[JAVA] Hello World (console app) with Apache Camel + Spring Boot 2
Introduction
Create a console application that outputs "Hello World" every second with the following combination.
- Apache Camel 2.3.0
- Spring Boot 2.1.1
- JDK8
- Eclipse Photon(4.8.0)
- Maven
The REST API edition is as follows.
Hello World with Apache Camel + Spring Boot 2 (REST API)
What is Apache Camel?
I don't think Spring Boot needs explanation, so I will explain only Apache Camel briefly.
Apache Camel is often described as middleware (framework) for integration between systems. Integration between systems has a best practice called Enterprise Integration Patterns, which Camel makes it easy. Writing like this sounds a little difficult, and I feel that the threshold is unnecessarily high. In reality, you can think of it as a framework that makes it easy to "receive a request from another system, perform some processing, and send / store (DB or queue) somewhere." REST / SOAP, database (JDBC, MongoDB, DynamoDB, etc), file, message queue (ActiveMQ, Kafka, RabbitMQ, etc), mail, MQTT, etc. can be linked with various things, and parts to realize it Is called a component. There are nearly 200 components, and you can usually find the one you want to connect to. The "do some processing" part also covers functions such as data conversion, format conversion, routing, and error handling, and is a framework that can be used in any application.
Create a project in Eclipse
First, create a new Maven project. Select "Maven Project" and click "Next".
"Next" without any particular changes.
Select "maven-archetype-quickstart" and click "Next".
Enter the project information and click "Finish".
This completes the project creation.
Modify pom.xml
Modify pom.xml as follows.
pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>mkyz08.sample</groupId>
<artifactId>camel-springboot-test</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>camel-springboot-test</name>
<url>http://maven.apache.org</url>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<java.version>1.8</java.version>
<maven.compiler.target>${java.version}</maven.compiler.target>
<maven.compiler.source>${java.version}</maven.compiler.source>
<camel-version>2.23.0</camel-version>
</properties>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-parent</artifactId>
<version>${camel-version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-stream</artifactId>
</dependency>
<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
Create a program
Create the main program as follows.
Application.java
package mkyz08.example;
import org.apache.camel.spring.boot.CamelSpringBootApplicationController;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ApplicationContext;
@SpringBootApplication
public class Application {
public static void main(String[] args) {
ApplicationContext applicationContext = new SpringApplication(Application.class).run(args);
CamelSpringBootApplicationController applicationController =
applicationContext.getBean(CamelSpringBootApplicationController.class);
applicationController.run();
}
}
The following is a normal Spring Boot application launch.
ApplicationContext applicationContext = new SpringApplication(Application.class).run(args);
The following is the difference from starting a normal Spring Boot application.
You can continue execution as a daemon thread by executing the run method of the CamelSpringBootApplicationController class. If you don't do this, the console app will start and exit.
CamelSpringBootApplicationController applicationController =
applicationContext.getBean(CamelSpringBootApplicationController.class);
applicationController.run();
The configuration file is as follows. By setting "spring.main.web-application-type = none", Tomcat will not start. "Timer.period" is an application setting and is used as a setting value when Hello World is displayed every second.
src/main/resources/application.properties
camel.springboot.name = MyCamelApp
spring.main.web-application-type=none
timer.period = 1000
Finally, create a Camel route. Because of Camel's route definition, Component annotation is added to the class and it inherits RouteBuilder class. Then override the configure method and code the contents of the route.
HelloWorldRoute.java
package mkyz08.example;
import org.apache.camel.builder.RouteBuilder;
import org.springframework.stereotype.Component;
@Component
public class HelloWorldRoute extends RouteBuilder {
@Override
public void configure() throws Exception {
from("timer://exampleTimer?period={{timer.period}}")
.routeId("hello world route")
.setBody(simple("Hello World at ${header.firedTime}"))
.to("stream:out");
}
}
Below is the content of the route
--In "timer: //exampleTimer?period={{timer.period}}", define a timer to be executed every second. --". RouteId (" hello world route ")", which only specifies the route ID --".SetBody (simple (" Hello World at $ {header.firedTime} "))", set Hello World string to BODY of Exchange --The Hello World character string in the Exchange BODY is output to the console with ".to (" stream: out ")".
from("timer://exampleTimer?period={{timer.period}}")
.routeId("hello world route")
.setBody(simple("Hello World at ${header.firedTime}"))
.to("stream:out");
Run the Hello World console application
When you execute the created program, it will be output to the console as shown below.
