DZone
Thanks for visiting DZone today,
Edit Profile
  • Manage Email Subscriptions
  • How to Post to DZone
  • Article Submission Guidelines
Sign Out View Profile
  • Post an Article
  • Manage My Drafts
Over 2 million developers have joined DZone.
Log In / Join
Refcards Trend Reports Events Over 2 million developers have joined DZone. Join Today! Thanks for visiting DZone today,
Edit Profile Manage Email Subscriptions Moderation Admin Console How to Post to DZone Article Submission Guidelines
View Profile
Sign Out
Refcards
Trend Reports
Events
Zones
Culture and Methodologies Agile Career Development Methodologies Team Management
Data Engineering AI/ML Big Data Data Databases IoT
Software Design and Architecture Cloud Architecture Containers Integration Microservices Performance Security
Coding Frameworks Java JavaScript Languages Tools
Testing, Deployment, and Maintenance Deployment DevOps and CI/CD Maintenance Monitoring and Observability Testing, Tools, and Frameworks
Partner Zones AWS Cloud
by AWS Developer Relations
Culture and Methodologies
Agile Career Development Methodologies Team Management
Data Engineering
AI/ML Big Data Data Databases IoT
Software Design and Architecture
Cloud Architecture Containers Integration Microservices Performance Security
Coding
Frameworks Java JavaScript Languages Tools
Testing, Deployment, and Maintenance
Deployment DevOps and CI/CD Maintenance Monitoring and Observability Testing, Tools, and Frameworks
Partner Zones
AWS Cloud
by AWS Developer Relations
Securing Your Software Supply Chain with JFrog and Azure
Register Today

Trending

  • Operator Overloading in Java
  • RBAC With API Gateway and Open Policy Agent (OPA)
  • Competing Consumers With Spring Boot and Hazelcast
  • Extending Java APIs: Add Missing Features Without the Hassle

Trending

  • Operator Overloading in Java
  • RBAC With API Gateway and Open Policy Agent (OPA)
  • Competing Consumers With Spring Boot and Hazelcast
  • Extending Java APIs: Add Missing Features Without the Hassle
  1. DZone
  2. Coding
  3. Languages
  4. Binding to JSON & XML - Handling Collections

Binding to JSON & XML - Handling Collections

Blaise Doughan user avatar by
Blaise Doughan
·
Mar. 18, 13 · Interview
Like (0)
Save
Tweet
Share
5.96K Views

Join the DZone community and get the full member experience.

Join For Free
One of EclipseLink JAXB (MOXy)'s strengths is the ability to map an object model to both JSON and XML with a single set of metadata.  The one weakness had been that you needed to compromise on the JSON key or XML element for collection properties.  I'm happy to say that this issue has been solved in EclipseLink 2.5 (and EclipseLink 2.4.2), and I will demonstrate below with an example.

You can try this out today by downloading an EclipseLink 2.5.0 (or EclipseLink 2.4.2) nightly build starting on March 15, 2013 from:
  • http://www.eclipse.org/eclipselink/downloads/nightly.php

Domain Model 

By default a JAXB (JSR-222) implementation will not output a grouping element around collection data.  This can be done through the use of the @XmlElementWrapper annotation (see:  JAXB & Collection Properties).  This grouping element often has a plural name and is a better fit for the key of a JSON array than the repeating element defined by the @XmlElement annotation is.
package blog.json.collections;
 
import java.util.*;
import javax.xml.bind.annotation.*;
 
@XmlRootElement
@XmlType(propOrder={"name", "emailAddresses"})
public class Customer {
 
    private String name;
    private List<String> emailAddresses = new ArrayList<String>();
 
    public String getName() {
        return name;
    }
 
    public void setName(String name) {
        this.name = name;
    }
 
    @XmlElementWrapper(name="email-addresses")
    @XmlElement(name="email-address")
    public List<String> getEmailAddresses() {
        return emailAddresses;
    }
 
    public void setEmailAddresses(List<'String> emailAddresses) {
        this.emailAddresses = emailAddresses;
    }
 
