Spring Boot
Available as of Camel 2.15
Spring Boot component provide auto-configuration for the Apache Camel. Our opinionated auto-configuration of the Camel context auto-detects Camel routes available in the Spring context and registers the key Camel utilities (like producer template, consumer template and the type converter) as beans.
Maven users will need to add the following dependency to their pom.xml
for this component:
<dependency> <groupId>org.apache.camel</groupId> <artifactId>camel-spring-boot</artifactId> <version>${camel.version}</version> <!-- use the same version as your Camel core version --> </dependency>
camel-spring-boot
jar comes with the spring.factories
file, so as soon as you add that dependency into your classpath, Spring Boot will automatically auto-configure the Camel for you.
Auto-configured Camel context
The most important piece of functionality provided by the Camel auto-configuration is CamelContext
instance. Camel auto-configuration creates SpringCamelContext
for your and take care of the proper initialization and shutdown of that context. Created Camel context is also registered in the Spring application context (under camelContext
bean name), so you can access it just as the any other Spring bean.
@Configuration public class MyAppConfig { @Autowired CamelContext camelContext; @Bean MyService myService() { return new DefaultMyService(camelContext); } }
Auto-detecting Camel routes
Camel auto-configuration collects all the RoutesBuilder
instances from the Spring context and automatically injects them into the provided CamelContext
. It means that creating new Camel route with the Spring Boot starter is as simple as adding the @Component
annotated class into your classpath:
@Component public class MyRouter extends RouteBuilder { @Override public void configure() throws Exception { from("jms:invoices").to("file:/invoices"); } }
...or creating new route RoutesBuilder
bean in your @Configuration
class:
@Configuration public class MyRouterConfiguration { @Bean RoutesBuilder myRouter() { return new RouteBuilder() { @Override public void configure() throws Exception { from("jms:invoices").to("file:/invoices"); } }; } }
Camel properties
Spring Boot auto-configuration automatically connect Spring Boot external configuration (like properties placeholders, OS environment variables or system properties) with the Camel properties support. It basically means that any property defined in application.properties
file:
route.from = jms:invoices
...or set via system property...
java -Droute.to=jms:processed.invoices -jar mySpringApp.jar
...can be used as placeholders in Camel route:
@Component public class MyRouter extends RouteBuilder { @Override public void configure() throws Exception { from("{{route.from}}").to("{{route.to}}"); } }
Custom Camel context configuration
If you would like to perform some operations on CamelContext
bean created by Camel auto-configuration, register CamelContextConfiguration
instance in your Spring context:
@Configuration public class MyAppConfig { ... @Bean CamelContextConfiguration contextConfiguration() { return new CamelContextConfiguration() { @Override void beforeApplicationStart(CamelContext context) { // your custom configuration goes here } }; } }
Method CamelContextConfiguration#
beforeApplicationStart(CamelContext)
will be called just before the Spring context is started, so the CamelContext
instance passed to this callback is fully auto-configured. You can add many instances of CamelContextConfiguration
into your Spring context - all of them will be executed.
Disabling JMX
To disable JMX of the auto-configured CamelContext
use camel.springboot.jmxEnabled
property (JMX is enabled by default). For example you could add the following property to your application.properties
file:
camel.springboot.jmxEnabled = false
Auto-configured consumer and producer templates
Camel auto-configuration provides a pre-configured ConsumerTemplate
and ProducerTemplate
instances. You can simply inject them into your Spring-managed beans:
@Component public class InvoiceProcessor { @Autowired private ProducerTemplate producerTemplate; @Autowired private ConsumerTemplate consumerTemplate; public void processNextInvoice() { Invoice invoice = consumerTemplate.receiveBody("jms:invoices", Invoice.class); ... producerTemplate.sendBody("netty-http:http://invoicing.com/received/" + invoice.id()); } }
By default consumer and producer templates comes with the endpoint cache sizes equal to 1000. You can change that values via the following Spring properties:
camel.springboot.consumerTemplateCacheSize = 100 camel.springboot.producerTemplateCacheSize = 200
Auto-configured TypeConverter
Camel auto-configuration registers TypeConverter
instance named typeConverter
in the Spring context.
@Component public class InvoiceProcessor { @Autowired private TypeConverter typeConverter; public long parseInvoiceValue(Invoice invoice) { String invoiceValue = invoice.grossValue(); return typeConverter.convertTo(Long.class, invoiceValue); } }
Spring type conversion API bridge
Spring comes with the powerful type conversion API. Spring API happens not to be much different from the Camel type converter API. As those APIs are so similar, Camel Spring Boot automatically registers bridge converter (SpringTypeConverter
) that delegates to the Spring conversion API. It basically means that out-of-the-box Camel will threat Spring Converters as Camel ones. With this approach you can enjoy both Camel and Spring converters accessed via Camel TypeConverter
API:
@Component public class InvoiceProcessor { @Autowired private TypeConverter typeConverter; public UUID parseInvoiceId(Invoice invoice) { // Using Spring's StringToUUIDConverter UUID id = invoice.typeConverter.convertTo(UUID.class, invoice.getId()); } }
Under the hood Camel Spring Boot delegates conversion to the Spring's ConversionService
instances available in the application context. If no ConversionService
instance is available, Camel Spring Boot auto-configuration will create one for you.
Disabling type conversions features
If you don't want Camel Spring Boot to register type-conversions related features (like TypeConverter
instance or Spring bridge) set the camel.springboot.typeConversion
property to false
.
camel.springboot.typeConversion = false
Fat jars and fat wars
The easiest way to create Camel-aware Spring Boot fat jar/war is to extend the org.apache.camel.spring.boot.F
class...atJarRouter
package com.example; ... // imports @SpringBootApplication public class MyFatJarRouter extends FatJarRouter { @Override public void configure() throws Exception { from("netty-http:http://0.0.0.0:18080"). setBody().simple("ref:helloWorld"); } @Bean String helloWorld() { return "helloWorld"; } }
...and add the following property to your application.properties
file:
spring.main.sources = com.example.MyFatJarRouter
It is also recommended to define your main class explicitly in the Spring Boot Maven plugin configuration:
<plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> <version>${spring-boot.version}</version> <configuration> <mainClass>org.apache.camel.spring.boot.FatJarRouter</mainClass> </configuration> <executions> <execution> <goals> <goal>repackage</goal> </goals> </execution> </executions> </plugin>
In order to turn your fat jar into fat war, add the following class extending org.apache.camel.spring.boot.F
to your project:atWarInitializer
package com.example; ... // imports public class MyFatWarInitializer extends FatWarInitializer { @Override protected Class<? extends FatJarRouter> routerClass() { return MyFatJarRouter.class; } }