in java8 how to a define a function with custom code only? - java-8

Question

I want to send two kinds email, and some logic could shared. e.g.
try {
MimeMessage msg = javaMailService.createMimeMessage();
MimeMessageHelper helper = new MimeMessageHelper(msg, true, DEFAULT_ENCODING);
//custom code here ...
} catch (MessagingException e) {
logger.error("build email fail", e);
} catch (Exception e) {
logger.error("send email fail", e);
}
above is common code (e.g. sendEmail(Function customCode)), below is custom code of sending email to foo
logger.info("send count mail to {}", toFoo);
helper.setFrom(sender);
helper.setTo(toFoo);
helper.setSubject("Foo Subject");
String content = generateFooContent(foo); //use fooTemplate.ftl
helper.setText(content, true);
javaMailService.send(msg);
I want to this effect,
Function fooFunc = ()->{logger.info("send count mail to {}", toFoo);
helper.setFrom(sender);
helper.setTo(toFoo);
helper.setSubject("Foo");
String content = generateFooContent(foo);
helper.setText(content, true);
javaMailService.send(msg);}
then call sendEmail method,
sendEmail(fooFunc);
If I want to send bar message,
Function barFunc = ()->{...} //cunstom code here
sendEmail(barFunc);
In java8 could achieve this？ if could how?

Answer 1

Your "Function" has a signature:
void doStuff(MimeMessageHelper helper)
We already have one of these - it's called a Consumer<MimeMessageHelper>.
So:
final Consumer<MimeMessageHelper> messageCreator = ...
try {
MimeMessage msg = javaMailService.createMimeMessage();
MimeMessageHelper helper = new MimeMessageHelper(msg, true, DEFAULT_ENCODING);
messageCreator.accept(helper);
javaMailService.send(msg);
} catch (MessagingException e) {
logger.error("build email fail", e);
} catch (Exception e) {
logger.error("send email fail", e);
}
Now, to define your sender simply use:
BiConsumer<MimeMessageHelper> fooFunc = helper -> {
logger.info("send count mail to {}", toFoo);
helper.setFrom(sender);
helper.setTo(toFoo);
helper.setSubject("Foo");
String content = generateFooContent(foo);
helper.setText(content, true);
}
P.S. please note my formatting.

Answer 2

Thanks #Boris the Spider， it do works, see below
private void sendFooHtmlMessage(List<Foo> body) {
BiConsumer<MimeMessage,MimeMessageHelper> fooFunc = (msg,helper) -> {
logger.info("send foo mail to {}", toFoo);
try {
helper.setTo(toFoo);
helper.setSubject("Foo Subject");
String content = generateFooContent(body);
helper.setText(content, true);
javaMailService.send(msg);
} catch (Exception e) {
}
};
sendMessage(fooFunc);
}
private void sendMessage(BiConsumer<MimeMessage,MimeMessageHelper> consumer) {
try {
final MimeMessage msg = javaMailService.createMimeMessage();
final MimeMessageHelper helper = new MimeMessageHelper(msg, true, DEFAULT_ENCODING);
helper.setFrom(sender);
consumer.accept(msg, helper);
} catch (MessagingException e) {
logger.error("build email failed", e);
} catch (Exception e) {
logger.error("send email failed", e);
}
}
but still lack something, see above code I have to catch exception in fooFunc, actually I want to throw it because in common sendMesage will catch these exception.
So I adopt another way， see below
public interface SendMessageAction {
void action(MimeMessage msg, MimeMessageHelper helper) throws MessagingException;
}
private void sendMessage(SendMessageAction action) {
//...
}
private void sendFooHtmlMessage(List<Foo> body) {
SendMessageAction fooAction = (msg, helper) -> {
logger.info("send foo mail to {}", toFoo);
//...
};
sendMessage(fooAction);
}