Data Transformation: XML to JSON And JSON to XML With Apache Camel

1.0 Overview

Apache Camel provides a rich set of libraries to perform XML to JSON and JSON to XML transformation.

• marshalling => converting from XML to JSON
• un-marshaling => converting from JSON to XML.

2.0 Explicitly Instantiating the DataFormat

We need to instantiate the XmlJsonDataFormat from package org.apache.camel.dataformat.xmljson.XmlJsonDataFormat and make sure that camel-xmljson is added in your pom.xml or an installed camel-xmljson feature.

XmlJsonDataFormat xmlJsonFormat = new XmlJsonDataFormat();

2.1 XmlJsonDataFormat Property

XmlJsonDataFormat xmlJsonFormat = new XmlJsonDataFormat();
xmlJsonFormat.setEncoding("UTF-8");
xmlJsonFormat.setForceTopLevelObject(true);
xmlJsonFormat.setTrimSpaces(true);
xmlJsonFormat.setRootName("Employee");
xmlJsonFormat.setSkipNamespaces(true);
xmlJsonFormat.setRemoveNamespacePrefixes(true);
xmlJsonFormat.setExpandableProperties(Arrays.asList("d", "e"));

These properties are not mandatory and can be used when you want to tune the message.

2.2 Marshalling/Unmarshalling

Once XMLJsonDataFormat is instantiated, the next step is to use it as a parameter to  marshal() / unmarshal()  DSL elements.

Marshalling (converting from XML to JSON):

from("direct:unMarshalEmployeejson2xml")
                .unmarshal(xmlJsonFormat)
                .to("log:?level=INFO&showBody=true");

Un-Marshalling (converting from JSON to XML):

  from("direct:marshalEmployeexml2json")
                .marshal(xmlJsonFormat)
                .to("log:?level=INFO&showBody=true");

3.0 Defining Data Format In-Line

It is also possible to define the data format inline using the xmljson() DSL element:

  from("direct:unMarshalEmployeejson2xml")
                .unmarshal().xmljson()
                .to("log:?level=INFO&showBody=true");

from("direct:marshalEmployeexml2json")
                .marshal().xmljson()
                .to("log:?level=INFO&showBody=true");

It is also possible to pass Map to the inline method, as shown below.

Map<String, String> xmlJsonOptions = new HashMap<String, String>();

xmlJsonOptions.put(org.apache.camel.model.dataformat.XmlJsonDataFormat.ENCODING, "UTF-8");
xmlJsonOptions.put(org.apache.camel.model.dataformat.XmlJsonDataFormat.ROOT_NAME, "Employee");
xmlJsonOptions.put(org.apache.camel.model.dataformat.XmlJsonDataFormat.SKIP_NAMESPACES, "true");
xmlJsonOptions.put(org.apache.camel.model.dataformat.XmlJsonDataFormat.REMOVE_NAMESPACE_PREFIXES, "true");
xmlJsonOptions.put(org.apache.camel.model.dataformat.XmlJsonDataFormat.EXPANDABLE_PROPERTIES, "d e");

 from("direct:unMarshalEmployeejson2xml")
                .unmarshal().xmljson(xmlJsonOptions)
                .to("log:?level=INFO&showBody=true");

from("direct:marshalEmployeexml2json")
                .marshal().xmljson(xmlJsonOptions)
                .to("log:?level=INFO&showBody=true");

4.0 POM Dependency

We need to add some dependencies into the pom file to perform XML2JSON and JSON2XML transformation.

<?xml version="1.0" encoding="UTF-8"?>
<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>com.learncamel</groupId>
    <artifactId>learncamel-transform</artifactId>
    <version>1.0-SNAPSHOT</version>
    <dependencies>
        <dependency>
            <groupId>org.apache.camel</groupId>
            <artifactId>camel-core</artifactId>
            <version>2.19.1</version>
        </dependency>
        <dependency>
            <groupId>org.apache.camel</groupId>
            <artifactId>camel-test</artifactId>
            <version>2.19.1</version>
        </dependency>
        <dependency>
            <groupId>org.apache.camel</groupId>
            <artifactId>camel-xmljson</artifactId>
            <version>2.19.0</version>
        </dependency>
        <dependency>
            <groupId>xom</groupId>
            <artifactId>xom</artifactId>
            <version>1.2.5</version>
        </dependency>

        <dependency>
            <groupId>commons-logging</groupId>
            <artifactId>commons-logging</artifactId>
            <version>1.1.3</version>
        </dependency>

        <dependency>
            <groupId>net.sf.ezmorph</groupId>
            <artifactId>ezmorph</artifactId>
            <version>1.0.6</version>
        </dependency>

        <dependency>
            <groupId>commons-collections</groupId>
            <artifactId>commons-collections</artifactId>
            <version>3.2.1</version>
        </dependency>

        <dependency>
            <groupId>commons-beanutils</groupId>
            <artifactId>commons-beanutils</artifactId>
            <version>1.8.3</version>
        </dependency>

        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>1.7.12</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>1.7.12</version>
        </dependency>
    </dependencies>
</project>

5.0 Code

5.1 Defining Route

package com.learncamel.route.xml2json;

import org.apache.camel.Route;
import org.apache.camel.builder.RouteBuilder;
import org.apache.camel.dataformat.xmljson.XmlJsonDataFormat;

public class XML2JSONRoute extends RouteBuilder {

    public void configure() throws Exception {

        from("direct:marshalEmployeexml2json")
                .to("log:?level=INFO&showBody=true")
                .marshal().xmljson()
                .to("log:?level=INFO&showBody=true");


        final XmlJsonDataFormat xmlJsonFormat = new XmlJsonDataFormat();
        xmlJsonFormat.setRootName("Employee");

        from("direct:unMarshalEmployeejson2xml")
                //.unmarshal().xmljson()
                .unmarshal(xmlJsonFormat)
                .to("log:?level=INFO&showBody=true");

    }
}

5.2 Unit Test 

To test the above routes, you can define unit test cases and you will require the camel-test feature installed, or it can be added into the pom.xml dependency.

package com.learncamel.route.xml2json;

import org.apache.camel.builder.RouteBuilder;
import org.apache.camel.test.junit4.CamelTestSupport;
import org.junit.Test;


public class XML2JSONRouteTest extends CamelTestSupport {

    @Override
    protected RouteBuilder createRouteBuilder() throws Exception {
        return new XML2JSONRoute();
    }

    @Test
    public void marshalEmployeeJSON2XML(){

        String expected = "{\"id\":\"123 \",\"name\":\"ABC\",\"type\":\"senior\"}";
        String request = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\r\n" +
                "<Employee><id>123 </id><name>ABC</name><type>senior</type></Employee>\r\n";

        final String response = template.requestBody("direct:marshalEmployeexml2json", request, String.class);
        System.out.println("response is : " + response);

        assertEquals(expected, response);

    }

    @Test
    public void unMarshalEmployeeJSON2XML(){

        final String request = "{\"name\":\"ABC\",\"id\":\"123 \",\"type\":\"senior\"}";

        final String response = template.requestBody("direct:unMarshalEmployeejson2xml", request, String.class);
        System.out.println("response is : " + response);
        String expected = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\r\n" +
                "<Employee><id>123 </id><name>ABC</name><type>senior</type></Employee>\r\n";
        assertEquals(expected, response);

    }
}

Now, you know how to convert XML to JSON and JSON to XML with Apache Camel.