Spring multiple imapAdapter - email

Question

I am novice in Spring and I don't like code duplication.
I wrote one ImapAdapter that works fine:
#Component
public class GeneralImapAdapter {
private Logger logger = LoggerFactory.getLogger(getClass());
#Autowired
private EmailReceiverService emailReceiverService;
#Bean
#InboundChannelAdapter(value = "emailChannel", poller = #Poller(fixedDelay = "10000", taskExecutor = "asyncTaskExecutor"))
public MessageSource<javax.mail.Message> mailMessageSource(MailReceiver imapMailReceiver) {
return new MailReceivingMessageSource(imapMailReceiver);
}
#Bean
#Value("imaps://<login>:<pass>#<url>:993/inbox")
public MailReceiver imapMailReceiver(String imapUrl) {
ImapMailReceiver imapMailReceiver = new ImapMailReceiver(imapUrl);
imapMailReceiver.setShouldMarkMessagesAsRead(true);
imapMailReceiver.setShouldDeleteMessages(false);
// other setters here
return imapMailReceiver;
}
#ServiceActivator(inputChannel = "emailChannel", poller = #Poller(fixedDelay = "10000", taskExecutor = "asyncTaskExecutor"))
public void emailMessageSource(javax.mail.Message message) {
emailReceiverService.receive(message);
}
}
But I want about 20 adapters like that, the only difference is imapUrl.
How to do that without code duplication?

Answer 1

Use multiple application contexts, configured with properties.
This sample is an example; it uses XML for its configuration, but the same techniques apply with Java configuration.
If you need them to feed into a common emailReceiverService; make the individual adapter contexts child contexts; see the sample readme for pointers about how to do that.
EDIT:
Here's an example, with the service (and channel) in a shared parent context...
#Configuration
#EnableIntegration
public class MultiImapAdapter {
public static void main(String[] args) throws Exception {
AnnotationConfigApplicationContext parent = new AnnotationConfigApplicationContext(MultiImapAdapter.class);
parent.setId("parent");
String[] urls = { "imap://foo", "imap://bar" };
List<ConfigurableApplicationContext> children = new ArrayList<ConfigurableApplicationContext>();
int n = 0;
for (String url : urls) {
AnnotationConfigApplicationContext child = new AnnotationConfigApplicationContext();
child.setId("child" + ++n);
children.add(child);
child.setParent(parent);
child.register(GeneralImapAdapter.class);
StandardEnvironment env = new StandardEnvironment();
Properties props = new Properties();
// populate properties for this adapter
props.setProperty("imap.url", url);
PropertiesPropertySource pps = new PropertiesPropertySource("imapprops", props);
env.getPropertySources().addLast(pps);
child.setEnvironment(env);
child.refresh();
}
System.out.println("Hit enter to terminate");
System.in.read();
for (ConfigurableApplicationContext child : children) {
child.close();
}
parent.close();
}
#Bean
public MessageChannel emailChannel() {
return new DirectChannel();
}
#Bean
public EmailReceiverService emailReceiverService() {
return new EmailReceiverService();
}
}
and
#Configuration
#EnableIntegration
public class GeneralImapAdapter {
#Bean
public static PropertySourcesPlaceholderConfigurer pspc() {
return new PropertySourcesPlaceholderConfigurer();
}
#Bean
#InboundChannelAdapter(value = "emailChannel", poller = #Poller(fixedDelay = "10000") )
public MessageSource<javax.mail.Message> mailMessageSource(MailReceiver imapMailReceiver) {
return new MailReceivingMessageSource(imapMailReceiver);
}
#Bean
#Value("${imap.url}")
public MailReceiver imapMailReceiver(String imapUrl) {
// ImapMailReceiver imapMailReceiver = new ImapMailReceiver(imapUrl);
// imapMailReceiver.setShouldMarkMessagesAsRead(true);
// imapMailReceiver.setShouldDeleteMessages(false);
// // other setters here
// return imapMailReceiver;
MailReceiver receiver = mock(MailReceiver.class);
Message message = mock(Message.class);
when(message.toString()).thenReturn("Message from " + imapUrl);
Message[] messages = new Message[] {message};
try {
when(receiver.receive()).thenReturn(messages);
}
catch (MessagingException e) {
e.printStackTrace();
}
return receiver;
}
}
and
#MessageEndpoint
public class EmailReceiverService {
#ServiceActivator(inputChannel="emailChannel")
public void handleMessage(javax.mail.Message message) {
System.out.println(message);
}
}
Hope that helps.
Notice that you don't need a poller on the service activator - use a DirectChannel and the service will be invoked on the poller executor thread - no need for another async handoff.