Develop Reference

Unmarshal XML attribute to object value

I'm working on a school project where I have to bind some XML values from an API to a java object. I am able to get all the elements, I can't however get the attribute of a specific element. I've looked around for a solution, but couldn't find one.
I have this piece of XML code that I want to unmarshal with JAXB to a Java object. The attribute I would like to get is 'changes' in Departuretrack.
<Departures>
<DepartingTrain>
<Id>220</Id>
<DepartureTime>2017-03-07T11:03:00+0100</DepartureTime>
<DepartureTrack changes="false">5</DepartureTrack>
</DepartingTrain>
<DepartingTrain>
<Id>637</Id>
<DepartureTime>2017-03-07T11:18:00+0100</DepartureTime>
<DepartureTrack changes="false">12</DepartureTrack>
</DepartingTrain>
</Departures>
I do currently have this object, it does work for all the elements. I don't know how to get the attribute 'changes' and put it into this object.
#Entity
#Getter
#Setter
#NoArgsConstructor
#XmlRootElement(name="Departures")
#XmlAccessorType(XmlAccessType.FIELD)
public class Departure {
#Id
#GeneratedValue
private long id;
#XmlElement(name="Id")
private int routeNumber;
#XmlElement(name="DepartureTime")
private String departureTime;
#XmlElement(name="DepartureTrack")
private String departureTrack;
}
I create a list with all the departures with this object.
#Entity
#Getter
#Setter
#NoArgsConstructor
#XmlRootElement(name="Departures")
#XmlAccessorType(XmlAccessType.FIELD)
public class DepartureList {
#Id
#GeneratedValue
private long id;
#XmlElement(name="DepartingTrain")
#OneToMany
private List<Departure> departures = new ArrayList<>();
}
This is what my unmarshaller looks like.
// Returns all departures for a specific station
public DepartureList getDepartingTrains(String station){
try {
URL url = new URL("API URL" + station);
URLConnection urlConnection = url.openConnection();
urlConnection.setRequestProperty("Authorization", "Basic " + authStringEnc);
InputStream is = urlConnection.getInputStream();
InputStreamReader isr = new InputStreamReader(is);
Unmarshaller unmarshaller = departureListJaxbContext.createUnmarshaller();
DepartureList departureList = (DepartureList) unmarshaller.unmarshal(isr);
return departureList;
} catch (JAXBException e) {
e.printStackTrace();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
// Throw Exception
return null;
}
Does anyone know how to get this attribute from the XML sheet and put it into the Java object?

Add the "changes" attribute under DepartureTrack JAXB Generated class as below:
import javax.xml.bind.annotation.*;
#XmlAccessorType(XmlAccessType.FIELD)
#XmlRootElement
public class DepartureTrack {
#XmlAttribute
protected String changes;
#XmlValue;
protected String content;
}

You should have java classes like below
import org.simpleframework.xml.Attribute;
import org.simpleframework.xml.Element;
import org.simpleframework.xml.ElementList;
import org.simpleframework.xml.Root;
import java.math.BigDecimal;
import java.util.List;
#Root(name = "Departures")
public class Departures {
#ElementList(name = "DepartingTrain", inline = true, required = false)
List<DepartingTrain> departingTrain;
public List<DepartingTrain> getDepartingTrain() { return this.departingTrain; }
public void setDepartingTrain(List<DepartingTrain> _value) { this.departingTrain = _value; }
public static class DepartingTrain {
#Element(name="Id", required = false)
String id;
#Element(name="DepartureTime", required = false)
String departureTime;
#Element(name="DepartureTrack", required = false)
DepartureTrack departureTrack;
public String getId() { return this.id; }
public void setId(String _value) { this.id = _value; }
public String getDepartureTime() { return this.departureTime; }
public void setDepartureTime(String _value) { this.departureTime = _value; }
public DepartureTrack getDepartureTrack() { return this.departureTrack; }
public void setDepartureTrack(DepartureTrack _value) { this.departureTrack = _value; }
}
public static class DepartureTrack {
#Attribute(name="changes", required = false)
Boolean changes;
public Boolean getChanges() { return this.changes; }
public void setChanges(Boolean _value) { this.changes = _value; }
}
}
and there are few sites which provide to create java classes from the xml or json.
http://pojo.sodhanalibrary.com/Convert
http://rnevet.github.io/simple-xml-pojo-gen/
http://pojo.sodhanalibrary.com/pojoFromXSD.html

How to name complex objects in JAXB/JSON?

