Its quite easy to convert a java object to XML by using Marshaller. But I need to convert a java object to JSON by using marshaller alone. I know its good to use gson or Xstream like things., but I need to do using Marshaller.How to achieve it?
Thanks in advance.
Note: I'm the EclipseLink JAXB (MOXy) lead and a member of the JAXB (JSR-222) expert group,
Below is how this can be done if you are using MOXy as your JAXB provider.
JAVA MODEL
Customer
import java.util.*; import javax.xml.bind.annotation.*; @XmlRootElement(namespace="http://www.example.com") @XmlType(namespace="http://www.example.com") @XmlAccessorType(XmlAccessType.FIELD) public class Customer { @XmlAttribute private int id; @XmlElement(namespace="http://www.example.com") private String firstName; @XmlElement(namespace="http://www.example.com", nillable=true) private String lastName; @XmlElement(namespace="http://www.example.com") private List phoneNumbers = new ArrayList(); } PhoneNumber
import javax.xml.bind.annotation.*; @XmlAccessorType(XmlAccessType.FIELD) public class PhoneNumber { @XmlAttribute private String type; @XmlValue private String number; } jaxb.properties
To specify MOXy as your JAXB provider you need to include a file called jaxb.properties in the same package as your domain model with the following entry (see: http://blog.bdoughan.com/2011/05/specifying-eclipselink-moxy-as-your.html)
javax.xml.bind.context.factory=org.eclipse.persistence.jaxb.JAXBContextFactory DEMO CODE
input.xml
Jane 555-1111 Demo
In the demo code below we will use the same JAXB metadata to convert an XML document to Java objects, and then convert those objects back to JSON. With MOXy you can specify JSON output by setting a property on the Marshaller.
import java.io.File; import javax.xml.bind.*; import org.eclipse.persistence.jaxb.MarshallerProperties; public class Demo { public static void main(String[] args) throws Exception { JAXBContext jc = JAXBContext.newInstance(Customer.class); Unmarshaller unmarshaller = jc.createUnmarshaller(); File xml = new File("src/forum15357366/input.xml"); Customer customer = (Customer) unmarshaller.unmarshal(xml) ; Marshaller marshaller = jc.createMarshaller(); marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true); marshaller.setProperty(MarshallerProperties.MEDIA_TYPE, "application/json"); marshaller.setProperty(MarshallerProperties.JSON_INCLUDE_ROOT, false); marshaller.marshal(customer, System.out); } } JSON Output
Below is the JSON output. Note how there are no indicators corresponding to namespaces or XML attributes. Also note the collection of size one was correctly represented as a JSON array (a problem with some other approaches).
{ "id" : 123, "firstName" : "Jane", "lastName" : null, "phoneNumbers" : [ { "type" : "work", "value" : "555-1111" } ] } JsonMarshaller is a Java 1.5 library that allows marshalling and unmarshalling of JSON objects to and from Java objects. This project's goal is above all ease of use, transparency and static type safety. Example
If you have the following Java class:
JAVA:
@Entity class Book { @Value private String title; @Value private String isbn; @Value private Set authors; } @Entity class Author { @Value private String firstName; @Value private String lastName; } and you created a new Book() and populated it with info it could marshal too:
JSON: {title: "java", isbn: "122333", authors: [{firstName: "Herbert", lastName: "Shield"}, {firstName: "Pascal", lastName: "Perez"}]}