W3CDom.java
package org.jsoup.helper;
import org.jsoup.internal.NamespaceBindings;
import org.jsoup.internal.StringUtil;
import org.jsoup.nodes.Attribute;
import org.jsoup.nodes.Attributes;
import org.jsoup.nodes.CDataNode;
import org.jsoup.nodes.Comment;
import org.jsoup.nodes.DataNode;
import org.jsoup.nodes.TextNode;
import org.jsoup.nodes.XmlDeclaration;
import org.jsoup.parser.Parser;
import org.jsoup.select.NodeVisitor;
import org.jsoup.select.Selector;
import org.w3c.dom.DOMException;
import org.w3c.dom.Document;
import org.w3c.dom.DocumentType;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.jspecify.annotations.Nullable;
import javax.xml.XMLConstants;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;
import javax.xml.xpath.XPathFactoryConfigurationException;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import static javax.xml.transform.OutputKeys.METHOD;
import static org.jsoup.nodes.Document.OutputSettings.Syntax;
/**
* Helper class to transform a {@link org.jsoup.nodes.Document} to a {@link org.w3c.dom.Document org.w3c.dom.Document},
* for integration with toolsets that use the W3C DOM.
*/
public class W3CDom {
/** For W3C Documents created by this class, this property is set on each node to link back to the original jsoup node. */
public static final String SourceProperty = "jsoupSource";
private static final String ContextProperty = "jsoupContextSource"; // tracks the jsoup context element on w3c doc
private static final String ContextNodeProperty = "jsoupContextNode"; // the w3c node used as the creating context
/**
To get support for XPath versions > 1, set this property to the classname of an alternate XPathFactory
implementation. (For e.g. {@code net.sf.saxon.xpath.XPathFactoryImpl}).
*/
public static final String XPathFactoryProperty = "javax.xml.xpath.XPathFactory:jsoup";
protected DocumentBuilderFactory factory;
private boolean namespaceAware = true; // false when using selectXpath, for user's query convenience
public W3CDom() {
factory = DocumentBuilderFactory.newInstance();
factory.setNamespaceAware(true);
}
/**
Returns if this W3C DOM is namespace aware. By default, this will be {@code true}, but is disabled for simplicity
when using XPath selectors in {@link org.jsoup.nodes.Element#selectXpath(String)}.
@return the current namespace aware setting.
*/
public boolean namespaceAware() {
return namespaceAware;
}
/**
Update the namespace aware setting. This impacts the factory that is used to create W3C nodes from jsoup nodes.
<p>For HTML documents, controls if the document will be in the default {@code http://www.w3.org/1999/xhtml}
namespace if otherwise unset.</p>.
@param namespaceAware the updated setting
@return this W3CDom, for chaining.
*/
public W3CDom namespaceAware(boolean namespaceAware) {
this.namespaceAware = namespaceAware;
factory.setNamespaceAware(namespaceAware);
return this;
}
/**
* Converts a jsoup DOM to a W3C DOM.
*
* @param in jsoup Document
* @return W3C Document
*/
public static Document convert(org.jsoup.nodes.Document in) {
return (new W3CDom().fromJsoup(in));
}
/**
* Serialize a W3C document to a String. Provide Properties to define output settings including if HTML or XML. If
* you don't provide the properties ({@code null}), the output will be auto-detected based on the content of the
* document.
*
* @param doc Document
* @param properties (optional/nullable) the output properties to use. See {@link
* Transformer#setOutputProperties(Properties)} and {@link OutputKeys}
* @return Document as string
* @see #OutputHtml
* @see #OutputXml
* @see OutputKeys#ENCODING
* @see OutputKeys#OMIT_XML_DECLARATION
* @see OutputKeys#STANDALONE
* @see OutputKeys#DOCTYPE_PUBLIC
* @see OutputKeys#CDATA_SECTION_ELEMENTS
* @see OutputKeys#INDENT
* @see OutputKeys#MEDIA_TYPE
*/
public static String asString(Document doc, @Nullable Map<String, String> properties) {
try {
DOMSource domSource = new DOMSource(doc);
StringWriter writer = new StringWriter();
StreamResult result = new StreamResult(writer);
TransformerFactory tf = TransformerFactory.newInstance();
Transformer transformer = tf.newTransformer();
if (properties != null)
transformer.setOutputProperties(propertiesFromMap(properties));
if (doc.getDoctype() != null) {
DocumentType doctype = doc.getDoctype();
if (!StringUtil.isBlank(doctype.getPublicId()))
transformer.setOutputProperty(OutputKeys.DOCTYPE_PUBLIC, doctype.getPublicId());
if (!StringUtil.isBlank(doctype.getSystemId()))
transformer.setOutputProperty(OutputKeys.DOCTYPE_SYSTEM, doctype.getSystemId());
// handle <!doctype html> for legacy dom.