#XmlRootElement(name = "test")
public class MyDTO {
#XmlElement(name = "test2)
private MyObject meta;
}
Result:
{meta:{...}}
Problems:
I'd like to have some kind of "outer" tag named "test"
Why is the #XmlElement(name" attribute for meta not working?

my first post!
Indeed you can name your "outer" tag with #XmlRootElement. If you need another outer tag I am not sure how to realize this.
Your second concern might be because of the place where you put the #XmlElement. I placed it on my getter-method and it worked fine fore me.
For the JSON Output I used jersey-json-1.18.
The following works also for other complex types you could define instead of "String meta".
Here is the output I was able to produce:
As JSON
{"myId":"id1","myMeta":"text1"}
As XML
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<mytupel>
<myId>id1</myId>
<myMeta>text1</myMeta>
</mytupel>
This is my object:
#XmlRootElement(name = "mytupel")
public class Tupel {
// #XmlElement(name = ) does not work here - defined it on the getter method
private String id;
// #XmlElement(name = ) does not work here - defined it on the getter method
private String meta;
/**
* Needed for JAXB
*/
public Tupel() {
}
/**
* For Test purpose...
*/
public Tupel(String id, String text) {
super();
this.id = id;
this.meta = text;
}
#XmlElement(name = "myId")
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
#XmlElement(name = "myMeta")
public String getMeta() {
return meta;
}
public void setMeta(String meta) {
this.meta = meta;
}
/**
* For Test purpose...
*/
#Override
public String toString() {
return id + ": " + meta;
}
}
And here is my small class to produce the output XML files...
public class Main {
private static final String TUPEL_1_XML = "./tupel1.xml";
private static final String TUPEL_2_XML = "./tupel2.xml";
public static void main(String[] args) throws JAXBException, FileNotFoundException {
// init JAXB context/Marhsaller stuff
JAXBContext context = JAXBContext.newInstance(Tupel.class);
Marshaller marshaller = context.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
Unmarshaller unmarshaller = context.createUnmarshaller();
// create some Datatypes
Tupel data1 = new Tupel("id1", "text1");
Tupel data2 = new Tupel("id2", "42");
// produce output
marshaller.marshal(data1, new File(TUPEL_1_XML));
marshaller.marshal(data2, new File(TUPEL_2_XML));
// read from produced output
Tupel data1FromXml = (Tupel) unmarshaller.unmarshal(new FileReader(TUPEL_1_XML));
Tupel data2FromXml = (Tupel) unmarshaller.unmarshal(new FileReader(TUPEL_2_XML));
System.out.println(data1FromXml.toString());
System.out.println(data2FromXml.toString());
System.out.println(marshalToJson(data1FromXml));
System.out.println(marshalToJson(data2FromXml));
}
public static String marshalToJson(Object o) throws JAXBException {
StringWriter writer = new StringWriter();
JAXBContext context = JSONJAXBContext.newInstance(o.getClass());
Marshaller m = context.createMarshaller();
JSONMarshaller marshaller = JSONJAXBContext.getJSONMarshaller(m, context);
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
marshaller.marshallToJSON(o, writer);
return writer.toString();
}
}
Hope this answers your question!
Cheers
Max

JAXB unmarshal mystery XML

I am using JAXB to unmarshal an XML file.
All I know about the XML file is that it is valid XML.
How then am I supposed to specify a class and/or package to newInstance?
JAXBContext jaxbContext = JAXBContext.newInstance(??????);
Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();
Object o = (Object) unmarshaller.unmarshal(myFile);
I did not see anything in the docs that address this issue.

You need to tell JaxB what class to unmarshall to so that it can use the annotations in the class to resolve the hierarchy of the xml. You will need to have a class that is also annotated with something like #XmlRootElement. If you want to parse arbitrary xml you will probably need to do something with a DocumentBuilder or xpath.
See this artical for more info.
http://blog.bdoughan.com/2012/11/creating-generic-list-wrapper-in-jaxb.html
I have used something like this to convert arbitrary xml to a class. The any field will actually be a list of org.w3c.dom.Element in which you can get information from.
http://docs.oracle.com/javase/7/docs/api/org/w3c/dom/Element.html
#XmlRootElement
class Wrapper {
/**
* Everything else
*/
#Transient
#XmlAnyElement(lax = true)
private List<Element> any;
public List<Element> getAny() {
return any;
}
}