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v2.1.0.RELEASE)
2018-12-06 14:59:46.472 INFO 17612 --- [ main] mkyz08.example.Application : Starting Application on mky-PC with PID 17612 (C:\pleiades\workspace\camel-springboot-test\target\classes started by mky in C:\pleiades\workspace\camel-springboot-test)
2018-12-06 14:59:46.474 INFO 17612 --- [ main] mkyz08.example.Application : No active profile set, falling back to default profiles: default
2018-12-06 14:59:47.516 INFO 17612 --- [ main] trationDelegate$BeanPostProcessorChecker : Bean 'org.apache.camel.spring.boot.CamelAutoConfiguration' of type [org.apache.camel.spring.boot.CamelAutoConfiguration$$EnhancerBySpringCGLIB$$9ed7a086] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)
2018-12-06 14:59:47.731 INFO 17612 --- [ main] o.a.c.i.converter.DefaultTypeConverter : Type converters loaded (core: 195, classpath: 1)
2018-12-06 14:59:48.080 INFO 17612 --- [ main] o.a.camel.spring.boot.RoutesCollector : Loading additional Camel XML routes from: classpath:camel/*.xml
2018-12-06 14:59:48.080 INFO 17612 --- [ main] o.a.camel.spring.boot.RoutesCollector : Loading additional Camel XML rests from: classpath:camel-rest/*.xml
2018-12-06 14:59:48.086 INFO 17612 --- [ main] o.a.camel.spring.SpringCamelContext : Apache Camel 2.23.0 (CamelContext: MyCamelApp) is starting
2018-12-06 14:59:48.086 INFO 17612 --- [ main] o.a.c.m.ManagedManagementStrategy : JMX is enabled
2018-12-06 14:59:48.274 INFO 17612 --- [ main] o.a.camel.spring.SpringCamelContext : StreamCaching is not in use. If using streams then its recommended to enable stream caching. See more details at http://camel.apache.org/stream-caching.html
2018-12-06 14:59:48.385 INFO 17612 --- [ main] o.a.camel.spring.SpringCamelContext : Route: hello world route started and consuming from: timer://exampleTimer?period=1000
2018-12-06 14:59:48.387 INFO 17612 --- [ main] o.a.camel.spring.SpringCamelContext : Total 1 routes, of which 1 are started
2018-12-06 14:59:48.390 INFO 17612 --- [ main] o.a.camel.spring.SpringCamelContext : Apache Camel 2.23.0 (CamelContext: MyCamelApp) started in 0.302 seconds
2018-12-06 14:59:48.394 INFO 17612 --- [ main] mkyz08.example.Application : Started Application in 2.316 seconds (JVM running for 2.825)
Hello World at Thu Dec 06 14:59:49 JST 2018
Hello World at Thu Dec 06 14:59:50 JST 2018
Hello World at Thu Dec 06 14:59:51 JST 2018
Create an executable jar file
To create an executable jar file, enter "clean install spring-boot: repackage" in the goal in "Execution Configuration" and execute it as shown below.
If the execution is successful, the following log will be output.
[INFO] --- spring-boot-maven-plugin:2.1.1.RELEASE:repackage (default-cli) @ camel-springboot-test ---
[INFO] Replacing main artifact with repackaged archive
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 3.930 s
[INFO] Finished at: 2018-12-06T13:03:00+09:00
[INFO] ------------------------------------------------------------------------
The executable jar file is created in the "target" and directory of the project, and can be executed with the following command.
java -jar camel-springboot-test-0.0.1-SNAPSHOT.jar
reference
-Apache Camel official website Spring Boot
-Apache Camel official website Spring Boot sample
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