src/main/java/org/apache/xmlgraphics/xmp/XMPHandler.java - xmlgraphics-commons - Git at Google

 /*
  * 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.
  */

 /* $Id$ */

 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");
             }
             if (getCurrentProperties() == null) {
                 startStructure();
             }
             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);
     }

 }
	/*
	* 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.
	*/

	/* $Id$ */

	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");
	}
	if (getCurrentProperties() == null) {
	startStructure();
	}
	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);
	}

	}