How to use spring to marshal and unmarshal xml? - spring

Question

I have a spring boot project. I have a few xsds in my project. I have generated the classes using maven-jaxb2-plugin. I have used this tutorial to get a sample spring boot application running.
import org.kaushik.xsds.XOBJECT;
#SpringBootApplication
public class JaxbExample2Application {
public static void main(String[] args) {
//SpringApplication.run(JaxbExample2Application.class, args);
XOBJECT xObject = new XOBJECT('a',1,2);
try {
JAXBContext jc = JAXBContext.newInstance(User.class);
Marshaller marshaller = jc.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
marshaller.marshal(xObject, System.out);
} catch (PropertyException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (JAXBException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
But my concern is that I need to have all the jaxb classes of the schema mapped. Also is there something in Spring that I can use to make my task easier. I have looked at the Spring OXM project but it had application context configured in xml. Does spring boot have anything that I can use out of the box. Any examples will be helpful.
Edit
I tried xerx593's answer and I ran a simple test using main method
JaxbHelper jaxbHelper = new JaxbHelper();
Jaxb2Marshaller marshaller = new Jaxb2Marshaller();
marshaller.setClassesToBeBound(XOBJECT.class);
jaxbHelper.setMarshaller(marshaller);
XOBJECT xOBJECT= (PurchaseOrder)jaxbHelper.load(new StreamSource(new FileInputStream("src/main/resources/PurchaseOrder.xml")));
System.out.println(xOBJECT.getShipTo().getName());
It ran perfectly fine. Now I just need to plug it in using spring boot.

Answer 1

OXM is definitely the right for you!
A simple java configuration of a Jaxb2Marshaller would look like:
//...
import java.util.HashMap;
import org.springframework.oxm.jaxb.Jaxb2Marshaller;
//...
#Configuration
public class MyConfigClass {
#Bean
public Jaxb2Marshaller jaxb2Marshaller() {
Jaxb2Marshaller marshaller = new Jaxb2Marshaller();
marshaller.setClassesToBeBound(new Class[]{
//all the classes the context needs to know about
org.kaushik.xsds.All.class,
org.kaushik.xsds.Of.class,
org.kaushik.xsds.Your.class,
org.kaushik.xsds.Classes.class
});
// "alternative/additiona - ly":
// marshaller.setContextPath(<jaxb.context-file>)
// marshaller.setPackagesToScan({"com.foo", "com.baz", "com.bar"});
marshaller.setMarshallerProperties(new HashMap<String, Object>() {{
put(javax.xml.bind.Marshaller.JAXB_FORMATTED_OUTPUT, true);
// set more properties here...
}});
return marshaller;
}
}
In your Application/Service class you could approach like this:
import java.io.InputStream;
import java.io.StringWriter;
import javax.xml.bind.JAXBException;
import javax.xml.transform.Result;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.stream.StreamSource;
import org.springframework.oxm.jaxb.Jaxb2Marshaller;
#Component
public class MyMarshallerWrapper {
// you would rather:
#Autowired
private Jaxb2Marshaller marshaller;
// than:
// JAXBContext jc = JAXBContext.newInstance(User.class);
// Marshaller marshaller = jc.createMarshaller();
// marshalls one object (of your bound classes) into a String.
public <T> String marshallXml(final T obj) throws JAXBException {
StringWriter sw = new StringWriter();
Result result = new StreamResult(sw);
marshaller.marshal(obj, result);
return sw.toString();
}
// (tries to) unmarshall(s) an InputStream to the desired object.
#SuppressWarnings("unchecked")
public <T> T unmarshallXml(final InputStream xml) throws JAXBException {
return (T) marshaller.unmarshal(new StreamSource(xml));
}
}
See Jaxb2Marshaller-javadoc, and a related Answer

Answer 2

If you just want serializing/deserializing bean with XML. I think jackson fasterxml is one good choice:
ObjectMapper xmlMapper = new XmlMapper();
String xml = xmlMapper.writeValueAsString(new Simple()); // serializing
Simple value = xmlMapper.readValue("<Simple><x>1</x><y>2</y></Simple>",
Simple.class); // deserializing
maven:
<dependency>
<groupId>com.fasterxml.jackson.dataformat</groupId>
<artifactId>jackson-dataformat-xml</artifactId>
</dependency>
Refer: https://github.com/FasterXML/jackson-dataformat-xml

Answer 3

Spring BOOT is very smart and it can understand what you need with a little help.
To make XML marshalling/unmarshalling work you simply need to add annotations #XmlRootElement to class and #XmlElement to fields without getter and target class will be serialized/deserialized automatically.
Here is the DTO example
package com.exmaple;
import lombok.AllArgsConstructor;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;
import lombok.ToString;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
import java.io.Serializable;
import java.util.Date;
import java.util.Random;
#AllArgsConstructor
#NoArgsConstructor
#ToString
#Setter
#XmlRootElement
public class Contact implements Serializable {
#XmlElement
private Long id;
#XmlElement
private int version;
#Getter private String firstName;
#XmlElement
private String lastName;
#XmlElement
private Date birthDate;
public static Contact randomContact() {
Random random = new Random();
return new Contact(random.nextLong(), random.nextInt(), "name-" + random.nextLong(), "surname-" + random.nextLong(), new Date());
}
}
And the Controller:
package com.exmaple;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
#Controller
#RequestMapping(value="/contact")
public class ContactController {
final Logger logger = LoggerFactory.getLogger(ContactController.class);
#RequestMapping("/random")
#ResponseBody
public Contact randomContact() {
return Contact.randomContact();
}
#RequestMapping(value = "/edit", method = RequestMethod.POST)
#ResponseBody
public Contact editContact(#RequestBody Contact contact) {
logger.info("Received contact: {}", contact);
contact.setFirstName(contact.getFirstName() + "-EDITED");
return contact;
}
}
You can check-out full code example here: https://github.com/sergpank/spring-boot-xml
Any questions are welcome.

Answer 4

You can use StringSource / StringResult to read / read xml source with spring
#Autowired
Jaxb2Marshaller jaxb2Marshaller;
#Override
public Service parseXmlRequest(#NonNull String xmlRequest) {
return (Service) jaxb2Marshaller.unmarshal(new StringSource(xmlRequest));
}
#Override
public String prepareXmlResponse(#NonNull Service xmlResponse) {
StringResult stringResult = new StringResult();
jaxb2Marshaller.marshal(xmlResponse, stringResult);
return stringResult.toString();
}