else if (doctype.getName().equalsIgnoreCase("html")
&& StringUtil.isBlank(doctype.getPublicId())
&& StringUtil.isBlank(doctype.getSystemId()))
transformer.setOutputProperty(OutputKeys.DOCTYPE_SYSTEM, "about:legacy-compat");
}
transformer.transform(domSource, result);
return writer.toString();
} catch (TransformerException e) {
throw new IllegalStateException(e);
}
}
static Properties propertiesFromMap(Map<String, String> map) {
Properties props = new Properties();
props.putAll(map);
return props;
}
/** Canned default for HTML output. */
public static HashMap<String, String> OutputHtml() {
return methodMap("html");
}
/** Canned default for XML output. */
public static HashMap<String, String> OutputXml() {
return methodMap("xml");
}
private static HashMap<String, String> methodMap(String method) {
HashMap<String, String> map = new HashMap<>();
map.put(METHOD, method);
return map;
}
/**
* Convert a jsoup Document to a W3C Document. The created nodes will link back to the original
* jsoup nodes in the user property {@link #SourceProperty} (but after conversion, changes on one side will not
* flow to the other).
*
* @param in jsoup doc
* @return a W3C DOM Document representing the jsoup Document or Element contents.
*/
public Document fromJsoup(org.jsoup.nodes.Document in) {
// just method API backcompat
return fromJsoup((org.jsoup.nodes.Element) in);
}
/**
* Convert a jsoup DOM to a W3C Document. The created nodes will link back to the original
* jsoup nodes in the user property {@link #SourceProperty} (but after conversion, changes on one side will not
* flow to the other). The input Element is used as a context node, but the whole surrounding jsoup Document is
* converted. (If you just want a subtree converted, use {@link #convert(org.jsoup.nodes.Element, Document)}.)
*
* @param in jsoup element or doc
* @return a W3C DOM Document representing the jsoup Document or Element contents.
* @see #sourceNodes(NodeList, Class)
* @see #contextNode(Document)
*/
public Document fromJsoup(org.jsoup.nodes.Element in) {
Validate.notNull(in);
DocumentBuilder builder;
try {
builder = factory.newDocumentBuilder();
Document out = builder.newDocument();
org.jsoup.nodes.Document inDoc = in.ownerDocument();
out.setXmlStandalone(true);
// if in is Document, use the root element, not the wrapping document, as the context:
org.jsoup.nodes.Element context = (in instanceof org.jsoup.nodes.Document) ? in.firstElementChild() : in;
out.setUserData(ContextProperty, context, null);
convert(inDoc != null ? inDoc : in, out);
return out;
} catch (ParserConfigurationException e) {
throw new IllegalStateException(e);
}
}
/**
* Converts a jsoup document into the provided W3C Document. If required, you can set options on the output
* document before converting.
*
* @param in jsoup doc
* @param out w3c doc
* @see org.jsoup.helper.W3CDom#fromJsoup(org.jsoup.nodes.Element)
*/
public void convert(org.jsoup.nodes.Document in, Document out) {
// just provides method API backcompat
convert((org.jsoup.nodes.Element) in, out);
}
/**
* Converts a jsoup element into the provided W3C Document. If required, you can set options on the output
* document before converting.
*
* @param in jsoup element
* @param out w3c doc
* @see org.jsoup.helper.W3CDom#fromJsoup(org.jsoup.nodes.Element)
*/
public void convert(org.jsoup.nodes.Element in, Document out) {
W3CBuilder builder = new W3CBuilder(out);
builder.namespaceAware = namespaceAware;
org.jsoup.nodes.Document inDoc = in.ownerDocument();
if (inDoc != null) {
if (!StringUtil.isBlank(inDoc.location())) {
out.setDocumentURI(inDoc.location());
}
builder.syntax = inDoc.outputSettings().syntax();
}
if (in instanceof org.jsoup.nodes.Document)
builder.traverseDocument((org.jsoup.nodes.Document) in);
else
builder.traverse(in);
}
/**
Evaluate an XPath query against the supplied document, and return the results.
