org.apache.axiom.om.util.ElementHelper Maven / Gradle / Ivy
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* to you under the Apache License, Version 2.0 (the
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* http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.axiom.om.util;
import org.apache.axiom.om.OMAttribute;
import org.apache.axiom.om.OMElement;
import org.apache.axiom.om.OMException;
import org.apache.axiom.om.OMFactory;
import org.apache.axiom.om.OMNamespace;
import org.apache.axiom.om.OMNode;
import org.apache.axiom.om.OMSourcedElement;
import org.apache.axiom.om.OMText;
import org.apache.axiom.om.ds.ByteArrayDataSource;
import org.apache.axiom.om.impl.builder.StAXOMBuilder;
import org.apache.axiom.soap.SOAPFactory;
import org.apache.axiom.soap.SOAPHeaderBlock;
import org.apache.axiom.util.stax.XMLStreamReaderUtils;
import org.apache.axiom.util.stax.xop.XOPUtils;
import javax.xml.namespace.QName;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;
import java.io.Writer;
import java.util.Iterator;
/**
* Helper class to provide extra utility stuff against elements. The code is designed to work with
* any element implementation.
*/
public class ElementHelper {
private OMElement element;
/**
* Constructs and binds to an element.
*
* @param element element to work with
*/
public ElementHelper(OMElement element) {
this.element = element;
}
/**
* Turns a prefix:local qname string into a proper QName, evaluating it in the OMElement
* context.
*
* @param qname qname to resolve
* @param defaultToParentNameSpace flag that controls behaviour when there is no namespace.
* @return Returns null for any failure to extract a qname.
*/
public QName resolveQName(String qname, boolean defaultToParentNameSpace) {
int colon = qname.indexOf(':');
if (colon < 0) {
if (defaultToParentNameSpace) {
//get the parent ns and use it for the child
OMNamespace namespace = element.getNamespace();
if (namespace != null) {
// Guard against QName implementation sillyness.
if (namespace.getPrefix() == null)
return new QName(namespace.getNamespaceURI(), qname);
else
return new QName(namespace.getNamespaceURI(), qname, namespace.getPrefix());
}
}
//else things without no prefix are local.
return new QName(qname);
}
String prefix = qname.substring(0, colon);
String local = qname.substring(colon + 1);
if (local.length() == 0) {
//empy local, exit accordingly
return null;
}
OMNamespace namespace = element.findNamespaceURI(prefix);
if (namespace == null) {
return null;
}
return new QName(namespace.getNamespaceURI(), local, prefix);
}
/**
* Turns a prefix:local qname string into a proper QName, evaluating it in the OMElement
* context. Unprefixed qnames resolve to the local namespace.
*
* @param qname prefixed qname string to resolve
* @return Returns null for any failure to extract a qname.
*/
public QName resolveQName(String qname) {
return resolveQName(qname, true);
}
public static void setNewElement(OMElement parent,
OMElement myElement,
OMElement newElement) {
if (myElement != null) {
myElement.discard();
}
parent.addChild(newElement);
}
/**
* @deprecated please use OMElement.getFirstChildWithName(qname) instead!
*/
public static OMElement getChildWithName(OMElement parent,
String childName) {
Iterator childrenIter = parent.getChildren();
while (childrenIter.hasNext()) {
OMNode node = (OMNode) childrenIter.next();
if (node.getType() == OMNode.ELEMENT_NODE &&
childName.equals(((OMElement) node).getLocalName())) {
return (OMElement) node;
}
}
return null;
}
/**
* @deprecated use {@link #getContentID(XMLStreamReader)} instead (see WSCOMMONS-429)
*/
public static String getContentID(XMLStreamReader parser, String charsetEncoding) {
return getContentID(parser);
}
public static String getContentID(XMLStreamReader parser) {
if (parser.getAttributeCount() > 0 &&
parser.getAttributeLocalName(0).equals("href")) {
return getContentIDFromHref(parser.getAttributeValue(0));
} else {
throw new OMException(
"Href attribute not found in XOP:Include element");
}
}
/**
* Extract the content ID from a href attribute value, i.e. from a URI following the
* cid: scheme defined by RFC2392.