In newInstance you must add the class root element that map your xml... below an example
Here an example ..
public static void main(String[] args) throws JAXBException {
final JAXBContext context = JAXBContext.newInstance(Vehicals.class);
final Marshaller m = context.createMarshaller();
m.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
final Vehicals vehicals = new Vehicals();
List<Car> cars = new ArrayList<Car>();
Car c = new Car();
c.setName("Mercedes");
cars.add(c);
c = new Car();
c.setName("BMW");
cars.add(c);
vehicals.setCar(cars);
m.marshal(vehicals, System.out);
}
Vehicals.java
import java.util.List;
import javax.xml.bind.annotation.XmlRootElement;
#XmlRootElement
public class Vehicals {
private List<Car> Car;
public List<Car> getCar() {
return Car;
}
public void setCar(List<Car> cars) {
this.Car = cars;
}
}
Car.java
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlTransient;
#XmlRootElement
public class Car {
#XmlTransient
private Long id;
private String name;
#XmlTransient
private String code;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getCode() {
return code;
}
public void setCode(String code) {
this.code = code;
}
}
output.xml
<Vehicle>
<Car>
<name>Mercedes</name>
</Car>
<Car>
<name>BMW</name>
</Car>
</Vehicle>
For the Unmarshal is the same thing. In my case i added Vehicals as parameter in newInstance method.

Exception in thread "main" java.lang.NullPointerException when using Jaxb unmarshal/marshal

I'm using JAXB to unmarshal a given input Xml file into Java object
and then marashal it back to Xml String.
My Xml file looks like this:
<bpmn2:definitions xmlns:bpmn2="http://www.omg.org/spec/BPMN/20100524/MODEL" id="_Definitions_1">
<bpmn2:process id="_500441" name="process">
</bpmn2:process>
</bpmn2:definitions>
Definitions.class:
#XmlRootElement(namespace = "http://www.omg.org/spec/BPMN/20100524/MODEL")
public class Definitions {
#XmlAttribute
private String id;
#XmlElement(name = "bpmn2:process")
private Process process;
#XmlElement(name = "bpmndi:BPMNDiagram")
private Diagram diagram;
public Definitions() {
}
public Definitions(String id, Process process, Diagram diagram) {
this.id = id;
this.process = process;
this.diagram = diagram;
}
public Process getProcess() {
return process;
}
public Diagram getDiagram() {
return diagram;
}
public String getId() {
return id;
}
}
Process.class:
#XmlAccessorType(XmlAccessType.FIELD)
public class Process {
#XmlAttribute
private String id;
public Process() {
}
public Process(String id) {
this.id = id;
}
public String getId() {
return id;
}
}
Model.class:
public class Model {
#XmlElement
private Process process;
public Model() {
}
public Model(String processId, Process p) {
this.id = processId;
this.process = p;
}
}
main method:
public static void main(String[] args) throws IOException, JSONException, JAXBException {
BpmnToJsonImport bj = new BpmnToJsonImport();
InputStream is = BpmnToJsonImport.class.getResourceAsStream("myXml.txt");
String Str = IOUtils.toString(is);
StringReader sr = new StringReader(Str);
JAXBContext context = JAXBContext.newInstance(Definitions.class, Model.class);
Unmarshaller unmarshaller = context.createUnmarshaller();
Definitions d = (Definitions) unmarshaller.unmarshal(sr);
Model model = new Model(d.getProcess().getId(), d.getProcess());
StringWriter sw = new StringWriter();
Marshaller marshaller = context.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
marshaller.setProperty(Marshaller.JAXB_ENCODING, "UTF-8");
marshaller.marshal(model, sw);
String str = sw.toString();
System.out.println(str);
}
Exactly when it tries to retrieve the process id using d.getProcess.getId I get the
java.lang.NullPointerException

You are mapping the namespace qualification incorrectly. You must not include the prefix in the element name.
#XmlElement(name = "BPMNDiagram")
private Diagram diagram;
To map the namespace qualification you can use the package level #XmlSchema annotation.
package-info.java
#XmlSchema(
namespace = "http://www.omg.org/spec/BPMN/20100524/MODEL",
elementFormDefault = XmlNsForm.QUALIFIED)
package example;
import javax.xml.bind.annotation.XmlNsForm;
import javax.xml.bind.annotation.XmlSchema;
For More Information
http://blog.bdoughan.com/2010/08/jaxb-namespaces.html

