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How to use setters in JAXB collections unmarshalling

I wan't to deserialize XML to my POJO but something doing wrong...
My POJO class:
#Builder
#ToString
#AllArgsConstructor
#NoArgsConstructor
#XmlRootElement(name="taxi")
#XmlAccessorType(XmlAccessType.PROPERTY)
#XmlType(propOrder = {"id", "name", "phone", "citiesId"})
public class TaxiEntity {
#Getter #Setter
private Integer id;
#Getter #Setter
private String name;
#Getter #Setter
private String phone;
#Singular("city")
private Set<Integer> citiesId = new HashSet<>();
#XmlElementWrapper(name="cities_id")
#XmlElement(name="city_id")
public void setCitiesId(Set<Integer> citiesId) {
System.out.println("setCitiesId()");
this.citiesId = citiesId;
}
public Set<Integer> getCitiesId() {
System.out.println("getCitiesId()");
return new HashSet<>(citiesId);
}
}
Marshalling example:
JAXBContext context = JAXBContext.newInstance(TaxiEntity.class);
TaxiEntity entity = TaxiEntity.builder().
id(5).
name("my city").
phone("12345678").
city(1).
city(5).
build();
Marshaller marshaller = context.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
marshaller.marshal(entity, new File("entity.xml"));
XML output:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<taxi>
<id>5</id>
<name>my city</name>
<phone>12345678</phone>
<cities_id>
<city_id>1</city_id>
<city_id>5</city_id>
</cities_id>
</taxi>
Unmarshalling example:
JAXBContext context = JAXBContext.newInstance(TaxiEntity.class);
Unmarshaller unmarshaller = context.createUnmarshaller();
TaxiEntity entity = (TaxiEntity) unmarshaller.unmarshal(new File("entity.xml"));
System.out.println(entity);
Console output:
getCitiesId()
getCitiesId()
TaxiEntity(id=5, name=my city, phone=12345678, citiesId=[])
Process finished with exit code 0
As you can see, citiesId is empty.
It happens because JAXB unmarshalling calling the getter (copy of field in my case)
and trying to set values into a copy of collection.
How to make it create a collection and set it via setter?
P.S. In my real bussiness object, i have collect IDs in getter from DB entities, and cannot return collection in getter.
Thanks!

---- Edited last time -----
import java.io.File;
import java.util.Set;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlElementWrapper;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlType;
import lombok.Builder;
import lombok.Singular;
import lombok.ToString;
#Builder
#ToString
#XmlRootElement(name = "taxi")
#XmlType(name="taxi", propOrder = { "id", "name", "phone", "citiesId" })
public class TaxiEntity {
private Integer id;
private String name;
private String phone;
#Singular("city")
private Set<Integer> citiesId;
public TaxiEntity() {
}
public TaxiEntity(Integer id, String name, String phone, Set<Integer> citiesId) {
System.out.println("Hello");
this.id = id;
this.name = name;
this.phone = phone;
this.citiesId = citiesId;
}
#XmlElementWrapper(name = "cities_id")
#XmlElement(name = "city_id")
public void setCitiesId(Set<Integer> citiesId) {
System.out.println("I should be calling during deserialization" + citiesId);
this.citiesId = citiesId;
}
#XmlElement
public void setId(Integer id) {
this.id = id;
}
#XmlElement
public void setName(String name) {
this.name = name;
}
#XmlElement
public void setPhone(String phone) {
this.phone = phone;
}
public Integer getId() {
return id;
}
public String getName() {
return name;
}
public String getPhone() {
return phone;
}
public Set<Integer> getCitiesId() {
System.out.println("Calling getter " + this.citiesId);
return citiesId;
}
public static void main(String[] args) {
try {
JAXBContext context = JAXBContext.newInstance(TaxiEntity.class);
Marshaller marshaller = context.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
Unmarshaller unmarshaller = context.createUnmarshaller();
TaxiEntity entity = TaxiEntity.builder().id(5).name("my city").phone("12345678").city(1).city(5).build();
marshaller.marshal(entity, new File("C:/whee/entity.xml"));
System.out.println("Unmarshalling now ------");
TaxiEntity taxEntityWithSettersGetters = (TaxiEntity) unmarshaller.unmarshal(new File("C:/whee/entity.xml"));
System.out.println(taxEntityWithSettersGetters);
} catch (Exception e) {
e.printStackTrace();
}
}
Printout:
Hello
Calling getter [1, 5]
Unmarshalling now ------
Calling getter null
I should be calling during deserialization[]
Calling getter [1, 5]
TaxiEntity(id=5, name=my city, phone=12345678, citiesId=[1, 5])
During unmarshalling JAXB checks if your collection is null, if it is (It will call the setter for the first time to initialize it to empty), and you can see that in the log.
However, afterwards, it will use its internal logic to populate the collection (SET), initialize its type (New Set)*by using the Setter you have, and use the Set.add(xyz); to add (1), then (5).
The JAXB Logic invoked is found in class:
public abstract class Lister<BeanT,PropT,ItemT,PackT> {
//startPacking is calling to initialize the collection Set so it is empty
public T startPacking(BeanT bean, Accessor<BeanT, T> acc) throws AccessorException {
T collection = acc.get(bean);
if(collection==null) {
collection = ClassFactory.create(implClass);
if(!acc.isAdapted())
acc.set(bean,collection);
}
collection.clear();
return collection;
}
//Right way, this gets called afterwards (Before any of your TaxiEntity logic), to do addToPack(1), addToPack(5), <--- Now your Set has [1,5]
public void addToPack(T collection, Object o) {
collection.add(o);
}
Then, you see in the log, it calls getCitiesIds(), and you will see magically it has [1,5]
Its the way JAXB works with Collections. All other elements, their proper Setters are called.
See, JAXB does not call Setter method
You need to think of a different way of doing it, rather than dependending on the getter/setter. It did its job of unmarshalling the object from the XML file, the rest of the logic could be written in an external method.

