How to write a custom Apache Camel component/endpoint with Spring Boot Java Config

Question

I'm looking for an example/documentation of how to implement a custom Apache Camel component and endpoint with Spring Boot in Java Config. I don't know how I have to annotate the classes, that Could you please provide an example. Without using Spring my (working) code looks like this:

public class MyCustomComponent extends DefaultComponent {
    @Override
    protected Endpoint createEndpoint(String uri, String remaining, Map<String, Object> parameters) throws Exception {
        Endpoint endpoint = new MyCustomEndpoint(uri, this);
        setProperties(endpoint, parameters);
        return endpoint;
    }
}

Registered is the component in resources/META-INF/services/org/apache/camel/component/myscheme with the FQN of the MyCustomComponent class.

public class MyCustomEndpoint extends DefaultEndpoint {

    public MyCustomEndpoint(String uri, MyCustomComponent component) {
        super(uri, component);
    }

    @Override
    public Producer createProducer() throws Exception {
        return new MyCustomProducer(this);
    }

    @Override
    public Consumer createConsumer(Processor processor) throws Exception {
        throw new UnsupportedOperationException("Not implemented yet: MyCustomEndpoint#createConsumer");
    }

    @Override
    public boolean isSingleton() {
        return false;
    }
}

public class MyCustomProducer extends DefaultProducer {

    public MyCustomProducer(Endpoint endpoint) {
        super(endpoint);
    }

    @Override
    public void process(Exchange exchange) throws Exception {
    }
}

Just look at the existing Camel components for an example, also isSingleton should return true. — Claus Ibsen, Feb 03 '20 at 13:55
@Claus Ibsen Thanks for your answer. How can I inject a Spring Bean into the `MyCustomProducer` — Joe, Feb 03 '20 at 14:15

score 3 · Accepted Answer · answered Feb 04 '20 at 08:17

After a lot of search I have found a solution on the base of Spring's BeanFactory. The major obstacle are the circular dependencies (Component -> Endpoint -> Component | Endpoint -> Producer -> Endpoint). At first I have introduced a Spring Configuration class:

@Configuration
public class ComponentConfiguration {

    @Bean("myCustomEndpoint")
    @Scope("prototype")
    public MyCustomEndpoint myCustomEndpoint(String uri, MyCustomComponent component) {
        MyCustomEndpoint endpoint = new MyCustomEndpoint(uri, component);
        return endpoint;
    }

    @Bean("myCustomProducer")
    @Scope("prototype")
    public MyCustomProducer myCustomProducer(MyCustomEndpoint endpoint) {
        return new MyCustomProducer(endpoint);
    }
}

Make the custom Camel component a Spring component with @Componentannotation, so I'm able to inject the BeanFactory to create an instance of the MyCustomEndpoint class on demand (prototype scope).

@org.springframework.stereotype.Component
public class MyCustomComponent extends DefaultComponent {

    @Autowired
    private BeanFactory beanFactory;

    @Override
    protected Endpoint createEndpoint(String uri, String remaining, Map<String, Object> parameters) throws Exception {
        MyCustomEndpoint endpoint = (MyCustomEndpoint) beanFactory.getBean("myCustomEndpoint", uri, this);
        setProperties(endpoint, parameters);
        return endpoint;
    }
}

public class MyCustomEndpoint extends DefaultEndpoint {

    @Autowired
    private BeanFactory beanFactory;

    public MyCustomEndpoint(String uri, MyCustomComponent component) {
        super(uri, component);
    }

    @Override
    public Producer createProducer() throws Exception {
        MyCustomProducer producer = (MyCustomProducer) beanFactory.getBean("myCustomProducer",  this);
        return producer;
    }

    @Override
    public Consumer createConsumer(Processor processor) throws Exception {
        throw new UnsupportedOperationException("Not implemented yet: MyCustomEndpoint#createConsumer");
    }

    @Override
    public boolean isSingleton() {
        return true;
    }
}

public class MyCustomProducer extends DefaultProducer {

    // Now, I am able to inject some other Spring beans
    @Autowired
    private AnotherSpringBean bean;

    public MyCustomProducer(Endpoint endpoint) {
        super(endpoint);
    }

    @Override
    public void process(Exchange exchange) throws Exception {
    }
}

Note that the Camel component MyCustomComponent is already registered in resources/META-INF/services/org/apache/camel/component/myscheme:

class=<fqn-of-MyCustomComponent>

How to write a custom Apache Camel component/endpoint with Spring Boot Java Config

1 Answers1