Default namespace & complex package/data structure

I need create/read xml file using default namespace:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<xmlBoo xmlns="http://www.example2.org/boo">
<customer>
<address>
<street>Wall Street</street>
</address>
<id>1</id>
<name>John</name>
</customer>
<someSpecificField>Specific data in Boo</ns2:someSpecificField>
</xmlBoo>
but I'm getting:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<ns2:xmlBoo xmlns:ns2="http://www.example2.org/boo">
<ns2:customer>
<address>
<street>Wall Street</street>
</address>
<id>1</id>
<name>John</name>
</ns2:customer>
<ns2:someSpecificField>Specific data in Boo</ns2:someSpecificField>
</ns2:xmlBoo>
I know about package level metadata, but this is not working in complex package structure:
I have defined model classes like Address:
package example.model;
public class Address {
private String street;
Customer:
package example.model;
public class Customer {
private long id;
private String name;
private Address address;
The parent class for common fields:
package example.xml;
#XmlTransient
public class Xml {
private Customer customer;
Then specific classes which holds data/structure of concrete xml XmlBoo:
package example.xml.boo;
#XmlRootElement
public class XmlBoo extends Xml {
private String someSpecificField;
XmlFoo:
package example.xml.foo;
#XmlRootElement
public class XmlFoo extends Xml {}
package-info.java is included in two mentioned packages example.xml.boo:
#XmlSchema(
namespace = "http://www.example2.org/boo",
elementFormDefault = XmlNsForm.QUALIFIED)
package example.xml.boo;
and example.xml.foo:
#XmlSchema(
namespace = "http://www.example2.org/foo",
elementFormDefault = XmlNsForm.QUALIFIED)
package example.xml.foo;
And finally main method:
package example;
public class Demo {
public static void main(String... args) {
generateBoo();
generateFoo();
}
public static void generateBoo() {
try {
JAXBContext jc = JAXBContext.newInstance(XmlBoo.class);
Marshaller m = jc.createMarshaller();
m.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
XmlBoo xmlBoo = new XmlBoo();
Customer customer = new Customer();
customer.setId(1);
customer.setName("John");
Address address = new Address();
address.setStreet("Wall Street");
customer.setAddress(address);
xmlBoo.setCustomer(customer);
xmlBoo.setSomeSpecificField("Specific data in Boo");
m.marshal(xmlBoo, System.out);
} catch (JAXBException e) {
e.printStackTrace();
}
}
public static void generateFoo() {
try {
JAXBContext jc = JAXBContext.newInstance(XmlFoo.class);
Marshaller m = jc.createMarshaller();
m.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
XmlFoo xmlFoo = new XmlFoo();
Customer customer = new Customer();
customer.setId(1);
customer.setName("John");
Address address = new Address();
address.setStreet("Wall Street");
customer.setAddress(address);
xmlFoo.setCustomer(customer);
m.marshal(xmlFoo, System.out);
} catch (JAXBException e) {
e.printStackTrace();
}
}
}
I've tried both solutions like here and also without success.
It is possible remove & rename prefix if I have all classes in one package (and one package-info file)
It is possible rename but NOT remove prefix if I have complex package structure
Is there solution how I can remove ns2 prefix?
I'm using JDK7.