@param xpath an XPath query
@param doc the document to evaluate against
@return the matches nodes
*/
public NodeList selectXpath(String xpath, Document doc) {
return selectXpath(xpath, (Node) doc);
}
/**
Evaluate an XPath query against the supplied context node, and return the results.
@param xpath an XPath query
@param contextNode the context node to evaluate against
@return the matches nodes
*/
public NodeList selectXpath(String xpath, Node contextNode) {
Validate.notEmptyParam(xpath, "xpath");
Validate.notNullParam(contextNode, "contextNode");
NodeList nodeList;
try {
// if there is a configured XPath factory, use that instead of the Java base impl:
String property = System.getProperty(XPathFactoryProperty);
final XPathFactory xPathFactory = property != null ?
XPathFactory.newInstance("jsoup") :
XPathFactory.newInstance();
XPathExpression expression = xPathFactory.newXPath().compile(xpath);
nodeList = (NodeList) expression.evaluate(contextNode, XPathConstants.NODESET); // love the strong typing here /s
Validate.notNull(nodeList);
} catch (XPathExpressionException | XPathFactoryConfigurationException e) {
throw new Selector.SelectorParseException(
e, "Could not evaluate XPath query [%s]: %s", xpath, e.getMessage());
}
return nodeList;
}
/**
Retrieves the original jsoup DOM nodes from a nodelist created by this convertor.
@param nodeList the W3C nodes to get the original jsoup nodes from
@param nodeType the jsoup node type to retrieve (e.g. Element, DataNode, etc)
@param <T> node type
@return a list of the original nodes
*/
public <T extends org.jsoup.nodes.Node> List<T> sourceNodes(NodeList nodeList, Class<T> nodeType) {
Validate.notNull(nodeList);
Validate.notNull(nodeType);
List<T> nodes = new ArrayList<>(nodeList.getLength());
for (int i = 0; i < nodeList.getLength(); i++) {
org.w3c.dom.Node node = nodeList.item(i);
Object source = node.getUserData(W3CDom.SourceProperty);
if (nodeType.isInstance(source))
nodes.add(nodeType.cast(source));
}
return nodes;
}
/**
For a Document created by {@link #fromJsoup(org.jsoup.nodes.Element)}, retrieves the W3C context node.
@param wDoc Document created by this class
@return the corresponding W3C Node to the jsoup Element that was used as the creating context.
*/
public Node contextNode(Document wDoc) {
return (Node) wDoc.getUserData(ContextNodeProperty);
}
/**
* Serialize a W3C document that was created by {@link #fromJsoup(org.jsoup.nodes.Element)} to a String.
* The output format will be XML or HTML depending on the content of the doc.
*
* @param doc Document
* @return Document as string
* @see W3CDom#asString(Document, Map)
*/
public String asString(Document doc) {
return asString(doc, null);
}
/**
* Implements the conversion by walking the input.
*/
protected static class W3CBuilder implements NodeVisitor {
private final Document doc;
// source bindings include omitted ancestors; output bindings track declarations emitted to the W3C tree
private final NamespaceBindings sourceNamespaces = new NamespaceBindings();
private final NamespaceBindings outputNamespaces = new NamespaceBindings();
private boolean namespaceAware = true;
private Node dest;
private Syntax syntax = Syntax.xml; // the syntax (to coerce attributes to). From the input doc if available.
/*@Nullable*/ private final org.jsoup.nodes.Element contextElement; // todo - unsure why this can't be marked nullable?
public W3CBuilder(Document doc) {
this.doc = doc;
dest = doc;
sourceNamespaces.put("xml", Parser.NamespaceXml);
outputNamespaces.put("xml", Parser.NamespaceXml);
contextElement = (org.jsoup.nodes.Element) doc.getUserData(ContextProperty); // Track the context jsoup Element, so we can save the corresponding w3c element
}
// Traverse only nodes supported as W3C document children, and keep the first element as the root.