}
Demo

We will specify the JSON_WRAPPER_AS_ARRAY_NAME property with a true value to tell MOXy that it should use the grouping element as the name for the JSON array value.  Then we will use the same Marshaller to output the same object to both XML and JSON.
package blog.json.collections;
 
import java.util.*;
import javax.xml.bind.*;
import org.eclipse.persistence.jaxb.MarshallerProperties;
 
public class Demo {
 
    public static void main(String[] args) throws Exception {
        Customer customer = new Customer();
        customer.setName("Jane Doe");
        customer.getEmailAddresses().add("jane.doe@example.com");
        customer.getEmailAddresses().add("jdoe@example.org");
 
        Map<String, Object> properties = new HashMap<String, Object>(1);
        properties.put(MarshallerProperties.JSON_WRAPPER_AS_ARRAY_NAME, true);
        JAXBContext jc = JAXBContext.newInstance(new Class[] {Customer.class}, properties);
 
        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
 
        // Output XML
        marshaller.marshal(customer, System.out);
 
        // Output JSON
        marshaller.setProperty(MarshallerProperties.MEDIA_TYPE, "application/json");
        marshaller.marshal(customer, System.out);
    }
 
}
XML Output

Below is the XML output from running the demo code.  We see that email-addresses is marshalled as the grouping element which contains an email-address element for each item in the collection.
<?xml version="1.0" encoding="UTF-8"?>
<customer>
   <name>Jane Doe</name>
   <email-addresses>
      <email-address>jane.doe@example.com</email-address>
      <email-address>jdoe@example.org</email-address>
   </email-addresses>
</customer>
JSON Output

The following JSON output is produced from the same metadata.  The only difference is that we told MOXy to use the grouping element as the name for JSON array values.
{
   "customer" : {
      "name" : "Jane Doe",
      "email-addresses" : [ "jane.doe@example.com", "jdoe@example.org" ]
   }
}
JAX-RS 

You can easily use MOXy as your JSON-binding provider in a JAX-RS environment (see:  MOXy as your JAX-RS JSON Provider - MOXyJsonProvider).  You can specify that the grouping element should be used as the JSON array name with the wrapperAsArrayName property on MOXyJsonProvider.
package blog.json.collections;
 
import java.util.*;
import javax.ws.rs.core.Application;
import org.eclipse.persistence.jaxb.rs.MOXyJsonProvider;
  
public class CustomerApplication  extends Application {
  
    @Override
    public Set<Class<?>> getClasses() {
        HashSet<Class<?>> set = new HashSet<Class<?>>(1);
        set.add(CustomerService.class);
        return set;
    }
  
    @Override
    public Set<Object> getSingletons() {
        MOXyJsonProvider moxyJsonProvider = new MOXyJsonProvider();
        moxyJsonProvider.setWrapperAsArrayName(true);
   
        HashSet<Object> set = new HashSet<Object>(1);
        set.add(moxyJsonProvider);
        return set;
    }
  
} 
Further Reading
If you enjoyed this post then you may also be interested in:
  • Binding to JSON & XML - Geocode Example
  • Binding to JSON & XML - Handling Null
  • Specifying EclipseLink MOXy as Your JAXB Provider




JSON XML Binding (linguistics)

Published at DZone with permission of Blaise Doughan, DZone MVB. See the original article here.

Opinions expressed by DZone contributors are their own.

Trending

  • Operator Overloading in Java
  • RBAC With API Gateway and Open Policy Agent (OPA)
  • Competing Consumers With Spring Boot and Hazelcast
  • Extending Java APIs: Add Missing Features Without the Hassle

Comments

Partner Resources

X

ABOUT US

  • About DZone
  • Send feedback
  • Careers
  • Sitemap

ADVERTISE

  • Advertise with DZone

CONTRIBUTE ON DZONE

  • Article Submission Guidelines
  • Become a Contributor
  • Visit the Writers' Zone

LEGAL

  • Terms of Service
  • Privacy Policy

CONTACT US

  • 600 Park Offices Drive
  • Suite 300
  • Durham, NC 27709
  • support@dzone.com

Let's be friends: