| package org.apache.commons.digester3; |
| |
| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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. |
| */ |
| |
| import javax.xml.parsers.DocumentBuilder; |
| import javax.xml.parsers.DocumentBuilderFactory; |
| import javax.xml.parsers.ParserConfigurationException; |
| |
| import org.w3c.dom.Attr; |
| import org.w3c.dom.DOMException; |
| import org.w3c.dom.Document; |
| import org.w3c.dom.Element; |
| import org.w3c.dom.Node; |
| import org.xml.sax.Attributes; |
| import org.xml.sax.ContentHandler; |
| import org.xml.sax.SAXException; |
| import org.xml.sax.helpers.DefaultHandler; |
| |
| /** |
| * A rule implementation that creates a DOM {@link org.w3c.dom.Node Node} containing the XML at the element that matched |
| * the rule. Two concrete types of nodes can be created by this rule: |
| * <ul> |
| * <li>the default is to create an {@link org.w3c.dom.Element Element} node. The created element will correspond to the |
| * element that matched the rule, containing all XML content underneath that element.</li> |
| * <li>alternatively, this rule can create nodes of type {@link org.w3c.dom.DocumentFragment DocumentFragment}, which |
| * will contain only the XML content under the element the rule was trigged on.</li> |
| * </ul> |
| * The created node will be normalized, meaning it will not contain text nodes that only contain white space characters. |
| * <p> |
| * The created <code>Node</code> will be pushed on Digester's object stack when done. To use it in the context of |
| * another DOM {@link org.w3c.dom.Document Document}, it must be imported first, using the Document method |
| * {@link org.w3c.dom.Document#importNode(org.w3c.dom.Node, boolean) importNode()}. |
| * </p> |
| * <p> |
| * <strong>Important Note:</strong> This is implemented by replacing the SAX {@link org.xml.sax.ContentHandler |
| * ContentHandler} in the parser used by Digester, and resetting it when the matched element is closed. As a side |
| * effect, rules that would match XML nodes under the element that matches a <code>NodeCreateRule</code> will never be |
| * triggered by Digester, which usually is the behavior one would expect. |
| * </p> |
| * <p> |
| * <strong>Note</strong> that the current implementation does not set the namespace prefixes in the exported nodes. The |
| * (usually more important) namespace URIs are set, of course. |
| * </p> |
| * |
| * @since Digester 1.4 |
| */ |
| public class NodeCreateRule |
| extends Rule |
| { |
| |
| // ---------------------------------------------------------- Inner Classes |
| |
| /** |
| * The SAX content handler that does all the actual work of assembling the DOM node tree from the SAX events. |
| */ |
| private class NodeBuilder |
| extends DefaultHandler |
| { |
| |
| // ------------------------------------------------------- Constructors |
| |
| /** |
| * Constructor. |
| * <p> |
| * Stores the content handler currently used by Digester so it can be reset when done, and initializes the DOM |
| * objects needed to build the node. |
| * </p> |
| * |
| * @param doc the document to use to create nodes |
| * @param root the root node |
| * @throws ParserConfigurationException if the DocumentBuilderFactory could not be instantiated |
| * @throws SAXException if the XMLReader could not be instantiated by Digester (should not happen) |
| */ |
| public NodeBuilder( final Document doc, final Node root ) |
| throws ParserConfigurationException, SAXException |
| { |
| this.doc = doc; |
| this.root = root; |
| this.top = root; |
| |
| oldContentHandler = getDigester().getCustomContentHandler(); |
| } |
| |
| // ------------------------------------------------- Instance Variables |
| |
| /** |
| * The content handler used by Digester before it was set to this content handler. |
| */ |
| protected ContentHandler oldContentHandler = null; |
| |
| /** |
| * Depth of the current node, relative to the element where the content handler was put into action. |
| */ |
| protected int depth = 0; |
| |
| /** |
| * A DOM Document used to create the various Node instances. |
| */ |
| protected Document doc = null; |
| |
| /** |
| * The DOM node that will be pushed on Digester's stack. |
| */ |
| protected Node root = null; |
| |
| /** |
| * The current top DOM mode. |
| */ |
| protected Node top = null; |
| |
| /** |
| * The text content of the current top DOM node. |
| */ |
| protected StringBuilder topText = new StringBuilder(); |
| |
| // --------------------------------------------- Helper Methods |
| |
| /** |
| * Appends a {@link org.w3c.dom.Text Text} node to the current node if the content reported by the parser is not |
| * purely whitespace. |
| */ |
| private void addTextIfPresent() |
| throws SAXException |
| { |
| if ( topText.length() > 0 ) |
| { |
| final String str = topText.toString(); |
| topText.setLength( 0 ); |
| |
| if ( !str.trim().isEmpty() ) |
| { |
| // The contained text is not *pure* whitespace, so create |
| // a text node to hold it. Note that the "untrimmed" text |
| // is stored in the node. |
| try |
| { |
| top.appendChild( doc.createTextNode( str ) ); |
| } |
| catch ( final DOMException e ) |
| { |
| throw new SAXException( e.getMessage() ); |
| } |
| } |
| } |
| } |
| |
| // --------------------------------------------- ContentHandler Methods |
| |
| /** |
| * Handle notification about text embedded within the current node. |
| * <p> |
| * An xml parser calls this when text is found. We need to ensure that this text gets attached to the new Node |
| * we are creating - except in the case where the only text in the node is whitespace. |
| * <p> |
| * There is a catch, however. According to the sax specification, a parser does not need to pass all of the text |
| * content of a node in one go; it can make multiple calls passing part of the data on each call. In particular, |
| * when the body of an element includes xml entity-references, at least some parsers make a separate call to |
| * this method to pass just the entity content. |
| * <p> |
| * In this method, we therefore just append the provided text to a "current text" buffer. When the element end |
| * is found, or a child element is found then we can check whether we have all-whitespace. See method |
| * addTextIfPresent. |
| * |
| * @param ch the characters from the XML document |
| * @param start the start position in the array |
| * @param length the number of characters to read from the array |
| * @throws SAXException if the DOM implementation throws an exception |
| */ |
| @Override |
| public void characters( final char[] ch, final int start, final int length ) |
| throws SAXException |
| { |
| topText.append( ch, start, length ); |
| } |
| |
| /** |
| * Checks whether control needs to be returned to Digester. |
| * |
| * @param namespaceURI the namespace URI |
| * @param localName the local name |
| * @param qName the qualified (prefixed) name |
| * @throws SAXException if the DOM implementation throws an exception |
| */ |
| @Override |
| public void endElement( final String namespaceURI, final String localName, final String qName ) |
| throws SAXException |
| { |
| addTextIfPresent(); |
| |
| try |
| { |
| if ( depth == 0 ) |
| { |
| getDigester().setCustomContentHandler( oldContentHandler ); |
| getDigester().push( root ); |
| getDigester().endElement( namespaceURI, localName, qName ); |
| } |
| |
| top = top.getParentNode(); |
| depth--; |
| } |
| catch ( final DOMException e ) |
| { |
| throw new SAXException( e.getMessage() ); |
| } |
| } |
| |
| /** |
| * Adds a new {@link org.w3c.dom.ProcessingInstruction ProcessingInstruction} to the current node. |
| * |
| * @param target the processing instruction target |