private void traverseDocument(org.jsoup.nodes.Document source) {
org.jsoup.nodes.Element root = source.firstElementChild();
for (org.jsoup.nodes.Node child : source.childNodes()) {
if (child == root || child instanceof org.jsoup.nodes.DocumentType ||
child instanceof org.jsoup.nodes.Comment || child instanceof org.jsoup.nodes.XmlDeclaration)
traverse(child);
}
}
@Override
public void head(org.jsoup.nodes.Node source, int depth) {
if (source instanceof org.jsoup.nodes.Element)
appendElement((org.jsoup.nodes.Element) source, depth);
else if (source instanceof org.jsoup.nodes.DocumentType)
appendDocumentType((org.jsoup.nodes.DocumentType) source);
else if (source instanceof CDataNode)
appendCdata((CDataNode) source);
else if (source instanceof TextNode)
append(doc.createTextNode(((TextNode) source).getWholeText()), source);
else if (source instanceof Comment)
append(doc.createComment(((Comment) source).getData()), source);
else if (source instanceof DataNode)
append(doc.createTextNode(((DataNode) source).getWholeData()), source);
else if (source instanceof XmlDeclaration)
appendProcessingInstruction((XmlDeclaration) source);
}
/** Converts and appends an element, descending into its output node when representable. */
private void appendElement(org.jsoup.nodes.Element source, int depth) {
if (depth == 0)
seedSourceNamespaces(source);
sourceNamespaces.pushScope();
outputNamespaces.pushScope();
sourceNamespaces.applyDeclarations(source.attributes());
String namespace = namespaceAware ? w3cNamespace(source) : null;
String tagName = w3cSafeName(source.tagName(), Syntax.xml);
Element el;
try {
// use an empty namespace if none is present but the tag name has a prefix
String imputedNamespace = namespace == null && tagName.contains(":") ? "" : namespace;
el = doc.createElementNS(imputedNamespace, tagName);
} catch (DOMException ignored) {
// If the Normalize didn't get it XML / W3C safe, inserts as plain text
append(doc.createTextNode("<" + tagName + ">"), source);
return;
}
copyAttributes(source, el);
append(el, source);
if (source == contextElement)
doc.setUserData(ContextNodeProperty, el, null);
dest = el; // descend
}
// Keep the doctype in document order; invalid doctypes cannot be represented.
private void appendDocumentType(org.jsoup.nodes.DocumentType source) {
try {
DocumentType type = doc.getImplementation().createDocumentType(source.name(), source.publicId(), source.systemId());
append(type, source);
} catch (DOMException ignored) {
// invalid / empty doctype dropped
}
}
// Preserve CDATA where possible; programmatic content may be invalid for a W3C CDATA node.
private void appendCdata(org.jsoup.nodes.CDataNode source) {
try {
append(doc.createCDATASection(source.getWholeText()), source);
} catch (DOMException ignored) {
append(doc.createTextNode(source.getWholeText()), source);
}
}
// XmlDeclaration also represents <!name ...> nodes; XML declarations are reserved by the W3C DOM.
private void appendProcessingInstruction(org.jsoup.nodes.XmlDeclaration source) {
if (!source.outerHtml().startsWith("<?") || source.name().equalsIgnoreCase("xml")) return;
try {
append(doc.createProcessingInstruction(source.name(), source.getWholeDeclaration()), source);
} catch (DOMException ignored) {
// invalid programmatic processing instruction dropped
}
}
private static @Nullable String w3cNamespace(org.jsoup.nodes.Element sourceEl) {
// In W3C DOM, plain XML elements have no namespace; XML namespace is reserved for the {@code xml} prefix
String namespace = sourceEl.tag().namespace();
if (Parser.NamespaceXml.equals(namespace) && sourceEl.tag().prefix().isEmpty())
return null;
return namespace;
}
/** Applies declarations inherited from ancestors outside a subtree conversion. */
private void seedSourceNamespaces(org.jsoup.nodes.Element sourceEl) {
org.jsoup.select.Elements parents = sourceEl.parents();
for (int i = parents.size() - 1; i >= 0; i--) {
org.jsoup.nodes.Element parent = parents.get(i);
if (parent.attributesSize() > 0)
sourceNamespaces.applyDeclarations(parent.attributes());
}
}
private void append(Node append, org.jsoup.nodes.Node source) {
append.setUserData(SourceProperty, source, null);
dest.appendChild(append);
}
@Override
public void tail(org.jsoup.nodes.Node source, int depth) {
// head may emit an unrepresentable element as text without descending, so only ascend from its matching output element
if (source instanceof org.jsoup.nodes.Element && dest.getUserData(SourceProperty) == source &&
