I want to unmarshal xml content like this:
JAXBContext context = JAXBContext.newInstance(Node.class);
String input = "<item><d>foo</d></item>";
StreamSource istream = new StreamSource(new StringReader(input));
JAXBElement<Node> node = context.createUnmarshaller().unmarshal(istream, Node.class);
System.out.println(node.getValue().toString());
The d element cannot be trivially converted into the desired object, here a Boolean, so I use a setter method for that.
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
#XmlRootElement(name = "item")
public class Node {
#XmlElement(name = "d")
private Boolean value;
public void setValue(String d) {
this.value = d.equals("") ? Boolean.TRUE : Boolean.FALSE;
}
#Override
public String toString() {
return value.toString();
}
}
The XmlAnnotaion can be at setValue as well however when I add a getter method it has to be at the field(otherwise there is no parse and value remains null).
public Boolean getValue() {return value;}
But if instead of foo the value starts with a digit or a special character, say ?, there is again no parse.
Summary of effects:
annotation at field + no getter -> parses foo
annotation at setter + no getter -> parses foo and 0foo
annotation at field + getter -> parses foo
annotation at setter + getter -> parses neither
How do I need do set the annotations so that I can parse arbitrary values in d and why does it work here for strings that start with a letter?
Because XML is a typed language, and the types of the getter and setter need to match.
If. this is like, a real thing you're getting paid to do then you need to go and spend some time reading the jaxb documentation and probably the xml schema documentation.
here's some code because why not.
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Unmarshaller;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
#XmlRootElement(name = "item")
public class Node {
private Boolean value;
#XmlElement(name = "d", nillable = true, required = false)
public void setValue(String d) {
this.value = "".equals(d) ? Boolean.TRUE : Boolean.FALSE;
}
public String getValue(String d) {
return String.valueOf(value);
}
public boolean isValue() {
return Boolean.TRUE.equals(value);
}
#Override
public String toString() {
return "[Node|value=" + value + "]";
}
public static void main(String... args) {
try {
JAXBContext jaxbContext = JAXBContext.newInstance(Node.class);
Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();
Node node = (Node) jaxbUnmarshaller.unmarshal(new StringReader("<item><b></b></item>"));
System.out.println(node);
} catch (JAXBException e) {
e.printStackTrace();
}
}
}
Related
I want to explain my issue with a simple example:
Foo:
#SomeXMLAnnotations
public class Foo {
// Bar is just a random class with its own XML annotations
#XmlElement(required = true)
Bar someBarObj;
boolean chosen = true;
boolean required = true;
public Foo(){
chosen = false;
}
public Foo(Bar someBarObj){
this.someBarObj = someBarObj;
}
}
MyClass:
#SomeXMLAnnotations
public class MyClass {
#XmlElement(required = false)
Foo anyFooObj;
#XmlElement(required = true)
Foo anyFooObjRequired;
public MyClass (){ }
public MyClass (Foo anyFooObj, Foo anyFooObjRequired){
this.anyFooObj = anyFooObj;
if(anyFooObj == null)
this.anyFooObj = new Foo();
/*
* This is the reason why i can't let 'anyFooObj' be 'null'.
* So 'anyFooObj' MUST be initialized somehow.
* It's needed for some internal logic, not JAXB.
*/
anyFooObj.required = false;
this.anyFooObjRequired = anyFooObjRequired;
}
}
Example Objects:
Foo fooRequired = new Foo(new Bar());
MyClass myObj = new MyClass(null, fooRequired);
When i try to marshal myObj now, it throws an exception like this:
org.eclipse.persistence.oxm.record.ValidatingMarshalRecord$MarshalSAXParseException;
cvc-complex-type.2.4.b: The content of element 'n0:anyFooObj ' is not complete.
One of '{"AnyNamespace":someBarObj}' is expected.
This happens because anyFooObj is initialized but it's required, member
someBarObj isn't.
Possible Solution:
I know i could add this method to MyClass:
void beforeMarshal(Marshaller m){
if(! anyFooObj.chosen)
anyFooObj= null;
}
}
But I have a lot of classes and those classes have a lot of not required fields.
