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#XmlElement with multiple names

I have a situation here, trying to act as a gateway between two APIs. What I need to do, is:
make a request to an APIa;
parse (marshal) the XML response into an java object;
make little changes to it;
and then give a response in XML (unmarshal) to the other end (APIb).
The thing is that I use the same object to parse the API response and to send the response to the other end.
public class ResponseAPI{
#XmlElement(name="ResponseCode") //I receive <ResponseCode> but I need to send <ResultCode>
private String responseCode;
//getter and setter
}
as the comment says: I receive but I need to send
Is there a way to get this done without having to create another extra class which carries ResultCode?
thanks in advance!

You can try next solution using #XmlElements annotaion
#XmlAccessorType(XmlAccessType.FIELD)
public class ResponseAPI
{
#XmlElements(
{
#XmlElement(name = "ResponseCode"),
#XmlElement(name = "ResultCode")
})
private String responseCode;
// ...
}
In this case both ResponseCode and ResultCode will be used during unmarshalling (xml -> object) and only ResultCode during marshalling (object -> xml).
So you can unmarshall XML like
<responseAPI>
<ResponseCode>404</ResponseCode>
</responseAPI>
After marshalling object will looks like
<responseAPI>
<ResultCode>404</ResultCode>
</responseAPI>

Note:
The answer given by Ilya works but isn't guaranteed to work across all implementations of JAXB or even across versions of a single JAXB implementation. The #XmlElements annotation is useful when the decision of which element to marshal depends on the type of the value (see: http://blog.bdoughan.com/2010/10/jaxb-and-xsd-choice-xmlelements.html). In your use case both the ResponseCode and ResultCode elements correspond to type String, unmarshalling will always work fine, but the choice of which element to output is arbitrary. Some JAXB Impls may have last specified wins, but others could easily have first wins.
You could do the following by leveraging #XmlElementRef.
Java Model
ResponseAPI
We will change the responseCode property from type String to JAXBElement<String>. The JAXBElement allows us to store the element name as well as the value.
import javax.xml.bind.JAXBElement;
import javax.xml.bind.annotation.*;
#XmlRootElement
#XmlAccessorType(XmlAccessType.FIELD)
public class ResponseAPI{
#XmlElementRefs({
#XmlElementRef(name = "ResponseCode"),
#XmlElementRef(name = "ResultCode")
})
private JAXBElement<String> responseCode;
public JAXBElement<String> getResponseCode() {
return responseCode;
}
public void setResponseCode(JAXBElement<String> responseCode) {
this.responseCode = responseCode;
}
}
ObjectFactory
The #XmlElementRef annotations we used on the ResponseAPI class correspond to #XmlElementDecl annotations on a class annotated with #XmlRegistry. Traditionally this class is called ObjectFactory but you can call it anything you want.
import javax.xml.bind.JAXBElement;
import javax.xml.bind.annotation.*;
import javax.xml.namespace.QName;
#XmlRegistry
public class ObjectFactory {
#XmlElementDecl(name="ResponseCode")
public JAXBElement<String> createResponseCode(String string) {
return new JAXBElement<String>(new QName("ResponseCode"), String.class, string);
}
#XmlElementDecl(name="ResultCode")
public JAXBElement<String> createResultCode(String string) {
return new JAXBElement<String>(new QName("ResultCode"), String.class, string);
}
}
Demo Code
input.xml
<responseAPI>
<ResponseCode>ABC</ResponseCode>
</responseAPI>
Demo
When creating the JAXBContext we need to ensure that we include the class that contains the #XmlElementDecl annotations.
import java.io.File;
import javax.xml.bind.*;
public class Demo {
public static void main(String[] args) throws Exception {
JAXBContext jc = JAXBContext.newInstance(ResponseAPI.class, ObjectFactory.class);
Unmarshaller unmarshaller = jc.createUnmarshaller();
File xml = new File("Scratch/src2/forum24554789/input.xml");
ResponseAPI responseAPI = (ResponseAPI) unmarshaller.unmarshal(xml);
ObjectFactory objectFactory = new ObjectFactory();
String responseCode = responseAPI.getResponseCode().getValue();
JAXBElement<String> resultCodeJAXBElement = objectFactory.createResultCode(responseCode);
responseAPI.setResponseCode(resultCodeJAXBElement);
Marshaller marshaller = jc.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
marshaller.marshal(responseAPI, System.out);
}
}
Output
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<responseAPI>
<ResultCode>ABC</ResultCode>
</responseAPI>

How can JAXB XmlAdapter be used to marshall lists?