dest.getParentNode() != null) {
dest = dest.getParentNode(); // undescend
}
if (source instanceof org.jsoup.nodes.Element) {
sourceNamespaces.popScope();
outputNamespaces.popScope();
}
}
/** Copies namespace declarations first so source attribute order does not affect binding resolution. */
private void copyAttributes(org.jsoup.nodes.Element jEl, Element wEl) {
Attributes attributes = jEl.attributes();
for (Attribute attribute : attributes) {
if (NamespaceBindings.isDeclaration(attribute.getKey()))
copyAttribute(wEl, attribute);
}
for (Attribute attribute : attributes) {
if (!NamespaceBindings.isDeclaration(attribute.getKey()))
copyAttribute(wEl, attribute);
}
}
/** Copies an attribute using the closest W3C representation. */
private void copyAttribute(Element wEl, Attribute attribute) {
// preserve DOM-compatible HTML names; otherwise normalize as XML, and skip if still unrepresentable
if (!trySetAttribute(wEl, attribute, syntax) && syntax != Syntax.xml)
trySetAttribute(wEl, attribute, Syntax.xml);
}
/** Tries to copy an attribute, allowing the DOM to validate its name and namespace. */
private boolean trySetAttribute(Element wEl, Attribute attribute, Syntax syntax) {
try {
setAttribute(wEl, attribute, syntax);
return true;
} catch (DOMException ignored) {
return false;
}
}
/** Copies an attribute with its resolved namespace and W3C-safe name. */
private void setAttribute(Element wEl, Attribute attribute, Syntax syntax) throws DOMException {
String key = w3cSafeName(attribute.getKey(), syntax);
@Nullable String declarationPrefix = NamespaceBindings.declarationPrefix(key);
if (declarationPrefix != null) {
setNamespaceDeclaration(wEl, key, attribute.getValue());
outputNamespaces.put(declarationPrefix, attribute.getValue());
return;
}
int pos = key.indexOf(':');
if (pos == -1) { // default namespaces do not apply to unprefixed attributes
wEl.setAttribute(key, attribute.getValue());
return;
}
String prefix = key.substring(0, pos);
String sourcePrefix = attribute.prefix();
@Nullable String namespace;
if (namespaceAware) {
String attributeNamespace = attribute.namespace();
namespace = !attributeNamespace.isEmpty() ? attributeNamespace : sourceNamespaces.get(sourcePrefix);
} else {
namespace = sourceNamespaces.get(sourcePrefix);
}
if (namespace == null || namespace.isEmpty())
namespace = undefinedNs;
if (namespaceAware)
wEl.setAttributeNS(namespace, key, attribute.getValue());
else
wEl.setAttribute(key, attribute.getValue());
ensureOutputBinding(wEl, prefix, namespace);
}
/** Normalizes a name to a W3C-compatible QName, converting {@code 1:a:b} to {@code _1:a_b}. */
private String w3cSafeName(String name, Syntax syntax) {
String normalized = Attribute.getValidKey(name, syntax);
if (normalized.indexOf(':') == -1) return normalized;
Matcher parts = QNameParts.matcher(normalized);
if (!parts.matches()) return w3cSafeNcName(normalized.replace(':', '_'));
return w3cSafeNcName(parts.group(1)) + ':' + w3cSafeNcName(parts.group(2));
}
/** Normalizes one QName component while preserving valid XML name characters. */
private String w3cSafeNcName(String name) {
if (isValidNcName(name)) return name;
String safeStart = StringUtil.concat('_', name);
if (isValidNcName(safeStart)) return safeStart;
String colonSafe = name.replace(':', '_');
return Attribute.getValidKey(colonSafe, Syntax.xml);
}
/** Tests a component against the XML NCName rules used by the output DOM. */
private boolean isValidNcName(String name) {
try {
// validate as a local name so reserved words such as xmlns are treated as ordinary NCName text
doc.createAttributeNS(undefinedNs, "p:" + name);
return true;
} catch (DOMException ignored) {
return false;
}
}
/** Declares a prefix when its output binding is not active. */
private void ensureOutputBinding(Element wEl, String prefix, String namespace) {
if (!namespace.equals(outputNamespaces.get(prefix))) {
setNamespaceDeclaration(wEl, "xmlns:" + prefix, namespace);
outputNamespaces.put(prefix, namespace);
}
}
/** Writes a namespace declaration with namespace awareness when enabled. */
private void setNamespaceDeclaration(Element wEl, String key, String namespace) {
if (namespaceAware)
wEl.setAttributeNS(XMLConstants.XMLNS_ATTRIBUTE_NS_URI, key, namespace);
else
wEl.setAttribute(key, namespace);
}
private static final Pattern QNameParts = Pattern.compile("^([^:]+):(.+)$");
private static final String undefinedNs = "undefined";
}
}