutExchange(EMAIL_UPDATED_EXCHANGE, true, false);
    }
    
    @Bean
    public Binding mailchimpEmailUpdatedBinding() {
        return BindingBuilder.bind(mailchimpEmailUpdatedQueue()).to(emailUpdatedExchange());
    }

    @Bean
    public Queue mailchimpEmailUpdatedQueue() {
        return queueWithDelayedRetry(MAILCHIMP_EMAIL_UPDATED_QUEUE);
    }
    
    @Bean
    public Binding bindMailchimpEmailUpdatedQueueToDeadLetter() {
        return BindingBuilder.bind(mailchimpEmailUpdatedQueue())
            .to(backFromTheDeadExchange())
            .with(mailchimpEmailUpdatedQueue().getName());
    }
    
    // ... lots of other exchanges, queues, and bindings...
    
    // Plus, the following beans are defined only once:
    // deadLetterExchange, retryQueue, deadLetterListener, etc.
}