So this solution would take ages and doesn't look like a proper solution as well.
My Question:
Is there a way to tell JAXB that it should treat empty objects like they were null? Or that it should ignore an element when it's not properly set. Something like this for example:
#XmlElement(required = false, ingnoreWhenNotMarshallable = true)
Foo anyFooObj;
NOTE:
I'm NOT the developer of the code. I just have to add JAXB to the project and make everything compatible with a given XSD file. I'm NOT allowed to change the relation between classes.
I think you're trying to make the JAXB marshaller do something it's really not designed to do, so I'd say you're into hack territory here. I'd recommend pushing back on the requirements to try and avoid having this problem in the first place.
That said, if you have to do it then given your requirement to avoid writing code for each class/field, I think you'll want to use reflection for this - I've included an example below that reflectively inspects the values of all fields.
Useful extensions would be:
Have it consider getter methods too
Make the null-setting behaviour opt-in by requiring the field has an additional annotation - you could name it #JAXBNullIfEmpty
Example.java:
import javax.xml.bind.JAXBContext;
import javax.xml.bind.Marshaller;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
import java.io.StringWriter;
import java.lang.reflect.Field;
public class Example
{
public abstract static class JAXBAutoNullifierForEmptyOptionalFields
{
void beforeMarshal(Marshaller x)
{
try
{
for (Field field : this.getClass().getFields())
{
final XmlElement el = field.getAnnotation(XmlElement.class);
// If this is an optional field, it has a value & it has no fields populated then we should replace it with null
if (!el.required())
{
if (JAXBAutoNullifierForEmptyOptionalFields.class.isAssignableFrom(field.getType()))
{
final JAXBAutoNullifierForEmptyOptionalFields val = (JAXBAutoNullifierForEmptyOptionalFields) field.get(
this);
if (val != null && !val.hasAnyElementFieldsPopulated())
field.set(this, null); // No fields populated, replace with null
}
}
}
}
catch (IllegalAccessException e)
{
throw new RuntimeException("Error determining if class has all required fields: " + this, e);
}
}
boolean hasAnyElementFieldsPopulated()
{
for (Field field : this.getClass().getFields())
{
try
{
if (field.isAnnotationPresent(XmlElement.class))
{
// Retrieve value
final Object val = field.get(this);
// If the value is non-null then at least one field has been populated
if (val != null)
{
return true;
}
}
}
catch (IllegalAccessException e)
{
throw new RuntimeException("Error determining if class has any populated JAXB fields: " + this, e);
}
}
// There were no fields with a non-null value
return false;
}
}
#XmlRootElement
public static class MyJAXBType extends JAXBAutoNullifierForEmptyOptionalFields
{
#XmlElement
public String someField;
#XmlElement
public MyJAXBType someOtherField;
public MyJAXBType()
{
}
public MyJAXBType(final String someField, MyJAXBType someOtherField)
{
this.someField = someField;
this.someOtherField = someOtherField;
}
}
public static void main(String[] args) throws Exception
{
final Marshaller marshaller = JAXBContext.newInstance(MyJAXBType.class).createMarshaller();
MyJAXBType innerValue = new MyJAXBType(); // Unpopulated inner value
MyJAXBType value = new MyJAXBType("some text value", innerValue);
final StringWriter sw = new StringWriter();
marshaller.marshal(value, sw); // Omits "someOtherField"
System.out.println(sw.toString());
}
}
I've got this POJO, encapsulating a dynamic, non-nested element of an Atom entry:
public class SimpleElement {
private Namespace namespace;
private String tagName;
private String value;
private Collection<Attribute> attributes;
/* getters/setters/... */
And for completeness, Attribute
public class Attribute {
private String name;
private String value;
private Namespace namespace;
/* getters/setters/... */
And Namespace:
public class Namespace {
private final String uri;
private final String prefix;
/* getters/setters/... */
SimpleElementAdapter serializes a SimpleElement into its org.w3c.dom.Element counterpart.
The only problem with this approach is that namespaces always end up at element level, never at document root.
Is there a way to dynamically declare namespaces at document root?
