Using Annotations

Another way—simple and straightforward—of creating Filters is via Annotations. Here’s an annotated version of NewTradeFilter:

@Component
public class AnnotatedNewTradeFilter {

  @Filter
  public boolean isTradeCancelled(Message<?> message) {
    Trade t = (Trade)message.getPayload();
    return (t.getStatus().equalsIgnoreCase("cancel"));
  }

}

The framework uses the @Filter annotation to annotate the isTradeCancelled method shown above. The following snippet shows how the filter is configured:

<context:component-scan base-package="com.madhusudhan.jsi.flow.filter"/>

<int:filter input-channel="in-channel"
  output-channel="stdout" 
  ref="annotatedNewTradeFilter" >
</int:filter>

The component-scan lets the container scan for annotated beans in the filter package, in this case, the AnnotatedNewTradeFilter class. The annotated method isTradeCancelled is invoked whenever an expected message arrives in the in-channel.