*
* @param href the value of the href attribute
* @return the corresponding content ID
*/
public static String getContentIDFromHref(String href) {
return XOPUtils.getContentIDFromURL(href);
}
/**
* Some times two OMElements needs to be added to the same object tree. But in Axiom, a single
* tree should always contain object created from the same type of factory (eg:
* LinkedListImplFactory, DOMFactory, etc.,). If one OMElement is created from a different
* factory than that of the factory which was used to create the object in the existing tree, we
* need to convert the new OMElement to match to the factory of existing object tree. This
* method will convert omElement to the given omFactory.
*
* @see AttributeHelper#importOMAttribute(OMAttribute, OMElement) to convert instances of
* OMAttribute
*/
public static OMElement importOMElement(OMElement omElement, OMFactory omFactory) {
// first check whether the given OMElement has the same omFactory
if (omElement.getOMFactory().getClass().isInstance(omFactory)) {
return omElement;
} else {
OMElement documentElement = new StAXOMBuilder(omFactory, omElement.getXMLStreamReader())
.getDocumentElement();
documentElement.build();
return documentElement;
}
}
/**
* This is a method to convert regular OMElements to SOAPHeaderBlocks.
*
* @param omElement
* @param factory
* @return TODO
* @throws Exception
*/
public static SOAPHeaderBlock toSOAPHeaderBlock(OMElement omElement, SOAPFactory factory) throws Exception {
if (omElement instanceof SOAPHeaderBlock)
return (SOAPHeaderBlock) omElement;
QName name = omElement.getQName();
String localName = name.getLocalPart();
OMNamespace namespace = factory.createOMNamespace(name.getNamespaceURI(), name.getPrefix());
ByteArrayOutputStream baos = new ByteArrayOutputStream();
omElement.serialize(baos);
ByteArrayDataSource bads = new ByteArrayDataSource(baos.toByteArray(), "utf-8");
SOAPHeaderBlock block = factory.createSOAPHeaderBlock(localName, namespace, bads);
return block;
}
/**
* Returns a stream representing the concatenation of the text nodes that are children of a
* given element.
* The stream returned by this method produces exactly the same character sequence as the
* the stream created by the following expression:
* new StringReader(element.getText())
* The difference is that the stream implementation returned by this method is guaranteed
* to have constant memory usage and is optimized for performance.
*
* @param element the element to read the text nodes from
* @param cache whether to enable caching when accessing the element
* @return a stream representing the concatenation of the text nodes
*
* @see OMElement#getText()
*/
public static Reader getTextAsStream(OMElement element, boolean cache) {
// If the element is not an OMSourcedElement and has not more than one child, then the most
// efficient way to get the Reader is to build a StringReader
if (!(element instanceof OMSourcedElement) && (!cache || element.isComplete())) {
OMNode child = element.getFirstOMChild();
if (child == null) {
return new StringReader("");
} else if (child.getNextOMSibling() == null) {
return new StringReader(child instanceof OMText ? ((OMText)child).getText() : "");
}
}
// In all other cases, extract the data from the XMLStreamReader
try {
XMLStreamReader reader = element.getXMLStreamReader(cache);
if (reader.getEventType() == XMLStreamReader.START_DOCUMENT) {
reader.next();
}
return XMLStreamReaderUtils.getElementTextAsStream(reader, true);
} catch (XMLStreamException ex) {
throw new OMException(ex);
}
}
/**
* Write the content of the text nodes that are children of a given element to a
* {@link Writer}.
* If cache is true, this method has the same effect as the following instruction:
* out.write(element.getText())
* The difference is that this method is guaranteed to have constant memory usage and is
* optimized for performance.
*
* @param element the element to read the text nodes from
* @param out the stream to write the content to
* @param cache whether to enable caching when accessing the element
* @throws XMLStreamException if an error occurs when reading from the element
* @throws IOException if an error occurs when writing to the stream
*
* @see OMElement#getText()
*/
public static void writeTextTo(OMElement element, Writer out, boolean cache)
throws XMLStreamException, IOException {
XMLStreamReader reader = cache ? element.getXMLStreamReader()
: element.getXMLStreamReaderWithoutCaching();
int depth = 0;
while (reader.hasNext()) {
switch (reader.next()) {
case XMLStreamReader.CHARACTERS:
case XMLStreamReader.CDATA:
if (depth == 1) {
out.write(reader.getText());
}
break;
case XMLStreamReader.START_ELEMENT:
depth++;
break;
case XMLStreamReader.END_ELEMENT:
depth--;
}
}
}
}
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