MY RECOMMENDATION
My recommendation is to let the JAXB implementation write the namespace declarations as it sees fit. As long as the elements are properly namespace qualified it does not really matter where the namespace declarations occur.
If you ignore my recommendation, below is an approach you can use.
ORIGINAL ANSWER
Specify the Namespaces to Include on Root Element
You can use the NamespacePrefixMapper extension to add extra namespace declarations to the root element (see: https://jaxb.java.net/nonav/2.2.11/docs/ch05.html#prefixmapper). You will need to derive from your own object model what namespaces should be declared at the root.
Note: NamespacePrefixMapper is in the com.sun.xml.bind.marshaller package. This means you will need the JAXB refereince implementation jar on your classpath (see: https://jaxb.java.net/).
import com.sun.xml.bind.marshaller.*;
public class MyNamespacePrefixMapper extends NamespacePrefixMapper {
#Override
public String getPreferredPrefix(String arg0, String arg1, boolean arg2) {
return null;
}
#Override
public String[] getPreDeclaredNamespaceUris2() {
return new String[] {"ns1", "http://www.example.com/FOO", "ns2", "http://www.example.com/BAR"};
}
}
Specify the NamespacePrefixMapper on the Marshaller
The com.sun.xml.bind.namespacePrefixMapper property is used to specify the NamespacePrefixMapper on the Marshaller.
marshaller.setProperty("com.sun.xml.bind.namespacePrefixMapper", new MyNamespacePrefixMapper());
Demo Code
Java Model (Foo)
import javax.xml.bind.annotation.*;
#XmlRootElement
public class Foo {
private Object object;
#XmlAnyElement
public Object getObject() {
return object;
}
public void setObject(Object object) {
this.object = object;
}
}
Demo
import javax.xml.bind.*;
import javax.xml.parsers.*;
import org.w3c.dom.*;
import org.w3c.dom.Element;
public class Demo {
public static void main(String[] args) throws Exception {
JAXBContext jc = JAXBContext.newInstance(Foo.class);
Foo foo = new Foo();
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = dbf.newDocumentBuilder();
Document document = db.newDocument();
Element element = document.createElementNS("http://www.example.com/FOO", "ns1:foo");
foo.setObject(element);
Marshaller marshaller = jc.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
marshaller.setProperty("com.sun.xml.bind.namespacePrefixMapper", new MyNamespacePrefixMapper());
marshaller.marshal(foo, System.out);
}
}
Output
Below is sample output that will be produced:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<foo xmlns:ns1="http://www.example.com/FOO" xmlns:ns2="http://www.example.com/BAR">
<ns1:foo/>
</foo>
UPDATE
Clear answer, thanks. However, I need access to the NSMapper from
SimpleElementAdapter. What do you suggest? The only way I see right
now is making the NSMapper a mutable singleton so that
SimpleElementAdapter can add namespaces if needed.
I forgot about your XmlAdapter.
Java Model
Below is a more complicated iteration of the model, where instead of Foo holding an instance of a DOM element, it holds and instance of Bar that gets adapted into an instance of a DOM element.
Foo
import javax.xml.bind.annotation.*;
import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
#XmlRootElement
public class Foo {
private Bar bar;
#XmlAnyElement
#XmlJavaTypeAdapter(BarAdapter.class)
public Bar getBar() {
return bar;
}
public void setBar(Bar bar) {
this.bar = bar;
}
}
Bar
public class Bar {
private String value;
public String getValue() {
return value;
}
public void setValue(String value) {
this.value = value;
}
}
BarAdapter
import javax.xml.bind.annotation.adapters.XmlAdapter;
import javax.xml.parsers.*;
import org.w3c.dom.*;
public class BarAdapter extends XmlAdapter<Object, Bar>{
#Override
public Object marshal(Bar bar) throws Exception {
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = dbf.newDocumentBuilder();
Document document = db.newDocument();
Element element = document.createElementNS("http://www.example.com/BAR", "ns:bar");
element.setTextContent(bar.getValue());
return element;
}
#Override
public Bar unmarshal(Object arg0) throws Exception {
// TODO Auto-generated method stub
return null;
}
}
Grab Namespace Declarations
Since your object model does not hold the DOM elements directly you can't traverse it to get the namespace declarations. Instead we could do a marshal to a ContentHandler to collect them. Below are the reasons for marshalling to a ContentHandler:
It gives us an easy event which we can use to collection the namespace declarations.
It doesn't actually produce anything so it is the lightest marshal target we can use.
NsContentHandler contentHandler = new NsContentHandler();
marshaller.marshal(foo, contentHandler);
NsContentHandler
The implementation of ContentHandler will look something like:
import java.util.*;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
public class NsContentHandler extends DefaultHandler {
private Map<String, String> namespaces = new TreeMap<String, String>();
#Override
public void startPrefixMapping(String prefix, String uri) throws SAXException {
if(!namespaces.containsKey(prefix)) {
namespaces.put(prefix, uri);
}
}
public Map<String, String> getNamespaces() {
return namespaces;
}
}
Specify the Namespaces to Include on Root Element
The implementation of MyNamespacePrefixMapper changes a little to use the namrespaces captured from our ContentHandler.
import java.util.Map;
import java.util.Map.Entry;
import com.sun.xml.bind.marshaller.*;
public class MyNamespacePrefixMapper extends NamespacePrefixMapper {
private String[] namespaces;
public MyNamespacePrefixMapper(Map<String, String> namespaces) {
this.namespaces = new String[namespaces.size() * 2];
int index = 0;
for(Entry<String, String> entry : namespaces.entrySet()) {
this.namespaces[index++] = entry.getKey();
this.namespaces[index++] = entry.getValue();
}
}
#Override
public String getPreferredPrefix(String arg0, String arg1, boolean arg2) {
return null;
}
#Override
public String[] getPreDeclaredNamespaceUris2() {
return namespaces;
}
}
Demo Code
import javax.xml.bind.*;
public class Demo {
public static void main(String[] args) throws Exception {
JAXBContext jc = JAXBContext.newInstance(Foo.class);
Bar bar = new Bar();
bar.setValue("Hello World");
Foo foo = new Foo();
foo.setBar(bar);
Marshaller marshaller = jc.createMarshaller();
// Marshal First Time to Get Namespace Declarations
NsContentHandler contentHandler = new NsContentHandler();
marshaller.marshal(foo, contentHandler);
// Marshal Second Time for Real
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
marshaller.setProperty("com.sun.xml.bind.namespacePrefixMapper", new MyNamespacePrefixMapper(contentHandler.getNamespaces()));
marshaller.marshal(foo, System.out);
}
}
Output
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<foo xmlns:ns="http://www.example.com/BAR">
<ns:bar>Hello World</ns:bar>
</foo>
I use REST and i was wondering if i can tell jaxb to insert a string field "as-it-is" into the outgoing xml.
Certainly i count unpack it before returning, but i would like to save this step.
#XmlRootElement(name="unnestedResponse")
public class Response{
#Insert annotation here ;-)
private String alreadyXml;
private int otherDate; ...
}
Is there a possability to tell JAXB to just use the String as it is without escapting? I want that the client does not have to parse my response and then parse this field.
greetings,
m
You can use the #XmlAnyElement and specify a DomHandler to keep a portion of the XML document as a String.
Customer
import javax.xml.bind.annotation.*;
#XmlRootElement
public class Customer {
private String bio;
#XmlAnyElement(BioHandler.class)
public String getBio() {
return bio;
}
public void setBio(String bio) {
this.bio = bio;
}
}
BioHandler
import java.io.*;
import javax.xml.bind.ValidationEventHandler;
import javax.xml.bind.annotation.DomHandler;
import javax.xml.transform.Source;
import javax.xml.transform.stream.*;
public class BioHandler implements DomHandler<String, StreamResult> {
private static final String BIO_START_TAG = "<bio>";
private static final String BIO_END_TAG = "</bio>";
private StringWriter xmlWriter = new StringWriter();
public StreamResult createUnmarshaller(ValidationEventHandler errorHandler) {
return new StreamResult(xmlWriter);
}
public String getElement(StreamResult rt) {
String xml = rt.getWriter().toString();
int beginIndex = xml.indexOf(BIO_START_TAG) + BIO_START_TAG.length();
int endIndex = xml.indexOf(BIO_END_TAG);
return xml.substring(beginIndex, endIndex);
}
public Source marshal(String n, ValidationEventHandler errorHandler) {
try {
String xml = BIO_START_TAG + n.trim() + BIO_END_TAG;
StringReader xmlReader = new StringReader(xml);
return new StreamSource(xmlReader);
} catch(Exception e) {
throw new RuntimeException(e);
}
}
}
For More Information
http://blog.bdoughan.com/2011/04/xmlanyelement-and-non-dom-properties.html
Following bdoughan's answer did not work for me as I encountered errors during marshalling when the text contained the '& character (e.g. in URLs or when using HTML entities such as e.g. " ").
I was able to resolve this by changing the custom DomHandler's marshal method to
public Source marshal(String et, ValidationEventHandler veh) {
Node node = new SimpleTextNode(et);
return new DOMSource(node);
}
where SimpleTextNode implements the Node interface as follows:
class SimpleTextNode implements Node {
String nodeValue = "";
#Override
public SimpleTextNode(String nodeValue) {
this.nodeValue = nodeValue;
}
#Override
public short getNodeType() {
return TEXT_NODE;
}
// the remaining methods of the Node interface are not needed during marshalling
// you can just use the code template of your IDE...
...
}
PS: I would have loved to leave this as a comment to bdoughan's answer, but unfortunately I have way too little reputation :-(
Ok, so we all know that Maps are somewhat of a pain in JAXB.
I here present an alternative to the current solutions. My main objective is to get feedback on any and all potential problems with this solution. Maybe it is not even a good solution for some reasons.
When I played around with the standard Generic Map Adapter it seemed like the adapters for the classes were not used. The classes are instead scanned, forcing me to mark my data model with JAXB annotations and adding default constructors where I don't want them (I'm talking about complex classes that I want to store in Maps, not simple data types). Above all, this makes my internal data model public thereby breaking encapsulation since the generated XML is a direct representation of the internal structures.
The "workaround" I did was to combine the adapter with the Marshall.Listener and Unmarshall.Listner thereby being able to extract additional annotation information. A field would then be
#XmlElement(name = "testMap")
#XmlJavaTypeAdapter(MapAdapter.class)
#MapKeyValueAdapters(key=SomeComplexClassAdapter.class)
private final HashMap<SomeComplexClass, String> testMap2 = new HashMap<SomeComplexClass, String>();
This additional annotation accepts both key and value as arguments. If omitted the functionality falls back on standard qualification for the omitted. The example above will use the given adapter for the key and standard handling for the value.
Here the annotation.
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
import javax.xml.bind.annotation.adapters.XmlAdapter;
/**
* This annotation holds the adapters for the key and value used in the MapAdapter.
*/
#Retention(RUNTIME)
#Target({ FIELD })
public #interface MapKeyValueAdapters {
/**
* Points to the class that converts the value type to a bound type or vice versa. See {#link XmlAdapter} for more
* details.
*/
Class<? extends XmlAdapter<?, ?>> key() default UNDEFINED.class;
/**
* Points to the class that converts the value type to a bound type or vice versa. See {#link XmlAdapter} for more
* details.
*/
Class<? extends XmlAdapter<?, ?>> value() default UNDEFINED.class;
static final class UNDEFINED extends XmlAdapter<String, String> {
#Override
public String unmarshal(String v) throws Exception {
return null;
}
#Override
public String marshal(String v) throws Exception {
return null;
}
}
}
Here so the adapter
import java.io.StringReader;
import java.io.StringWriter;
import java.lang.annotation.Annotation;
import java.lang.annotation.IncompleteAnnotationException;
import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBElement;
import javax.xml.bind.JAXBIntrospector;
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.XmlType;
import javax.xml.bind.annotation.adapters.XmlAdapter;
import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
import javax.xml.namespace.QName;
/**
* This class represents a general purpose Map adapter. It is capable of handling any type of class implementing the Map
* interface and has a no-args constructor.
*/
public class MapAdapter extends XmlAdapter<MapAdapter.Wrapper, Map<Object, Object>> {
private static final String XSI_NS = "xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\"";
private static final String XSI_TYPE = "xsi:type";
private static final String CDATA_START = "<![CDATA[";
private static final String CDATA_END = "]]>";
private final MarshallerListener marshallerListener = new MarshallerListener();
private final UnmarshallerListener unmarshallerListener = new UnmarshallerListener();
private final JAXBContext context;
public MapAdapter(JAXBContext inContext) {
context = inContext;
}
#SuppressWarnings({ "unchecked", "rawtypes" })
#Override
public Map<Object, Object> unmarshal(Wrapper inWrapper) throws Exception {
if (inWrapper == null) {
return null;
}
Info info = null;
for (Info element : unmarshallerListener.infoList) {
if (element.field.equals(inWrapper.field)) {
info = element;
}
}
if (info != null) {
Class<Map<Object, Object>> clazz = (Class<Map<Object, Object>>) Class.forName(inWrapper.mapClass);
Map<Object, Object> outMap = clazz.newInstance();
XmlAdapter<Object, Object> keyAdapter = null;
XmlAdapter<Object, Object> valueAdapter = null;
if (info.adapters.key() != MapKeyValueAdapters.UNDEFINED.class) {
keyAdapter = (XmlAdapter<Object, Object>) info.adapters.key().getConstructor().newInstance();
}
if (info.adapters.value() != MapKeyValueAdapters.UNDEFINED.class) {
valueAdapter = (XmlAdapter<Object, Object>) info.adapters.value().getConstructor().newInstance();
}
Unmarshaller um = context.createUnmarshaller();
for (MapEntry entry : inWrapper.mapList) {
Object key = ((JAXBElement) um.unmarshal(new StringReader(entry.key))).getValue();
if (keyAdapter != null) {
key = keyAdapter.unmarshal(key);
}
Object value = ((JAXBElement) um.unmarshal(new StringReader(entry.value))).getValue();
if (valueAdapter != null) {
value = valueAdapter.unmarshal(value);
}
outMap.put(key, value);
}
return outMap;
} else {
throw new IllegalStateException("Adapter info could not be found.");
}
}
#SuppressWarnings("unchecked")
#Override
public Wrapper marshal(Map<Object, Object> inMap) throws Exception {
if (inMap == null) {
return null;
}
Info info = null;
for (Info element : marshallerListener.infoList) {
if (element.map == inMap) {
info = element;
}
}
if (info != null) {
Wrapper outWrapper = new Wrapper();
outWrapper.mapClass = inMap.getClass().getName();
outWrapper.field = info.field;
Marshaller m = context.createMarshaller();
m.setProperty(Marshaller.JAXB_FRAGMENT, true);
JAXBIntrospector introspector = context.createJAXBIntrospector();
XmlAdapter<Object, Object> keyAdapter = null;
XmlAdapter<Object, Object> valueAdapter = null;
if (info.adapters.key() != MapKeyValueAdapters.UNDEFINED.class) {
keyAdapter = (XmlAdapter<Object, Object>) info.adapters.key().getConstructor().newInstance();
}
if (info.adapters.value() != MapKeyValueAdapters.UNDEFINED.class) {
valueAdapter = (XmlAdapter<Object, Object>) info.adapters.value().getConstructor().newInstance();
}
for (Map.Entry<?, ?> entry : inMap.entrySet()) {
MapEntry jaxbEntry = new MapEntry();
outWrapper.mapList.add(jaxbEntry);
Object key = entry.getKey();
if (key != null) {
Class<Object> clazz = Object.class;
if (keyAdapter != null) {
key = keyAdapter.marshal(key);
clazz = (Class<Object>) key.getClass();
}
if (introspector.getElementName(key) == null) {
// The value of clazz determines if the qualification is written or not; Object.class generates the
// qualification.
key = new JAXBElement<Object>(new QName("key"), clazz, key);
}
StringWriter writer = new StringWriter();
m.marshal(key, writer);
jaxbEntry.key = format("key", writer.toString());
}
Object value = entry.getValue();
if (value != null) {
Class<Object> clazz = Object.class;
if (valueAdapter != null) {
value = valueAdapter.marshal(value);
clazz = (Class<Object>) value.getClass();
}
if (introspector.getElementName(value) == null) {
// The value of clazz determines if the qualification is written or not; Object.class generates the
// qualification.
value = new JAXBElement<Object>(new QName("value"), clazz, value);
}
StringWriter writer = new StringWriter();
m.marshal(value, writer);
jaxbEntry.value = format("value", writer.toString());
}
}
return outWrapper;
} else {
throw new IllegalStateException("Adapter info could not be found.");
}
}
private String format(String inTagName, String inXML) {
String element = "<" + inTagName;
// Remove unneeded namespaces, they are already declared in the top node.
int beginIndex = inXML.indexOf(XSI_TYPE);
if (beginIndex != -1) {
int endIndex = inXML.indexOf(" ", beginIndex);
element += " " + inXML.substring(beginIndex, endIndex) + " " + XSI_NS;
}
beginIndex = inXML.indexOf('>');
element += inXML.substring(beginIndex);
return CDATA_START + element + CDATA_END;
}
#XmlType(name = "map")
static class Wrapper {
#XmlElement(name = "mapClass")
private String mapClass;
#XmlElement(name = "field")
private String field;
#XmlElementWrapper(name = "map")
#XmlElement(name = "entry")
private final List<MapEntry> mapList = new ArrayList<MapEntry>();
}
#XmlType(name = "mapEntry")
static class MapEntry {
#XmlElement(name = "key")
private String key;
#XmlElement(name = "value")
private String value;
}
public Marshaller.Listener getMarshallerListener() {
return marshallerListener;
}
public Unmarshaller.Listener getUnmarshallerListener() {
return unmarshallerListener;
}
private static class MarshallerListener extends Marshaller.Listener {
private final List<Info> infoList = new ArrayList<Info>();
#Override
public void beforeMarshal(Object inSource) {
extractInfo(infoList, inSource);
}
}
private class UnmarshallerListener extends Unmarshaller.Listener {
private final List<Info> infoList = new ArrayList<Info>();
#Override
public void beforeUnmarshal(Object inTarget, Object inParent) {
extractInfo(infoList, inTarget);
}
}
private static void extractInfo(List<Info> inList, Object inObject) {
for (Field field : inObject.getClass().getDeclaredFields()) {
for (Annotation a : field.getAnnotations()) {
if (a.annotationType() == XmlJavaTypeAdapter.class) {
if (((XmlJavaTypeAdapter) a).value() == MapAdapter.class) {
MapKeyValueAdapters adapters = field.getAnnotation(MapKeyValueAdapters.class);
if (adapters == null) {
throw new IncompleteAnnotationException(XmlJavaTypeAdapter.class, "; XmlJavaTypeAdapter specifies "
+ MapAdapter.class.getName() + " for field " + field.getName() + " in "
+ inObject.getClass().getName() + ". This must be used in combination with annotation "
+ MapKeyValueAdapters.class.getName());
}
try {
field.setAccessible(true);
Map<?, ?> value = (Map<?, ?>) field.get(inObject);
if (value != null) {
Info info = new Info();
info.field = field.getName();
info.map = value;
info.adapters = adapters;
inList.add(info);
}
} catch (Exception e) {
throw new RuntimeException("Failed extracting annotation information from " + field.getName() + " in "
+ inObject.getClass().getName(), e);
}
}
}
}
}
}
private static class Info {
private String field;
private Map<?, ?> map;
private MapKeyValueAdapters adapters;
}
}
Note that the adapter is capable of handling all types of Maps as long as it has a default constructor.
Finally the code to set up the usage of the adapter.
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;
/**
* Singleton that manages the JAXB functionality.