JAXB unmarshalling without XmlRootElement annotation?

Is there any way we can un-marshall for a class without #XmlRootElement annotation? Or are we obligated to enter the annotation?
for example:
public class Customer {
private String name;
private int age;
private int id;
public String getName() {
return name;
}
#XmlElement
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
#XmlElement
public void setAge(int age) {
this.age = age;
}
public int getId() {
return id;
}
#XmlAttribute
public void setId(int id) {
this.id = id;
}
}
and let the unmarshalling code for properly annotated class be like:
try {
File file = new File("C:\\file.xml");
JAXBContext jaxbContext = JAXBContext.newInstance(Customer.class);
Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();
Customer customer = (Customer) jaxbUnmarshaller.unmarshal(file);
System.out.println(customer);
} catch (JAXBException e) {
e.printStackTrace();
}
leaving out the details.

Following code is used to marshall and unmarshall withot #XmlRootElement
public static void main(String[] args) {
try {
StringWriter stringWriter = new StringWriter();
Customer c = new Customer();
c.setAge(1);
c.setName("name");
JAXBContext jaxbContext = JAXBContext.newInstance(Customer.class);
Marshaller marshaller = jaxbContext.createMarshaller();
marshaller.marshal(new JAXBElement<Customer>( new QName("", "Customer"), Customer.class, null, c), stringWriter);
Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();
InputStream is = new ByteArrayInputStream(stringWriter.toString().getBytes());
JAXBElement<Customer> customer = (JAXBElement<Customer>) jaxbUnmarshaller.unmarshal(new StreamSource(is),Customer.class);
c = customer.getValue();
} catch (JAXBException e) {
e.printStackTrace();
}
}
Above code works only if you adding #XmlAccessorType(XmlAccessType.PROPERTY) on Customer class, or make private all attributes.

If you cannot add XmlRootElement to existing bean you can also create a holder class and mark it with annotation as XmlRootElement. Example below:-
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlRootElement;
#XmlRootElement
#XmlAccessorType(XmlAccessType.FIELD)
public class CustomerHolder
{
private Customer cusotmer;
public Customer getCusotmer() {
return cusotmer;
}
public void setCusotmer(Customer cusotmer) {
this.cusotmer = cusotmer;
}
}

It is indisputable that the question is very old for an answer, however still hoping someone like me is looking for a simple generic code snippet for the above requirement, hence sharing the working solution for the marshal and unmarshal need.
Marshalling XML object to String
public static <T> Optional<String> objectToXMLString(T value,Class<T> clazz,String rootElement) {
StringWriter sw = new StringWriter();
try {
JAXBContext jaxbContext = JAXBContext.newInstance(clazz);
Marshaller jaxbMarshaller = jaxbContext.createMarshaller();
JAXBElement<T> jaxbElement = new JAXBElement<>(new QName(rootElement), clazz,value);
jaxbMarshaller.marshal(jaxbElement, sw);
return Optional.of(sw.toString());
} catch (JAXBException e) {
LOGGER.error("XML to String Conversion exception:{}", e.getMessage(), e);
}
return Optional.empty();
}
UnMarshalling String to XML object
public static <T> Optional<T> xmlStringToObject(String value, Class<T> clazz) {
try {
JAXBContext jaxbContext = JAXBContext.newInstance(clazz);
Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();
InputStream is = new ByteArrayInputStream(value.getBytes());
JAXBElement<T> object = unmarshaller.unmarshal(new StreamSource(is),clazz);
return Optional.of(object.getValue());
} catch (JAXBException e) {
LOGGER.error("String to XML Conversion exception : {}", e.getMessage(), e);
}
return Optional.empty();
}

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.

My web service throwing exception:javax.xml.bind.JAXBException: class [Ljava.lang.String; nor any of its super class is known to this context [duplicate]

I'm trying to marshal an object that has an Object as one of its fields.
#XmlRootElement
public class TaskInstance implements Serializable {
...
private Object dataObject;
...
}
The dataObject can be one of many different unknown types, so specifying each somewhere is not only impractical but impossible. When I try to marshal the object, it says the class is not known to the context.
MockProcessData mpd = new MockProcessData();
TaskInstance ti = new TaskInstance();
ti.setDataObject(mpd);
String ti_m = JAXBMarshall.marshall(ti);
"MockProcessData nor any of its super class is known to this context." is what I get.
Is there any way around this error?

JAXB cannot marshal any old object, since it doesn't know how. For example, it wouldn't know what element name to use.
If you need to handle this sort of wildcard, the only solution is to wrap the objects in a JAXBElement object, which contains enough information for JAXB to marshal to XML.
Try something like:
QName elementName = new QName(...); // supply element name here
JAXBElement jaxbElement = new JAXBElement(elementName, mpd.getClass(), mpd);
ti.setDataObject(jaxbElement);

Method:
public String marshallXML(Object object) {
JAXBContext context;
try {
context = JAXBContext.newInstance(object.getClass());
StringWriter writer = new StringWriter();
Marshaller marshaller = context.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
marshaller.marshal(object, writer);
String stringXML = writer.toString();
return stringXML;
} catch (JAXBException e) {
}
}
Model:
import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
#XmlRootElement
public class Customer {
String name;
int id;
public String getName() {
return name;
}
#XmlElement
public void setName(String name) {
this.name = name;
}
public int getId() {
return id;
}
#XmlAttribute
public void setId(int id) {
this.id = id;
}
}