| * @param data the processing instruction data, or null if none was supplied |
| * @throws SAXException if the DOM implementation throws an exception |
| */ |
| @Override |
| public void processingInstruction( final String target, final String data ) |
| throws SAXException |
| { |
| try |
| { |
| top.appendChild( doc.createProcessingInstruction( target, data ) ); |
| } |
| catch ( final DOMException e ) |
| { |
| throw new SAXException( e.getMessage() ); |
| } |
| } |
| |
| /** |
| * Adds a new child {@link org.w3c.dom.Element Element} to the current node. |
| * |
| * @param namespaceURI the namespace URI |
| * @param localName the local name |
| * @param qName the qualified (prefixed) name |
| * @param atts the list of attributes |
| * @throws SAXException if the DOM implementation throws an exception |
| */ |
| @Override |
| public void startElement( final String namespaceURI, final String localName, final String qName, final Attributes atts ) |
| throws SAXException |
| { |
| addTextIfPresent(); |
| |
| try |
| { |
| final Node previousTop = top; |
| if ( ( localName == null ) || ( localName.isEmpty() ) ) |
| { |
| top = doc.createElement( qName ); |
| } |
| else |
| { |
| top = doc.createElementNS( namespaceURI, localName ); |
| } |
| for ( int i = 0; i < atts.getLength(); i++ ) |
| { |
| Attr attr = null; |
| if ( ( atts.getLocalName( i ) == null ) || ( atts.getLocalName( i ).isEmpty() ) ) |
| { |
| attr = doc.createAttribute( atts.getQName( i ) ); |
| attr.setNodeValue( atts.getValue( i ) ); |
| ( (Element) top ).setAttributeNode( attr ); |
| } |
| else |
| { |
| attr = doc.createAttributeNS( atts.getURI( i ), atts.getLocalName( i ) ); |
| attr.setNodeValue( atts.getValue( i ) ); |
| ( (Element) top ).setAttributeNodeNS( attr ); |
| } |
| } |
| previousTop.appendChild( top ); |
| depth++; |
| } |
| catch ( final DOMException e ) |
| { |
| throw new SAXException( e.getMessage() ); |
| } |
| } |
| } |
| |
| // ----------------------------------------------------------- Constructors |
| |
| /** |
| * Default constructor. Creates an instance of this rule that will create a DOM {@link org.w3c.dom.Element Element}. |
| * |
| * @throws ParserConfigurationException if a DocumentBuilder cannot be created which satisfies the |
| * configuration requested. |
| * @see DocumentBuilderFactory#newDocumentBuilder() |
| */ |
| public NodeCreateRule() |
| throws ParserConfigurationException |
| { |
| this( Node.ELEMENT_NODE ); |
| } |
| |
| /** |
| * Constructor. Creates an instance of this rule that will create a DOM {@link org.w3c.dom.Element Element}, but |
| * lets you specify the JAXP <code>DocumentBuilder</code> that should be used when constructing the node tree. |
| * |
| * @param documentBuilder the JAXP <code>DocumentBuilder</code> to use |
| */ |
| public NodeCreateRule( final DocumentBuilder documentBuilder ) |
| { |
| this( Node.ELEMENT_NODE, documentBuilder ); |
| } |
| |
| /** |
| * Constructor. Creates an instance of this rule that will create either a DOM {@link org.w3c.dom.Element Element} |
| * or a DOM {@link org.w3c.dom.DocumentFragment DocumentFragment}, depending on the value of the |
| * <code>nodeType</code> parameter. |
| * |
| * @param nodeType the type of node to create, which can be either {@link org.w3c.dom.Node#ELEMENT_NODE |
| * Node.ELEMENT_NODE} or {@link org.w3c.dom.Node#DOCUMENT_FRAGMENT_NODE Node.DOCUMENT_FRAGMENT_NODE} |
| * @throws ParserConfigurationException if a DocumentBuilder cannot be created which satisfies the |
| * configuration requested. |
| * @see DocumentBuilderFactory#newDocumentBuilder() |
| */ |
| public NodeCreateRule( final int nodeType ) |
| throws ParserConfigurationException |
| { |
| this( nodeType, DocumentBuilderFactory.newInstance().newDocumentBuilder() ); |
| } |
| |
| /** |
| * Constructor. Creates an instance of this rule that will create either a DOM {@link org.w3c.dom.Element Element} |
