xml to json converter

[Mukul Gandhi <mukulg@softwarebytes.org>]

Hi all,

    I've been playing around today, with this topic and thought of sharing my findings with people here.

I wrote an XML to JSON converter, using following tools,

1. Little bit of java programming

2. JAXB

3. jackson-databind library

This XML to JSON converter, works for particular XSD documents, and then can convert XML instance documents conforming to a specific XSD document to a JSON document.

Below are the steps I followed, along with an example.

1) Write an XSD document

Here's what I wrote for this example (named x1.xsd),

<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">

    <xs:element name="X">
       <xs:complexType>
          <xs:sequence>
             <xs:element name="a" maxOccurs="unbounded">
                <xs:complexType>
                   <xs:sequence>
                      <xs:element name="b" type="xs:string" maxOccurs="unbounded"/>
                   </xs:sequence>
                   <xs:attribute name="id" type="xs:integer"/>
                </xs:complexType>
             </xs:element>
          </xs:sequence>
       </xs:complexType>
    </xs:element>

</xs:schema>

2) Use JAXB command xjc as follows,

xjc -d java_mapping -p com.example x1.xsd

This generates following java files,

ObjectFactory.java

X.java

3) Write a java program as follows,

import java.io.File;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Unmarshaller;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;

public class XmlToJsonConverter {

       public static void main(String[] args) {
            File xmlFile = new File(args[0]);   // pass in an XML instance document file path

           try {
                 JAXBContext jaxbContext = JAXBContext.newInstance(X.class);  
                 Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();  
                 X x = (X)jaxbUnmarshaller.unmarshal(xmlFile);
                 ObjectMapper objectMapper = new ObjectMapper();
                 String jsonStr = objectMapper.writerWithDefaultPrettyPrinter().writeValueAsString(x);
                 System.out.println(jsonStr);
            }
            catch (JAXBException ex) {
                ex.printStackTrace();
            } 

            catch (JsonProcessingException ex) {
                ex.printStackTrace();
            }
       }
}

4) Run the above java program, providing it the following XML instance document,

<?xml version="1.0"?>
<X>
  <a id="1">
    <b>hello</b>
    <b>world</b>    
  </a>
  <a id="2">
    <b>I'm</b>
    <b>fine</b>    
  </a>
</X>

The following JSON output is produced,

{
  "a" : [ {
    "b" : [ "hello", "world" ],
    "id" : 1
  }, {
    "b" : [ "I'm", "fine" ],
    "id" : 2
  } ]
}

That's all about this.

Any comments are welcome.

--

Regards,

Mukul Gandhi