Solution how get (write & read xml) the needed result:
<?xml version="1.0" encoding="UTF-8"?>
<xmlBoo xmlns="http://www.example.org/boo" xmlns:c="http://www.example.org/customer" xmlns:a="http://www.example.org/address" xmlns:h="http://www.example.org/header">
<h:header>
<h:id>101</h:id>
</h:header>
<c:customer>
<c:id>1</c:id>
<c:name>Yen</c:name>
<a:address>
<a:street>Long street</a:street>
</a:address>
</c:customer>
<someBooSpecificField>Specific data in Boo</someBooSpecificField>
</xmlBoo>
for root element and its "simple" children is used default namespace (without prefix)
for complex (objects in java) children are used different namespaces (mapped to different prefixes)
model classes are in different packages
So here is the solution:
Define MOXy implementation of JAXB, file: jaxb.properties
javax.xml.bind.context.factory=org.eclipse.persistence.jaxb.JAXBContextFactory
Create abstract class for common fields, define namespace for object, file Xml.java
package example.xml;
#XmlTransient
public abstract class Xml {
private Header header;
private Customer customer;
#XmlElement(namespace="http://www.example.org/header")
public Header getHeader() {
return header;
}
public void setHeader(Header header) {
this.header = header;
}
#XmlElement(namespace="http://www.example.org/customer")
public Customer getCustomer() {
return customer;
}
public void setCustomer(Customer customer) {
this.customer = customer;
}
}
Create "root" class, XmlBoo.java
package example.xml.boo;
#XmlRootElement
#XmlType(propOrder = {"header", "customer", "someBooSpecificField"})
public class XmlBoo extends Xml {
private String someBooSpecificField;
// getter & setter
}
Set namespace and QUALIFIED for "root" class, file: example.xml.boo.package-info.java
#XmlSchema(
namespace = "http://www.example.org/boo",
elementFormDefault = XmlNsForm.QUALIFIED)
package example.xml.boo;
Set QUALIFIED to generate prefix for children (the namespace will be overridden by namespace defined on the class, but it must be defined), file: example.model.package-info.java
#XmlSchema(
namespace = "http://www.example.org",
elementFormDefault = XmlNsForm.QUALIFIED)
package example.model;
Create Header.java
package example.model;
#XmlType(namespace = "http://www.example.org/header")
public class Header {
private long id;
// getter & setter
}
Create Customer.java
package example.model;
#XmlType(namespace = "http://www.example.org/customer", propOrder = {"id", "name", "address"})
public class Customer {
private long id;
private String name;
private Address address;
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
#XmlElement(namespace="http://www.example.org/address")
public Address getAddress() {
return address;
}
public void setAddress(Address address) {
this.address = address;
}
}
Create Address.java
package example.model;
#XmlType(namespace = "http://www.example.org/address")
public class Address {
private String street;
// getter & setter
}
Create MyNamespacePrefixMapper.java by extending org.eclipse.persistence.oxm.NamespacePrefixMapper
package example;
import org.eclipse.persistence.oxm.NamespacePrefixMapper;
public class MyNamespacePrefixMapper extends NamespacePrefixMapper {
private static final String BOO_PREFIX = ""; // DEFAULT NAMESPACE
private static final String BOO_URI = "http://www.example.org/boo";
private static final String FOO_PREFIX = ""; // DEFAULT NAMESPACE
private static final String FOO_URI = "http://www.example.org/foo";
private static final String HEADER_PREFIX = "h";
private static final String HEADER_URI = "http://www.example.org/header";
private static final String CUSTOMER_PREFIX = "c";
private static final String CUSTOMER_URI = "http://www.example.org/customer";
private static final String ADDRESS_PREFIX = "a";
private static final String ADDRESS_URI = "http://www.example.org/address";
#Override
public String getPreferredPrefix(String namespaceUri, String suggestion, boolean requirePrefix) {
switch (namespaceUri) {
case BOO_URI:
return BOO_PREFIX;
case FOO_URI:
return FOO_PREFIX;
case HEADER_URI:
return HEADER_PREFIX;
case CUSTOMER_URI:
return CUSTOMER_PREFIX;
case ADDRESS_URI:
return ADDRESS_PREFIX;
default:
return null;
}
}
}
Create XML
public static void generateBoo() {
try {
JAXBContext jc = JAXBContext.newInstance(XmlBoo.class);
Marshaller m = jc.createMarshaller();
m.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
m.setProperty(MarshallerProperties.NAMESPACE_PREFIX_MAPPER, new MyNamespacePrefixMapper());
XmlBoo xmlBoo = new XmlBoo();
Header header = new Header();
header.setId(101);
xmlBoo.setHeader(header);
Customer customer = new Customer();
customer.setId(1);
customer.setName("Yen");
Address address = new Address();
address.setStreet("Long street");
customer.setAddress(address);
xmlBoo.setCustomer(customer);
xmlBoo.setSomeBooSpecificField("Specific data in Boo");
m.marshal(xmlBoo, System.out);
m.marshal(xmlBoo, new File("xml_boo.xml"));
} catch (JAXBException e) {
e.printStackTrace();
}
}
Read XML
public static void readBoo() {
Object element = null;
try {
JAXBContext jc = JAXBContext.newInstance(XmlBoo.class);
Unmarshaller u = jc.createUnmarshaller();
element = u.unmarshal(new File("xml_boo.xml"));
} catch (JAXBException e) {
e.printStackTrace();
}
if (element instanceof XmlBoo) {
XmlBoo xmlBoo = (XmlBoo) element;
Customer customer = xmlBoo.getCustomer();
System.out.println("INFO | xmlBoo field: [" + xmlBoo.getSomeBooSpecificField() + "]");
System.out.println("INFO | customer name: [" + customer.getName() + "]");
System.out.println("INFO | address street: [" + customer.getAddress().getStreet() + "]");
}
}

I used EclipseLink MOXy JAXB implementation instead of RI Metro JAXB and now it works. So it looks that in Metro is bug.
Perfect tutorial by Blaise Doughan: JAXB & Namespace prefixes

You will need to have a package-info annotation with a #XmlSchema annotation for each package in your domain model each specifying the same namespace qualification to get the desired XML.