Instances of this class are part of a large object graph and are not at the root of the object graph:
public class Day
{
public Day(LocalDate date, List<LocalTime> times)
{
this.date = date;
this.times = times;
}
public Day()
{
this(null, null);
}
public LocalDate getDate()
{
return date;
}
public List<LocalTime> getTimes()
{
return times;
}
private final LocalDate date;
private final List<LocalTime> times;
}
The object graph is converted to JSON using Jersey and JAXB. I have XmlAdapters registered for LocalDate and LocalTime.
The problem is that it's only working for the date property and not the times property. I suspect this has something to do with the fact that times is a list rather than a single value. How, then, do I tell Jersey/JAXB to marshall each element in the times list using the registered XmlAdapter?
Update:
I confirmed that LocalTime marshalling is indeed working for scalar LocalTime properties by adding a scalar LocalTime property and observing the expected output in the JSON.
For completeness, here's package-info.java:
#XmlJavaTypeAdapters({
#XmlJavaTypeAdapter(value = LocalDateAdapter.class, type = LocalDate.class),
#XmlJavaTypeAdapter(value = LocalTimeAdapter.class, type = LocalTime.class)
})
package same.package.as.everything.else;
LocalDateAdapter:
public class LocalDateAdapter extends XmlAdapter<String, LocalDate>
{
#Override
public LocalDate unmarshal(String v) throws Exception
{
return formatter.parseLocalDate(v);
}
#Override
public String marshal(LocalDate v) throws Exception
{
return formatter.print(v);
}
private final DateTimeFormatter formatter = DateTimeFormat.forPattern("yyyyMMdd");
}
LocalTimeAdapter:
public class LocalTimeAdapter extends XmlAdapter<String, LocalTime>
{
#Override
public LocalTime unmarshal(String v) throws Exception
{
return formatter.parseLocalTime(v);
}
#Override
public String marshal(LocalTime v) throws Exception
{
return formatter.print(v);
}
private final DateTimeFormatter formatter = DateTimeFormat.forPattern("HHmm");

An XmlAdapter for a class is applied to a mapped field/property of that type, and in the case of collections, for each item in the collection. The example below proves that this works. Have you tried running your example standalone to XML to verify the mappings that way. Is suspect the problem is something else other than the XmlAdapter specifically.
StringAdapter
The following XmlAdapter will convert a String to lower case on the unmarshal operation and convert it to upper case when marshalled.
package forum14569293;
import javax.xml.bind.annotation.adapters.XmlAdapter;
public class StringAdapter extends XmlAdapter<String, String> {
#Override
public String unmarshal(String v) throws Exception {
return v.toLowerCase();
}
#Override
public String marshal(String v) throws Exception {
return v.toUpperCase();
}
}
package-info
Just as in your question a package level #XmlJavaTypeAdapters annotation will be used to register the XmlAdapter. This will register this XmlAdapter for all mapped String properties within this package (see: http://blog.bdoughan.com/2012/02/jaxb-and-package-level-xmladapters.html).
#XmlJavaTypeAdapters({
#XmlJavaTypeAdapter(value=StringAdapter.class, type=String.class)
})
package forum14569293;
import javax.xml.bind.annotation.adapters.*;
Root
Below is a sample domain model similar to your Day class with two mapped properties. The first is of type String and the second List<String>. One thing I notice about your Day class is that you only have get methods. This means that you will need to add an #XmlElement annotation for a JAXB impl to consider that a mapped property.
package forum14569293;
import java.util.*;
import javax.xml.bind.annotation.*;
#XmlRootElement
public class Root {
public Root(String foo, List<String> bar) {
this.foo = foo;
this.bar = bar;
}
public Root() {
this(null, null);
}
#XmlElement
public String getFoo() {
return foo;
}
#XmlElement
public List<String> getBar() {
return bar;
}
private final String foo;
private final List<String> bar;
}
Demo
package forum14569293;
import java.util.*;
import javax.xml.bind.*;
public class Demo {
public static void main(String[] args) throws Exception {
JAXBContext jc = JAXBContext.newInstance(Root.class);
List<String> bar = new ArrayList<String>(3);
bar.add("a");
bar.add("b");
bar.add("c");
Root root = new Root("Hello World", bar);
Marshaller marshaller = jc.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
marshaller.marshal(root, System.out);
}
}
Output
Below is the output from running the demo code we see that all the strings were converted to upper case by the XmlAdapter.
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<root>
<bar>A</bar>
<bar>B</bar>
<bar>C</bar>
<foo>HELLO WORLD</foo>
</root>
UPDATE
Thanks. I tried it and the XML consisted of one empty tag only,
meaning there's something about the POJO model that JAXB doesn't like.
(Perhaps it should be Serializable?)
JAXB does not require that POJOs implement Serializable.
That's interesting because it seems to indicate that the only part
JAXB plays in this is to lend its annotations and some other
interfaces (e.g. XmlAdapter) to the JSON (de)serializer and that's
where the relationship ends.
It depends on what is being used as the JSON binding layer. The JAXB (JSR-222) specification does not cover JSON-binding so this type of support is beyond the spec. EclipseLink JAXB (MOXy) offers native JSON-binding (I'm the MOXy lead) with it you could do something like:
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(root, System.out);
And get the following output that takes the XmlAdapter into account:
{
"bar" : [ "A", "B", "C" ],
"foo" : "HELLO WORLD"
}
Nevertheless, when I get an opportunity I will do what I can to get
JAXB to generate the XML and that may reveal something else.
This would be useful as I do not believe what you are seeing is a JAXB issue, but an issue in the JSON binding layer that you are using.

