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Chapter 5. 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, for example:
import jakarta.enterprise.context.ApplicationScoped; import jakarta.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
@ApplicationScopedannotation is required for@Injectand@ConfigPropertyto work in aRouteBuilder. Note that the@ApplicationScopedbeans are managed by the CDI container and their life cycle is thus a bit more complex than the one of the plainRouteBuilder. In other words, using@ApplicationScopedinRouteBuildercomes with some boot time penalty and you should therefore only annotate yourRouteBuilderwith@ApplicationScopedwhen you really need it. - 2
- The value for the
timer.periodproperty is defined insrc/main/resources/application.propertiesof the example project.
Refer to the Quarkus Dependency Injection guide for more details.
5.1. Accessing CamelContext
To access CamelContext just inject it into your bean:
import jakarta.inject.Inject;
import jakarta.enterprise.context.ApplicationScoped;
import java.util.stream.Collectors;
import java.util.List;
import org.apache.camel.CamelContext;
@ApplicationScoped
public class MyBean {
@Inject
CamelContext context;
public List<String> listRouteIds() {
return context.getRoutes().stream().map(Route::getId).sorted().collect(Collectors.toList());
}
}5.2. @EndpointInject and @Produce
If you are used to @org.apache.camel.EndpointInject and @org.apache.camel.Produce from plain Camel or from Camel on SpringBoot, you can continue using them on Quarkus too.
The following use cases are supported by org.apache.camel.quarkus:camel-quarkus-core:
import jakarta.enterprise.context.ApplicationScoped;
import org.apache.camel.EndpointInject;
import org.apache.camel.FluentProducerTemplate;
import org.apache.camel.Produce;
import org.apache.camel.ProducerTemplate;
@ApplicationScoped
class MyBean {
@EndpointInject("direct:myDirect1")
ProducerTemplate producerTemplate;
@EndpointInject("direct:myDirect2")
FluentProducerTemplate fluentProducerTemplate;
@EndpointInject("direct:myDirect3")
DirectEndpoint directEndpoint;
@Produce("direct:myDirect4")
ProducerTemplate produceProducer;
@Produce("direct:myDirect5")
FluentProducerTemplate produceProducerFluent;
}
You can use any other Camel producer endpoint URI instead of direct:myDirect*.
@EndpointInject and @Produce are not supported on setter methods - see #2579
The following use case is supported by org.apache.camel.quarkus:camel-quarkus-bean:
import jakarta.enterprise.context.ApplicationScoped;
import org.apache.camel.Produce;
@ApplicationScoped
class MyProduceBean {
public interface ProduceInterface {
String sayHello(String name);
}
@Produce("direct:myDirect6")
ProduceInterface produceInterface;
void doSomething() {
produceInterface.sayHello("Kermit")
}
}5.3. CDI and the Camel Bean component
5.3.1. Refer to a bean by name
To refer to a bean in a route definition by name, just annotate the bean with @Named("myNamedBean") and @ApplicationScoped (or some other supported scope). The @RegisterForReflection annotation is important for the native mode.
import jakarta.enterprise.context.ApplicationScoped;
import jakarta.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")
.bean("myNamedBean", "hello");
/* ... which is an equivalent of the following: */
from("direct:named")
.to("bean:myNamedBean?method=hello");
}
}
As an alternative to @Named, you may also use io.smallrye.common.annotation.Identifier to name and identify a bean.
import jakarta.enterprise.context.ApplicationScoped;
import io.quarkus.runtime.annotations.RegisterForReflection;
import io.smallrye.common.annotation.Identifier;
@ApplicationScoped
@Identifier("myBeanIdentifier")
@RegisterForReflection
public class MyBean {
public String hello(String name) {
return "Hello " + name + " from MyBean";
}
}Then refer to the identifier value within the Camel route:
import org.apache.camel.builder.RouteBuilder;
public class CamelRoute extends RouteBuilder {
@Override
public void configure() {
from("direct:start")
.bean("myBeanIdentifier", "Camel");
}
}We aim at supporting all use cases listed in Bean binding section of Camel documentation. Do not hesitate to file an issue if some bean binding scenario does not work for you.
5.3.2. @Consume
Since Camel Quarkus 2.0.0, the camel-quarkus-bean artifact brings support for @org.apache.camel.Consume - see the Pojo consuming section of Camel documentation.
Declaring a class like the following
import org.apache.camel.Consume;
public class Foo {
@Consume("activemq:cheese")
public void onCheese(String name) {
...
}
}will automatically create the following Camel route
from("activemq:cheese").bean("foo1234", "onCheese")
for you. Note that Camel Quarkus will implicitly add @jakarta.inject.Singleton and jakarta.inject.Named("foo1234") to the bean class, where 1234 is a hash code obtained from the fully qualified class name. If your bean has some CDI scope (such as @ApplicationScoped) or @Named("someName") set already, those will be honored in the auto-created route.
