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Apache XML Graphics Commons is a library that consists of several reusable
components used by Apache Batik and Apache FOP. Many of these components
can easily be used separately outside the domains of SVG and XSL-FO.
/*
* 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.
*/
/* $Id: XMPHandler.java 1681108 2015-05-22 13:26:12Z ssteiner $ */
package org.apache.xmlgraphics.xmp;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.Stack;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.AttributesImpl;
import org.xml.sax.helpers.DefaultHandler;
import org.apache.xmlgraphics.util.QName;
/**
* Passive XMP parser implemented as a SAX DefaultHandler. After the XML document has been parsed
* the Metadata object can be retrieved.
*/
public class XMPHandler extends DefaultHandler {
private Metadata meta;
private StringBuffer content = new StringBuffer();
private Stack attributesStack = new Stack();
private Stack nestingInfoStack = new Stack();
private Stack contextStack = new Stack();
/** @return the parsed metadata, available after the parsing. */
public Metadata getMetadata() {
return this.meta;
}
private boolean hasComplexContent() {
Object obj = this.contextStack.peek();
return !(obj instanceof QName);
}
private PropertyAccess getCurrentProperties() {
Object obj = this.contextStack.peek();
if (obj instanceof PropertyAccess) {
return (PropertyAccess)obj;
} else {
return null;
}
}
private QName getCurrentPropName() {
Object obj = this.contextStack.peek();
if (obj instanceof QName) {
return (QName)obj;
} else {
return null;
}
}
private QName popCurrentPropName() throws SAXException {
Object obj = this.contextStack.pop();
this.nestingInfoStack.pop();
if (obj instanceof QName) {
return (QName)obj;
} else {
throw new SAXException("Invalid XMP structure. Property name expected");
}
}
// private XMPComplexValue getCurrentComplexValue() {
// Object obj = this.contextStack.peek();
// if (obj instanceof XMPComplexValue) {
// return (XMPComplexValue)obj;
// } else {
// return null;
// }
// }
private XMPStructure getCurrentStructure() {
Object obj = this.contextStack.peek();
if (obj instanceof XMPStructure) {
return (XMPStructure)obj;
} else {
return null;
}
}
private XMPArray getCurrentArray(boolean required) throws SAXException {
Object obj = this.contextStack.peek();
if (obj instanceof XMPArray) {
return (XMPArray)obj;
} else {
if (required) {
throw new SAXException("Invalid XMP structure. Not in array");
} else {
return null;
}
}
}
// --- Overrides ---
/** {@inheritDoc} */
public void startElement(String uri, String localName, String qName, Attributes attributes)
throws SAXException {
super.startElement(uri, localName, qName, attributes);
content.setLength(0); //Reset text buffer (see characters())
attributesStack.push(new AttributesImpl(attributes));
if (XMPConstants.XMP_NAMESPACE.equals(uri)) {
if (!"xmpmeta".equals(localName)) {
throw new SAXException("Expected x:xmpmeta element, not " + qName);
}
if (this.meta != null) {
throw new SAXException("Invalid XMP document. Root already received earlier.");
}
this.meta = new Metadata();
this.contextStack.push(this.meta);
this.nestingInfoStack.push("metadata");
} else if (XMPConstants.RDF_NAMESPACE.equals(uri)) {
if ("RDF".equals(localName)) {
if (this.meta == null) {
this.meta = new Metadata();
this.contextStack.push(this.meta);
this.nestingInfoStack.push("metadata");
}
} else if ("Description".equals(localName)) {
String about = attributes.getValue(XMPConstants.RDF_NAMESPACE, "about");
for (int i = 0, c = attributes.getLength(); i < c; i++) {
String ns = attributes.getURI(i);
if (XMPConstants.RDF_NAMESPACE.equals(ns)) {
//ignore
} else if (XMPConstants.XMLNS_NAMESPACE.equals(ns)) {
//ignore
} else if ("".equals(ns)) {
//ignore
} else {
String qn = attributes.getQName(i);
String v = attributes.getValue(i);
XMPProperty prop = new XMPProperty(new QName(ns, qn), v);
getCurrentProperties().setProperty(prop);
}
}
if (this.contextStack.peek().equals(this.meta)) {
