components/camel-spring-javaconfig/src/main/docs/spring-javaconfig.adoc

[[SpringJavaConfig-SpringJavaConfig]]
== Spring Java Config

Spring started life using XML Config to wire beans
together. However some folks don't like using XML and would rather use
Java code which led to the creation of Guice along with the Spring
JavaConfig project.

You can use either the XML or Java config approaches with Camel; its
your choice really on which you prefer.

[[SpringJavaConfig-UsingSpringJavaConfig]]
=== Using Spring Java Config

To use Spring Java Config in your Camel project the easiest thing to do
is add the following to your pom.xml

[source,xml]
--------------------------------------------------
<dependency>
  <groupId>org.apache.camel</groupId>
  <artifactId>camel-spring-javaconfig</artifactId>
  <version>${camel-version}</version>
</dependency>
--------------------------------------------------

This will then add the dependencies on the Spring JavaConfig library
along with some helper classes for configuring Camel inside Spring.

Note that this library is totally optional; you could just wire Camel
together yourself with Java Config.

[[SpringJavaConfig-Configuration]]
=== Configuration

The most common case of using JavaConfig with Camel would be to create
configuration with defined list of routes to be used by router.

[source,java]
--------------------------------------------------------------------
@Configuration
public class MyRouteConfiguration extends CamelConfiguration {

    @Autowire
    private MyRouteBuilder myRouteBuilder;

    @Autowire
    private MyAnotherRouteBuilder myAnotherRouteBuilder;

    @Override
    public List<RouteBuilder> routes() {
        return Arrays.asList(myRouteBuilder, myAnotherRouteBuilder);
    } 

}
--------------------------------------------------------------------

You can skip the *routes()* definition, and
fall back to the *RouteBuilder* instances located in the Spring context.

[source,java]
--------------------------------------------------------------
@Configuration
@ComponentScan("com.example.routes")
public class MyRouteConfiguration extends CamelConfiguration {
}
--------------------------------------------------------------

[[SpringJavaConfig-Testing]]
=== Testing

You can use the `CamelSpringJUnit4ClassRunner` with
`CamelSpringDelegatingTestContextLoader`. This is the recommended way to
test Java Config and Camel integration.

If you wish to create a collection of *RouteBuilder* instances then
derive from the *CamelConfiguration* helper class and implement the
*routes()* method. Keep in mind that if
you don't override *routes()* method, then *CamelConfiguration* will use
all *RouteBuilder* instances available in the Spring context.

The *@ContextConfiguration* annotation tells the
Spring Testing framework to load the
*ContextConfig* class as the configuration to use. This class derives
from *SingleRouteCamelConfiguration* which is a helper Spring Java
Config class which will configure the CamelContext for us and then
register the RouteBuilder we create.