Can jaxb resolve system properties?

We use JAXB to configure object with XML. I was wondering if there is a way that JAXB could resolve system property. For instance, if I have a bean with property color, I would like to be able to do that:
<mybean color="${mycolor.in.data.property}" />
But if I do that, JAXB create the mybean object an color will be equals to the string:
mycolor.in.data.property
Is there is any equivalent of the PropertyPlaceholderConfigurer in spring for JAXB, so that my system property could be resolved?

An XmlAdapter is a JAXB (JSR-222) mechanism that allows you to convert an object to another object during marshalling/unmarshaller. You could write an XmlAdapter that converts the system property name to the real value.
import javax.xml.bind.annotation.adapters.XmlAdapter;
public class ColorAdapter extends XmlAdapter<String, String> {
#Override
public String unmarshal(String v) throws Exception {
return System.getProperty(v);
}
#Override
public String marshal(String v) throws Exception {
return v;
}
}
Then you use the #XmlJavaTypeAdapter annotation to configure the XmlAdapter for your property.
#XmlJavaTypeAdapter(ColorAdapter.class)
public String getColor() {
return color;
}
For More Information
http://blog.bdoughan.com/2011/05/jaxb-and-joda-time-dates-and-times.html
UPDATE
Ok thanks. Actually I do not have access to the class, as this is part
of an imported library. So I was more looking of a way to configure
this directly in the xml file, but it is probably not possible.
If you can't modify the class, then you can use a StreamReaderDelegate to modify the XML input. There a few methods that deal with the text/character data so you may need to experiment to be sure that you are overriding the one that works best with the JAXB implementation you are using.
import javax.xml.bind.*;
import javax.xml.stream.*;
import javax.xml.stream.util.StreamReaderDelegate;
import javax.xml.transform.stream.StreamSource;
public class Demo {
public static void main(String[] args) throws Exception {
JAXBContext jc = JAXBContext.newInstance(MyBean.class);
XMLInputFactory xif = XMLInputFactory.newFactory();
StreamSource source = new StreamSource("input.xml");
XMLStreamReader xsr = xif.createXMLStreamReader(source);
xsr = new StreamReaderDelegate(xsr) {
#Override
public String getText() {
String text = super.getText();
if(text.contains("${")) {
text = System.getProperty(text);
}
return text;
}
};
Unmarshaller unmarshaller = jc.createUnmarshaller();
unmarshaller.unmarshal(xsr);
}
}

Is there any Java support for JSPON serialization with references?

I'm looking for a Java JSPON serializer that can handle references according to the JSPON specification.
Are there any available that can do this currently? Or is there any way to modify an existing serializer to handle object refs with the $ref notation?

