Apache Camel - Marshalling/Unmarshalling XML/JSON Data Example

We will be unmarshalling, marshalling object of the Employee class.

package com.javainuse.model;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement(name = "employee")
@XmlAccessorType(XmlAccessType.FIELD)
public class Employee {

	private String empName;
	private int empId;

	public String getEmpName() {
		return empName;
	}

	public void setEmpName(String empName) {
		this.empName = empName;
	}

	public int getEmpId() {
		return empId;
	}

	public void setEmpId(int empId) {
		this.empId = empId;
	}
}

Next we create a class to construct a Camel Route. A Route is like a instruction definition to Camel on how to move your messages from one point to another. We are going to create SimpleRouteBuilder.java file that will move files from c://inputFolder to ActiveMQ. Also we will be unmarshalling the input, modify it and then marshal it and send it to the queue. Here we are making use of the JMS component which we will define in the main class later.

package com.javainuse.route;

import javax.xml.bind.JAXBContext;

import org.apache.camel.Exchange;
import org.apache.camel.Processor;
import org.apache.camel.builder.RouteBuilder;
import org.apache.camel.component.jackson.JacksonDataFormat;
import org.apache.camel.converter.jaxb.JaxbDataFormat;

import com.javainuse.model.Employee;
import com.javainuse.processor.MyProcessor;

public class SimpleRouteBuilder extends RouteBuilder {

	@Override
	public void configure() throws Exception {

		// XML Data Format
		JaxbDataFormat xmlDataFormat = new JaxbDataFormat();
		JAXBContext con = JAXBContext.newInstance(Employee.class);
		xmlDataFormat.setContext(con);

		// JSON Data Format
		JacksonDataFormat jsonDataFormat = new JacksonDataFormat(Employee.class);

		from("file:C:/inputFolder").doTry().unmarshal(xmlDataFormat).
		process(new MyProcessor()).marshal(jsonDataFormat).
		to("jms:queue:javainuse").doCatch(Exception.class).process(new Processor() {
					public void process(Exchange exchange) throws Exception {
						Exception cause = exchange.getProperty(Exchange.EXCEPTION_CAUGHT, Exception.class);
						System.out.println(cause);
					}
				});
	}
}

Next we define the Camel Processor class where we will be modifying the unmarshalled object.

package com.javainuse.processor;

import org.apache.camel.Exchange;
import org.apache.camel.Processor;

import com.javainuse.model.Employee;

public class MyProcessor implements Processor {

	public void process(Exchange exchange) throws Exception {
		Employee employee = exchange.getIn().getBody(Employee.class);
		employee.setEmpName("JavaInUse Rocks");
		exchange.getIn().setBody(employee);
	}

}

When Camel is started, it creates a CamelContext object that contains the definition of the Route to be started. Below we create default camel context and load the route created in SimpleRouteBuilder.

package com.javainuse;

import javax.jms.ConnectionFactory;
import org.apache.activemq.ActiveMQConnectionFactory;
import org.apache.camel.CamelContext;
import org.apache.camel.component.jms.JmsComponent;
import org.apache.camel.impl.DefaultCamelContext;

public class MainApp {

    public static void main(String[] args) {
        SimpleRouteBuilder routeBuilder = new SimpleRouteBuilder();
        CamelContext ctx = new DefaultCamelContext();
        
        //configure jms component        
        ConnectionFactory connectionFactory = new ActiveMQConnectionFactory("tcp://0.0.0.0:61616");
        ctx.addComponent("jms", JmsComponent.jmsComponentAutoAcknowledge(connectionFactory));
        
        try {
            ctx.addRoutes(routeBuilder);
            ctx.start();
            Thread.sleep(5 * 60 * 1000);
            ctx.stop();
        }
        catch (Exception e) {
            e.printStackTrace();
        }

    }
}

In C://inputFolder, we have the following employee.txt file-

<employee>
<empName>javainuse</empName>
<empId>1</empId>
</employee>

Now start the ActiveMQ.

camel7_1

and goto http://localhost:8161/admin/queues.jsp, we will see all no active queues on this page.

camel7_2

Next run the MainApp class as a java application and refresh the above activeMQ page. We will see a new queue named javainuse is created and it has json message in it.

camel7_3

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Apache Camel - Marshalling / Unmarshalling XML / JSON Data

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