| * or a DOM {@link org.w3c.dom.DocumentFragment DocumentFragment}, depending on the value of the |
| * <code>nodeType</code> parameter. This constructor lets you specify the JAXP <code>DocumentBuilder</code> that |
| * should be used when constructing the node tree. |
| * |
| * @param nodeType the type of node to create, which can be either {@link org.w3c.dom.Node#ELEMENT_NODE |
| * Node.ELEMENT_NODE} or {@link org.w3c.dom.Node#DOCUMENT_FRAGMENT_NODE Node.DOCUMENT_FRAGMENT_NODE} |
| * @param documentBuilder the JAXP <code>DocumentBuilder</code> to use |
| */ |
| public NodeCreateRule( final int nodeType, final DocumentBuilder documentBuilder ) |
| { |
| if ( !( ( nodeType == Node.DOCUMENT_FRAGMENT_NODE ) || ( nodeType == Node.ELEMENT_NODE ) ) ) |
| { |
| throw new IllegalArgumentException( "Can only create nodes of type DocumentFragment and Element" ); |
| } |
| this.nodeType = nodeType; |
| this.documentBuilder = documentBuilder; |
| } |
| |
| // ----------------------------------------------------- Instance Variables |
| |
| /** |
| * The JAXP <code>DocumentBuilder</code> to use. |
| */ |
| private DocumentBuilder documentBuilder = null; |
| |
| /** |
| * The type of the node that should be created. Must be one of the constants defined in {@link org.w3c.dom.Node |
| * Node}, but currently only {@link org.w3c.dom.Node#ELEMENT_NODE Node.ELEMENT_NODE} and |
| * {@link org.w3c.dom.Node#DOCUMENT_FRAGMENT_NODE Node.DOCUMENT_FRAGMENT_NODE} are allowed values. |
| */ |
| private int nodeType = Node.ELEMENT_NODE; |
| |
| // ----------------------------------------------------------- Rule Methods |
| |
| /** |
| * When this method fires, the digester is told to forward all SAX ContentHandler events to the builder object, |
| * resulting in a DOM being built instead of normal digester rule-handling occurring. When the end of the current |
| * xml element is encountered, the original content handler is restored (expected to be NULL, allowing normal |
| * Digester operations to continue). |
| * |
| * @param namespaceURI the namespace URI of the matching element, or an empty string if the parser is not namespace |
| * aware or the element has no namespace |
| * @param name the local name if the parser is namespace aware, or just the element name otherwise |
| * @param attributes The attribute list of this element |
| * @throws Exception indicates a JAXP configuration problem |
| */ |
| @Override |
| public void begin( final String namespaceURI, final String name, final Attributes attributes ) |
| throws Exception |
| { |
| final Document doc = documentBuilder.newDocument(); |
| NodeBuilder builder = null; |
| if ( nodeType == Node.ELEMENT_NODE ) |
| { |
| Element element = null; |
| if ( getDigester().getNamespaceAware() ) |
| { |
| element = doc.createElementNS( namespaceURI, name ); |
| for ( int i = 0; i < attributes.getLength(); i++ ) |
| { |
| element.setAttributeNS( attributes.getURI( i ), attributes.getQName( i ), |
| attributes.getValue( i ) ); |
| } |
| } |
| else |
| { |
| element = doc.createElement( name ); |
| for ( int i = 0; i < attributes.getLength(); i++ ) |
| { |
| element.setAttribute( attributes.getQName( i ), attributes.getValue( i ) ); |
| } |
| } |
| builder = new NodeBuilder( doc, element ); |
| } |
| else |
| { |
| builder = new NodeBuilder( doc, doc.createDocumentFragment() ); |
| } |
| // the NodeBuilder constructor has already saved the original |
| // value of the digester's custom content handler (expected to |
| // be null, but we save it just in case). So now we just |
| // need to tell the digester to forward events to the builder. |
| getDigester().setCustomContentHandler( builder ); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public void end( final String namespace, final String name ) |
| throws Exception |
| { |
| getDigester().pop(); |
| } |
| |
| } |