Note: I'm the EclipseLink JAXB (MOXy) lead and a member of the JAXB 2 (JSR-222) expert group.
If you are interested in an object-JSON binding approach, below is how it could be done using MOXy. The example below is based on the example one from the JSPON Core Spec:
http://www.jspon.org/JSPON_Core_Spec.htm
Parent
The Parent class is the domain object that corresponds to the root of the JSON message. It has two fields that are of type Child.
package forum9862100;
import javax.xml.bind.annotation.*;
#XmlAccessorType(XmlAccessType.FIELD)
public class Parent {
protected Child field1;
protected Child field2;
}
Child
The Child class may be referenced by its key. We will handle this use case with an XmlAdapter. We link to an XmlAdapter via the #XmlJavaTypeAdapter annotation.
package forum9862100;
import javax.xml.bind.annotation.*;
import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
#XmlJavaTypeAdapter(ChildAdapter.class)
#XmlAccessorType(XmlAccessType.FIELD)
public class Child {
protected String id;
protected String foo;
protected Integer bar;
}
ChildAdapter
Below is the implementation of the XmlAdapter. This XmlAdapter is stateful which means we will need to set an instance on the Marshaller and Unmarshaller.
package forum9862100;
import java.util.*;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.adapters.XmlAdapter;
public class ChildAdapter extends XmlAdapter<ChildAdapter.AdaptedChild, Child>{
private List<Child> childList = new ArrayList<Child>();
private Map<String, Child> childMap = new HashMap<String, Child>();
public static class AdaptedChild extends Child {
#XmlElement(name="$ref")
public String reference;
}
#Override
public AdaptedChild marshal(Child child) throws Exception {
AdaptedChild adaptedChild = new AdaptedChild();
if(childList.contains(child)) {
adaptedChild.reference = child.id;
} else {
adaptedChild.id = child.id;
adaptedChild.foo = child.foo;
adaptedChild.bar = child.bar;
childList.add(child);
}
return adaptedChild;
}
#Override
public Child unmarshal(AdaptedChild adaptedChild) throws Exception {
Child child = childMap.get(adaptedChild.reference);
if(null == child) {
child = new Child();
child.id = adaptedChild.id;
child.foo = adaptedChild.foo;
child.bar = adaptedChild.bar;
childMap.put(child.id, child);
}
return child;
}
}
Demo
The code below demonstrates how to specify a stateful XmlAdapter on the Marshaller and Unmarshaller:
package forum9862100;
import java.io.File;
import javax.xml.bind.*;
import javax.xml.transform.stream.StreamSource;
public class Demo {
public static void main(String[] args) throws Exception {
JAXBContext jc = JAXBContext.newInstance(Parent.class);
StreamSource json = new StreamSource(new File("src/forum9862100/input.json"));
Unmarshaller unmarshaller = jc.createUnmarshaller();
unmarshaller.setProperty("eclipselink.media-type", "application/json");
unmarshaller.setProperty("eclipselink.json.include-root", false);
unmarshaller.setAdapter(new ChildAdapter());
Parent parent = (Parent) unmarshaller.unmarshal(json, Parent.class).getValue();
System.out.println(parent.field1 == parent.field2);
Marshaller marshaller = jc.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
marshaller.setProperty("eclipselink.media-type", "application/json");
marshaller.setProperty("eclipselink.json.include-root", false);
marshaller.setAdapter(new ChildAdapter());
marshaller.marshal(parent, System.out);
}
}
Output
Below is the output from running the demo code. Note how the two instances of Child pass the identity test.
true
{
"field1" : {
"id" : "2",
"foo" : "val",
"bar" : 4
},
"field2" : {
"$ref" : "2"
}}
For More Information
http://blog.bdoughan.com/2011/09/mixing-nesting-and-references-with.html
http://blog.bdoughan.com/2011/08/json-binding-with-eclipselink-moxy.html

I would use one of the many Object to JSon serialization libraries. Many of the libraries are extensible, but I suspect adding references could get complicated unless you make some pragmatic choices as to when to use these.

How can I marshall a single java bean into a complex XML document with existing annotations?

