Apache camel: Xml file to JSON file.

Hi there,

I started learning Apache Camel a few days ago and was having difficulty with this simple case: Creating a JSON file from an XML file.

Problem 1: Old version

I picked up a project from a course I was taking. And the version used in this course was out of date. The course was using the dependency 'camel-xmljson,' which has since been removed in the new version.

Upgrading project

So I've decided to upgrade project to use Java 17 and apache camel version 3.18.0.

To do this, I've needed to import new dependencies on project:

<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-jaxb</artifactId>
    <version>${camel-version}</version>
</dependency>
<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-jackson</artifactId>
    <version>${camel-version}</version>
</dependency>
<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-jacksonxml</artifactId>
    <version>${camel-version}</version>
</dependency>

Refactoring the code

After import the new dependencies, I needed to refactor my code.

Before refactoring

The code was as follows:

public static void main(String[] args) throws Exception {

        CamelContext context = new DefaultCamelContext();
        context.addRoutes(new RouteBuilder() {

            @Override
            public void configure() throws Exception {

                from("file:pedidos?delay=5s&noop=true").
                    split().
                        xpath("/pedido/itens/item").
                    filter().
                        xpath("/item/formato[text()='EBOOK']").
                    marshal().xmljson().
                    log("${id} - ${body}").
                    setHeader(Exchange.FILE_NAME, simple("${file:name.noext}-${header.CamelSplitIndex}.json")).
                to("file:saida");
            }

        });

        context.start();
        Thread.sleep(20000);
        context.stop();
    }

After refactoring

And now I needed to do this:

public static void main(String[] args) throws Exception {

        try (CamelContext context = new DefaultCamelContext()) {
            JacksonDataFormat jacksonDataFormat = new JacksonDataFormat();
            jacksonDataFormat.setPrettyPrint(true);
            jacksonDataFormat.enableFeature(SerializationFeature.WRAP_ROOT_VALUE);

            context.addRoutes(new RouteBuilder() {

                @Override
                public void configure() throws Exception {

                    from("file:input?delay=5s&noop=true")
                        .filter()
                            .xpath("/pedido/itens/item/formato[text()='EBOOK']")
                        .unmarshal().jacksonXml(Pedido.class)
                        .marshal(jacksonDataFormat)
                        .setHeader(Exchange.FILE_NAME, simple("${file:name.noext}.json"))
                        .to("file:output");
                }

            });

            context.start();
            Thread.sleep(20000);
            context.stop();
        }
    }

I needed to use some jackson annotations in "Pedido.java":

import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlProperty;
import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlRootElement;

@JacksonXmlRootElement(localName = "pedido")
public class Pedido {

    @JacksonXmlProperty(localName = "id")
    private String id;
    @JacksonXmlProperty(localName = "dataCompra")
    private String dataCompra;
    @JacksonXmlProperty(localName = "itens")
    private Itens itens;
    @JacksonXmlProperty(localName = "pagamento")
    private Pagamento pagamento;

....
// getters and setters

Note that 'Before refactoring,' I only needed to use'marshal().xmljson(),' and 'After refactoring,' I needed to do the following:

JacksonDataFormat jacksonDataFormat = new JacksonDataFormat();
jacksonDataFormat.setPrettyPrint(true);
jacksonDataFormat.enableFeature(SerializationFeature.WRAP_ROOT_VALUE);

.unmarshal().jacksonXml(Pedido.class)
.marshal(jacksonDataFormat)

Conclusion

Well, this was the solution I discovered.

I know, there must be a better method, and if you know, left your comment and help me improve. :D

Thank you very much and see you!

André Moriya @andremoriya