`IntegrationFlowAdapter`

The IntegrationFlow interface can be implemented directly and specified as a component for scanning, as the following example shows:

@Component
public class MyFlow implements IntegrationFlow {

    @Override
    public void configure(IntegrationFlowDefinition<?> f) {
        f.<String, String>transform(String::toUpperCase);
    }

}

It is picked up by the IntegrationFlowBeanPostProcessor and correctly parsed and registered in the application context.

For convenience and to gain the benefits of loosely coupled architecture, we provide the IntegrationFlowAdapter base class implementation. It requires a buildFlow() method implementation to produce an IntegrationFlowDefinition by using one of from() methods, as the following example shows:

@Component
public class MyFlowAdapter extends IntegrationFlowAdapter {

    private final AtomicBoolean invoked = new AtomicBoolean();

    public Instant nextExecutionTime(TriggerContext triggerContext) {
        return this.invoked.getAndSet(true) ? null : Instant.now();
    }

    @Override
    protected IntegrationFlowDefinition<?> buildFlow() {
        return fromSupplier(this::messageSource,
                e -> e.poller(p -> p.trigger(this::nextExecutionTime)))
                .split(this)
                .transform(this)
                .aggregate(this)
                .enrichHeaders(Collections.singletonMap("thing1", "THING1"))
                .filter(this)
                .handle(this)
                .channel(c -> c.queue("myFlowAdapterOutput"));
    }

    public String messageSource() {
        return "T,H,I,N,G,2";
    }

    @Splitter
    public String[] split(String payload) {
        return StringUtils.commaDelimitedListToStringArray(payload);
    }

    @Transformer
    public String transform(String payload) {
        return payload.toLowerCase();
    }

    @Aggregator
    public String aggregate(List<String> payloads) {
        return payloads.stream().collect(Collectors.joining());
    }

    @Filter
    public boolean filter(@Header Optional<String> thing1) {
        return thing1.isPresent();
    }

    @ServiceActivator
    public String handle(String payload, @Header String thing1) {
        return payload + ":" + thing1;
    }

}