Transforming CSV to Java Objects using Camel

This tutorial shows how to perform a simple transformation from CSV to Java objects with Camel using as destination a processor or a JMS Queue.

First of all, we will define a class mapping our CSV file.

package com.sample.model;
import java.io.Serializable;

import org.apache.camel.dataformat.bindy.annotation.CsvRecord;
import org.apache.camel.dataformat.bindy.annotation.DataField;

@CsvRecord(separator = ",")
public class User implements Serializable {
    @DataField(pos = 1)
    private String name;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getSurname() {
        return surname;
    }
    public void setSurname(String surname) {
        this.surname = surname;
    }
    @DataField(pos = 2)
    private String surname;
    @Override
    public String toString() {
        return "User [name=" + name + ", surname=" + surname + "]";
    }

}

As you can see, this class is annotated with a @CsvRecord that defines the separator to be used in the CSV file, and the list of fields in the CSV file, with its position. Here is for example a single row CSV we will use:

john,smith

And now the Route Builder class:

import org.apache.camel.CamelContext;
import org.apache.camel.builder.RouteBuilder;
import org.apache.camel.dataformat.bindy.csv.BindyCsvDataFormat;
import org.apache.camel.impl.DefaultCamelContext;
import org.apache.camel.spi.DataFormat;

public class Hello {

    public static void main(String args[]) throws Exception {
        CamelContext context = new DefaultCamelContext();
        final DataFormat bindy = new BindyCsvDataFormat("com.sample.model");
        context.addRoutes(new RouteBuilder() {
            public void configure() {
                from("file:C:\\camel\\in?noop=true").
                unmarshal(bindy)
                .process(new SimpleProcessor());
            }
        });
        context.start();
        Thread.sleep(10000);
        context.stop();
    }

}

As you can see this class, scans for CSV files contained in the folder C:\Camel\In, unmarshalls them using the BindyCsvDataFormat and produces Java Objects of type com.sample.model.User to the SimpleProcessor. Here is a basic implementation for SimpleProcessor which merely prints out the com.sample.model.User:

import java.util.ArrayList;
import java.util.HashMap;
 

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

import com.sample.model.User;

public class SimpleProcessor implements Processor {
    public void process(Exchange exchange) throws Exception {
        ArrayList<HashMap<String, Object>> list = (ArrayList) exchange.getIn()
                .getBody();
        for (HashMap<String, Object> map : list) {
            for (String key : map.keySet()) {

                System.out.println("key : " + key);
                User user = (User) map.get(key);
                System.out.println("value : " + user);
            }
        }

    }
}

The objects are collected by the processor as HashMap of key/values contained in an ArrayList.

Creating a JMS endpoint

Let’s write now a more complex implementation which used an ActiveMQ destination for our objects:

import javax.jms.ConnectionFactory;

import org.apache.activemq.ActiveMQConnection;
import org.apache.activemq.ActiveMQConnectionFactory;
import org.apache.camel.CamelContext;
import org.apache.camel.builder.RouteBuilder;
import org.apache.camel.component.jms.JmsComponent;
import org.apache.camel.dataformat.bindy.csv.BindyCsvDataFormat;
import org.apache.camel.impl.DefaultCamelContext;
import org.apache.camel.spi.DataFormat;
public class HelloJMS {

    public static void main(String args[]) throws Exception {
        CamelContext context = new DefaultCamelContext();
        final DataFormat bindy = new BindyCsvDataFormat("com.sample.model");
       
     
        ConnectionFactory connectionFactory = new ActiveMQConnectionFactory(
                "admin", "admin", ActiveMQConnection.DEFAULT_BROKER_URL);
        context.addComponent("test-jms",
                JmsComponent.jmsComponentAutoAcknowledge(connectionFactory));
       
        context.addRoutes(new RouteBuilder() {
            public void configure() {
                from("file:C:\\camel\\in?noop=true").
                unmarshal(bindy)
                .to("test-jms:queue:testMQDestination");
            }
        });
        context.start();
        Thread.sleep(10000);
        context.stop();
    }

}

This example relies on the default TCP broker URL for ActiveMQ (tcp://hostname:61616). Provided that the User class is available in ActiveMQ classpath (pack the classes in a JAR file and include them in the lib folder of ActiveMQ), you will be able to see the Object in the Message Details of ActiveMQ console: