/*
* Copyright 2002-2017 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.http.codec.xml;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.function.Function;
import javax.xml.XMLConstants;
import javax.xml.bind.JAXBElement;
import javax.xml.bind.JAXBException;
import javax.xml.bind.UnmarshalException;
import javax.xml.bind.Unmarshaller;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlSchema;
import javax.xml.bind.annotation.XmlType;
import javax.xml.namespace.QName;
import javax.xml.stream.XMLEventReader;
import javax.xml.stream.events.XMLEvent;
import org.reactivestreams.Publisher;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;
import org.springframework.core.ResolvableType;
import org.springframework.core.codec.AbstractDecoder;
import org.springframework.core.codec.CodecException;
import org.springframework.core.codec.DecodingException;
import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.util.ClassUtils;
import org.springframework.util.MimeType;
import org.springframework.util.MimeTypeUtils;
import org.springframework.util.xml.StaxUtils;
/**
* Decode from a bytes stream containing XML elements to a stream of
* {@code Object}s (POJOs).
*
* @author Sebastien Deleuze
* @author Arjen Poutsma
* @since 5.0
* @see Jaxb2XmlEncoder
*/
public class Jaxb2XmlDecoder extends AbstractDecoder<Object> {
/**
* The default value for JAXB annotations.
* @see XmlRootElement#name()
* @see XmlRootElement#namespace()
* @see XmlType#name()
* @see XmlType#namespace()
*/
private static final String JAXB_DEFAULT_ANNOTATION_VALUE = "##default";
private final XmlEventDecoder xmlEventDecoder = new XmlEventDecoder();
private final JaxbContextContainer jaxbContexts = new JaxbContextContainer();
public Jaxb2XmlDecoder() {
super(MimeTypeUtils.APPLICATION_XML, MimeTypeUtils.TEXT_XML);
}
@Override
public boolean canDecode(ResolvableType elementType, MimeType mimeType) {
if (super.canDecode(elementType, mimeType)) {
Class<?> outputClass = elementType.getRawClass();
return outputClass.isAnnotationPresent(XmlRootElement.class) ||
outputClass.isAnnotationPresent(XmlType.class);
}
else {
return false;
}
}
@Override
public Flux<Object> decode(Publisher<DataBuffer> inputStream, ResolvableType elementType,
MimeType mimeType, Map<String, Object> hints) {
Class<?> outputClass = elementType.getRawClass();
Flux<XMLEvent> xmlEventFlux = this.xmlEventDecoder.decode(inputStream, null, mimeType, hints);
QName typeName = toQName(outputClass);
Flux<List<XMLEvent>> splitEvents = split(xmlEventFlux, typeName);
return splitEvents.map(events -> unmarshal(events, outputClass));
}
private Object unmarshal(List<XMLEvent> events, Class<?> outputClass) {
try {
Unmarshaller unmarshaller = this.jaxbContexts.createUnmarshaller(outputClass);
XMLEventReader eventReader = StaxUtils.createXMLEventReader(events);
if (outputClass.isAnnotationPresent(XmlRootElement.class)) {
return unmarshaller.unmarshal(eventReader);
}
else {
JAXBElement<?> jaxbElement = unmarshaller.unmarshal(eventReader, outputClass);
return jaxbElement.getValue();
}
}
catch (UnmarshalException ex) {
throw new DecodingException("Could not unmarshal XML to " + outputClass, ex);
}
catch (JAXBException ex) {
throw new CodecException("Invalid JAXB configuration", ex);
}
}
/**
* Returns the qualified name for the given class, according to the mapping rules
* in the JAXB specification.
*/
QName toQName(Class<?> outputClass) {
String localPart;
String namespaceUri;
if (outputClass.isAnnotationPresent(XmlRootElement.class)) {
XmlRootElement annotation = outputClass.getAnnotation(XmlRootElement.class);
localPart = annotation.name();
namespaceUri = annotation.namespace();
}
else if (outputClass.isAnnotationPresent(XmlType.class)) {
XmlType annotation = outputClass.getAnnotation(XmlType.class);
localPart = annotation.name();
namespaceUri = annotation.namespace();
}
else {
throw new IllegalArgumentException("Output class [" + outputClass.getName() +
"] is neither annotated with @XmlRootElement nor @XmlType");
}
if (JAXB_DEFAULT_ANNOTATION_VALUE.equals(localPart)) {
localPart = ClassUtils.getShortNameAsProperty(outputClass);
}
if (JAXB_DEFAULT_ANNOTATION_VALUE.equals(namespaceUri)) {
Package outputClassPackage = outputClass.getPackage();
if (outputClassPackage != null && outputClassPackage.isAnnotationPresent(XmlSchema.class)) {
XmlSchema annotation = outputClassPackage.getAnnotation(XmlSchema.class);
namespaceUri = annotation.namespace();
}
else {
namespaceUri = XMLConstants.NULL_NS_URI;
}
}
return new QName(namespaceUri, localPart);
}
/**
* Split a flux of {@link XMLEvent}s into a flux of XMLEvent lists, one list
* for each branch of the tree that starts with the given qualified name.
* That is, given the XMLEvents shown {@linkplain XmlEventDecoder here},
* and the {@code desiredName} "{@code child}", this method returns a flux
* of two lists, each of which containing the events of a particular branch
* of the tree that starts with "{@code child}".
* <ol>
* <li>The first list, dealing with the first branch of the tree:
* <ol>
* <li>{@link javax.xml.stream.events.StartElement} {@code child}</li>
* <li>{@link javax.xml.stream.events.Characters} {@code foo}</li>
* <li>{@link javax.xml.stream.events.EndElement} {@code child}</li>
* </ol>
* <li>The second list, dealing with the second branch of the tree:
* <ol>
* <li>{@link javax.xml.stream.events.StartElement} {@code child}</li>
* <li>{@link javax.xml.stream.events.Characters} {@code bar}</li>
* <li>{@link javax.xml.stream.events.EndElement} {@code child}</li>
* </ol>
* </li>
* </ol>
*/
Flux<List<XMLEvent>> split(Flux<XMLEvent> xmlEventFlux, QName desiredName) {
return xmlEventFlux.flatMap(new SplitFunction(desiredName));
}
private static class SplitFunction implements Function<XMLEvent, Publisher<? extends List<XMLEvent>>> {
private final QName desiredName;
private List<XMLEvent> events;
private int elementDepth = 0;
private int barrier = Integer.MAX_VALUE;
public SplitFunction(QName desiredName) {
this.desiredName = desiredName;
}
@Override
public Publisher<? extends List<XMLEvent>> apply(XMLEvent event) {
if (event.isStartElement()) {
if (this.barrier == Integer.MAX_VALUE) {
QName startElementName = event.asStartElement().getName();
if (this.desiredName.equals(startElementName)) {
this.events = new ArrayList<>();
this.barrier = this.elementDepth;
}
}
this.elementDepth++;
}
if (this.elementDepth > this.barrier) {
this.events.add(event);
}
if (event.isEndElement()) {
this.elementDepth--;
if (this.elementDepth == this.barrier) {
this.barrier = Integer.MAX_VALUE;
return Mono.just(this.events);
}
}
return Mono.empty();
}
}
}