*/
public enum JAXBManager {
INSTANCE;
private JAXBContext context;
private JAXBManager() {
try {
context = JAXBContext.newInstance(SomeComplexClass.class.getPackage().getName());
} catch (JAXBException e) {
throw new RuntimeException(e);
}
}
public Marshaller createMarshaller() throws JAXBException {
Marshaller m = context.createMarshaller();
MapAdapter adapter = new MapAdapter(context);
m.setAdapter(adapter);
m.setListener(adapter.getMarshallerListener());
m.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
return m;
}
public Unmarshaller createUnmarshaller() throws JAXBException {
Unmarshaller um = context.createUnmarshaller();
MapAdapter adapter = new MapAdapter(context);
um.setAdapter(adapter);
um.setListener(adapter.getUnmarshallerListener());
return um;
}
}
This could generate an output of something like
<testMap2>
<mapClass>java.util.HashMap</mapClass>
<field>testMap2</field>
<map>
<entry>
<key><![CDATA[<key><number>1357</number><type>Unspecified</type></key>]]></key>
<value><![CDATA[<value xsi:type="xs:string" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">gn</value>]]></value>
</entry>
</map>
</testMap2>
As can be seen the qualification info is not needed for the key since we already know the adapter to use.
Also note that I add CDATA to the output. I have implemented a simple character escape handler that respects this (not included in this code example).
Due to our release cycles I have a bit of time before the opportunity opens for implementing this functionality in our code so I therefore thought it would be wise to check with the community if there are any problems with this solution or if there are better ways already in the JAXB specification that I have overlooked. I also assume that there are sections of the code that can be done in better ways.
Thanks for comments.
Here is my proposal for a workaround:
Make the map XmlTransient
Use a wrapped List for the marshalling
reinit the map from the list whenever it is needed
if you need to keep the list and the map in sync use an add(order) function
Example Customer with a Map of Orders
#XmlRootElement
#XmlAccessorType(XmlAccessType.FIELD)
public static class Order {
#XmlID
String orderId;
String item;
int count;
}
#XmlRootElement(name = "customer")
#XmlAccessorType(XmlAccessType.FIELD)
public static class Customer {
String name;
String firstname;
#XmlElementWrapper(name = "orders")
#XmlElement(name = "order")
List<Order> orders = new ArrayList<Order>();
#XmlTransient
private Map<String, Order> ordermap = new LinkedHashMap<String, Order>();
/**
* reinitialize the order list
*/
public void reinit() {
for (Order order : orders) {
ordermap.put(order.orderId, order);
}
}
/**
* add the given order to the internal list and map
* #param order - the order to add
*/
public void addOrder(Order order) {
orders.add(order);
ordermap.put(order.orderId,order);
}
}
Example XML
<customer>
<name>Doe</name>
<firstname>John</firstname>
<orders>
<order>
<orderId>Id1</orderId>
<item>Item 1</item>
<count>1</count>
</order>
<order>
<orderId>Id2</orderId>
<item>Item 2</item>
<count>2</count>
</order>
</orders>
</customer>
Mininimal complete and verifiable example
An example according to
https://stackoverflow.com/help/mcve
can be found at
https://github.com/BITPlan/com.bitplan.simplerest/blob/master/src/test/java/com/bitplan/jaxb/TestJaxbFactory.java#L390
In my XML I have
<myelem required="false"/>
How I can read the required attribute as a boolean? I can read it as String and inside a getter do this: return new Boolean(required)
But maybe there are some more elegant ways?
Just simply use boolean for the member in your Java class:
#XmlAttribute
private boolean required;
Or, if you use getter-setter style of mapping:
#XmlAttribute
public boolean isRequired() {
return required;
}
The JAXB unmarshaller is able to interpret "true" and "false" strings in the XML document as boolean value.
UPDATE:
I tested this with the following classes:
test/MyElem.java:
package test;
import javax.xml.bind.annotation.*;
#XmlRootElement(name="myelem")
public class MyElem {
private boolean required;
#XmlAttribute
public boolean isRequired() {
return required;
}
public void setRequired(boolean value) {
required = value;
}
}
Test.java:
import javax.xml.bind.*;
import java.io.*;
import test.*;
public class Test {
public static void main(String[] args) {
try {
JAXBContext jc = JAXBContext.newInstance(MyElem.class);
Unmarshaller u = jc.createUnmarshaller();
Object o = u.unmarshal( new File( "test.xml" ) );
System.out.println(((MyElem)o).isRequired());
} catch(Exception e) {
e.printStackTrace();
}
}
}
And with the following input (test.xml):
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<myelem required="true"/>
I get the correct result on the console:
true