Contexts and Dependency Injection (CDI) in Camel Quarkus

CDI plays a central role in Quarkus and Camel Quarkus offers a first class support for it too.

You may use @Inject, @ConfigProperty and similar annotations e.g. to inject beans and configuration values to your Camel RouteBuilder`s. Here is the `RouteBuilder from our timer-log-cdi example:

import javax.enterprise.context.ApplicationScoped;
import javax.inject.Inject;
import org.apache.camel.builder.RouteBuilder;
import org.eclipse.microprofile.config.inject.ConfigProperty;

@ApplicationScoped (1)
public class TimerRoute extends RouteBuilder {

    @ConfigProperty(name = "timer.period", defaultValue = "1000") (2)
    String period;

    @Inject
    Counter counter;

    @Override
    public void configure() throws Exception {
        fromF("timer:foo?period=%s", period)
                .setBody(exchange -> "Incremented the counter: " + counter.increment())
                .to("log:cdi-example?showExchangePattern=false&showBodyType=false");
    }
}

1 The @ApplicationScoped annotation is required for @Inject and @ConfigProperty to work in a RouteBuilder. Note that the @ApplicationScoped beans are managed by the CDI container and their life cycle is thus a bit more complex than the one of the plain RouteBuilder. In other words, using @ApplicationScoped in RouteBuilder comes with some boot time penalty and you should therefore only annotate your RouteBuilder with @ApplicationScoped when you really need it.

2 The value for the timer.period property is defined in src/main/resources/application.properties of the example project.

Please refer to the Quarkus Dependency Injection guide for more details.

CDI and the Camel Bean component

Refer to a bean by name

To refer to a bean in a route definition by name, just annotate the the bean with @Named("myNamedBean") and @ApplicationScoped (or some other supported scope). The @RegisterForReflection annotation is important for the native mode.

import javax.enterprise.context.ApplicationScoped;
import javax.inject.Named;
import io.quarkus.runtime.annotations.RegisterForReflection;

@ApplicationScoped
@Named("myNamedBean")
@RegisterForReflection
public class NamedBean {
    public String hello(String name) {
        return "Hello " + name + " from the NamedBean";
    }
}

Then you can use the myNamedBean name in a route definition:

import org.apache.camel.builder.RouteBuilder;
public class CamelRoute extends RouteBuilder {
    @Override
    public void configure() {
        from("direct:named")
                .to("bean:namedBean?method=hello");
    }
}