I have a single java bean, which is already annotated for JPA, that I also wish to store as XML, specifically FIXML. The goal is to manage the mapping from bean to XML with annotations.
I see related topics online about specifying a schema and letting JAXB generate classes, but I don't want to do that.
I've been looking at using JAXB annotations, but it seems that I'll need to make new classes for each child element. I'm trying to stay away from that, and let the annotations show how to construct the child elements. JAXB does not seem to want to do this.
Is this possible, and how? Do I need to make my own annotations and forget about JAXB?
Concrete example
Bean:
#Entity
#XmlRootElement(name="FIXML")
#XmlType(name="ExecRpt")
public class ExecutionReport implements Serializable {
private String account;
private String senderCompID;
#Column(name="ACCOUNT", nullable=true, length=64)
#XmlAttribute(name="Acct")
public String getAccount() {
return this.account;
}
public void setAccount(String account) {
this.account = account;
}
#Column(name="SENDER_COMP_ID", nullable=true, length=200)
#XmlAttribute(name="SID")
public String getSenderCompID() {
return this.senderCompID;
}
public void setSenderCompID(String senderCompID) {
this.senderCompID = senderCompID;
}
}
Parsing:
JAXBContext context = JAXBContext.newInstance(ExecutionReport.class);
Marshaller marshaller = context.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true); //pretty print XML
marshaller.marshal(executionReport, System.out);
Desired resulting XML:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<FIXML>
<ExecRpt Acct="account_data">
<Hdr SID="sender"/>
</ExecRpt>
</FIXML>
Current resulting XML:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<FIXML Acct="account_data" SID="sender"/>
Clearly I'm not providing enough information to map the child elements yet, but I'm also not sure how to provide it. I want to add some #XmlElement annotations, but I don't have child objects, all the data is in this class.
The upside is that my XML isn't much more complicated than this example; there are only a handful of elements, and they only appear once per message. The thing that's giving me trouble is getting multiple elements out of a single bean.

You can use the #XmlPath extension in EclipseLink JAXB (MOXy) for this, I'm the tech lead.
Model Class
import java.io.Serializable;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlType;
import org.eclipse.persistence.oxm.annotations.XmlPath;
#Entity
#XmlRootElement(name="FIXML")
#XmlType(name="ExecRpt")
public class ExecutionReport implements Serializable {
private String account;
private String senderCompID;
#Column(name="ACCOUNT", nullable=true, length=64)
#XmlPath("ExecRpt/#Acct")
public String getAccount() {
return this.account;
}
public void setAccount(String account) {
this.account = account;
}
#Column(name="SENDER_COMP_ID", nullable=true, length=200)
#XmlPath("ExecRpt/Hdr/#SID")
public String getSenderCompID() {
return this.senderCompID;
}
public void setSenderCompID(String senderCompID) {
this.senderCompID = senderCompID;
}
}
Demo Code
import javax.xml.bind.JAXBContext;
import javax.xml.bind.Marshaller;
public class Demo {
public static void main(String[] args) throws Exception {
JAXBContext jc = JAXBContext.newInstance(ExecutionReport.class);
ExecutionReport er = new ExecutionReport();
er.setAccount("account_data");
er.setSenderCompID("sender");
Marshaller marshaller = jc.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
marshaller.marshal(er, System.out);
}
}
Resulting XML
<?xml version="1.0" encoding="UTF-8"?>
<FIXML>
<ExecRpt Acct="account_data">
<Hdr SID="sender"/>
</ExecRpt>
</FIXML>
Specifying the EclipseLink JAXB (MOXy) Implementation
To specify MOXy as the JAXB implementation you need to add a file called jaxb.properties in with your ExecutionReport class with the following entry:
javax.xml.bind.context.factory=org.eclipse.persistence.jaxb.JAXBContextFactory
For More Information
http://bdoughan.blogspot.com/2010/09/xpath-based-mapping-geocode-example.html

I don't know Jaxb annotations but if you ask for an attribute in ExecRpt it seems normal to have an attribute in ExecRpt no?
I think you expect a bit too much of these annotations. Don't you also want an annotation that would take a string, split it with a separator and generate a list of child elements or something?
And it seems to me a bad design to put these annotations directly on JPA entities. One day you could have to do some database changes for performances issues for exemple and you could not be able to generate the xml you want anymore. Why not transforming your jpa entity to a given structure jaxb friendly so that you keep the db and marshalling appart? Thus on change you would just have to modify the transformer.