//rdf:RDF is the parent
} else {
if (about != null) {
throw new SAXException(
"Nested rdf:Description elements may not have an about property");
}
startStructure();
}
} else if ("Seq".equals(localName)) {
XMPArray array = new XMPArray(XMPArrayType.SEQ);
this.contextStack.push(array);
this.nestingInfoStack.push("Seq");
} else if ("Bag".equals(localName)) {
XMPArray array = new XMPArray(XMPArrayType.BAG);
this.contextStack.push(array);
this.nestingInfoStack.push("Bag");
} else if ("Alt".equals(localName)) {
XMPArray array = new XMPArray(XMPArrayType.ALT);
this.contextStack.push(array);
this.nestingInfoStack.push("Alt");
} else if ("li".equals(localName)) {
//nop, handle in endElement()
} else if ("value".equals(localName)) {
QName name = new QName(uri, qName);
this.contextStack.push(name);
this.nestingInfoStack.push("prop:" + name);
} else {
throw new SAXException("Unexpected element in the RDF namespace: " + localName);
}
} else {
if (getCurrentPropName() != null) {
//Structure (shorthand form)
startStructure();
}
QName name = new QName(uri, qName);
this.contextStack.push(name);
this.nestingInfoStack.push("prop:" + name);
}
}
private void startStructure() {
//a structured property is the parent
XMPStructure struct = new XMPStructure();
this.contextStack.push(struct);
this.nestingInfoStack.push("struct");
}
/** {@inheritDoc} */
public void endElement(String uri, String localName, String qName) throws SAXException {
Attributes atts = (Attributes)attributesStack.pop();
if (XMPConstants.XMP_NAMESPACE.equals(uri)) {
//nop
} else if (XMPConstants.RDF_NAMESPACE.equals(uri) && !"value".equals(localName)) {
if ("li".equals(localName)) {
XMPStructure struct = getCurrentStructure();
if (struct != null) {
//Pop the structure
this.contextStack.pop();
this.nestingInfoStack.pop();
getCurrentArray(true).add(struct);
} else {
String s = content.toString().trim();
if (s.length() > 0) {
String lang = atts.getValue(XMPConstants.XML_NS, "lang");
if (lang != null) {
getCurrentArray(true).add(s, lang);
} else {
getCurrentArray(true).add(s);
}
} else {
String res = atts.getValue(XMPConstants.RDF_NAMESPACE,
"resource");
if (res != null) {
try {
URI resource = new URI(res);
getCurrentArray(true).add(resource);
} catch (URISyntaxException e) {
throw new SAXException("rdf:resource value is not a well-formed URI", e);
}
}
}
}
} else if ("Description".equals(localName)) {
/*
if (isInStructure()) {
//Description is indicating a structure
//this.currentProperties = (PropertyAccess)propertiesStack.pop();
this.nestingInfoStack.pop();
}*/
} else {
//nop, don't pop stack so the parent element has access
}
} else {
XMPProperty prop;
QName name;
if (hasComplexContent()) {
//Pop content of property
Object obj = this.contextStack.pop();
this.nestingInfoStack.pop();
name = popCurrentPropName();
if (obj instanceof XMPComplexValue) {
XMPComplexValue complexValue = (XMPComplexValue)obj;
prop = new XMPProperty(name, complexValue);
} else {
throw new UnsupportedOperationException("NYI");
}
} else {
name = popCurrentPropName();
String s = content.toString().trim();
prop = new XMPProperty(name, s);
String lang = atts.getValue(XMPConstants.XML_NS, "lang");
String res = atts.getValue(XMPConstants.RDF_NAMESPACE, "resource");
if (lang != null) {
prop.setXMLLang(lang);
}
if (res != null) {
try {
URI resource = new URI(res);
prop.setValue(resource);
} catch (URISyntaxException e) {
throw new SAXException("rdf:resource value is not a well-formed URI", e);
}
}
}
if (prop.getName() == null) {
throw new IllegalStateException("No content in XMP property");
}
assert getCurrentProperties() != null : "no current property";
getCurrentProperties().setProperty(prop);
}
content.setLength(0); //Reset text buffer (see characters())
super.endElement(uri, localName, qName);
}
/*
private boolean isInStructure() {
return !propertiesStack.isEmpty();
}
*/
/** {@inheritDoc} */
public void characters(char[] ch, int start, int length) throws SAXException {
content.append(ch, start, length);
}
}