Java tutorial
/******************************************************************************* * Copyright 2006 - 2012 Vienna University of Technology, * Department of Software Technology and Interactive Systems, IFS * * Licensed 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. ******************************************************************************/ package eu.scape_project.planning.xml; import java.io.IOException; import java.io.InputStream; import java.util.ArrayList; import java.util.List; import javax.xml.parsers.ParserConfigurationException; import javax.xml.parsers.SAXParser; import org.dom4j.Document; import org.dom4j.DocumentException; import org.dom4j.Element; import org.dom4j.Namespace; import org.dom4j.QName; import org.dom4j.io.SAXReader; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.xml.sax.ErrorHandler; import org.xml.sax.SAXException; import org.xml.sax.SAXParseException; import eu.scape_project.planning.model.FormatInfo; import eu.scape_project.planning.model.SampleObject; import eu.scape_project.planning.utils.ParserException; /** * A simple parser for the c3po profile. * * @author Petar Petrov - <me@petarpetrov.org> * */ public class C3POProfileParser { /** * The default namespace of a c3po profile. */ private static final String C3PO_NAMESPACE = "http://ifs.tuwien.ac.at/dp/c3po"; /** * A template for the description of the partition. */ private static final String TYPE_OF_OBJECTS_BEGIN = "The collection consists of {1}% '{2}' files. "; /** * A template for the second most prominent type of objects in the * partition. */ private static final String TYPE_OF_OBJECTS_SECOND = "It also contains {1}% '{2}' files. "; /** * A template for the conflicting objects in the partition. */ private static final String TYPE_OF_OBJECTS_CONFLICTS = "{1}% files have conflicts. "; /** * A template for the unknown objects in the partition. */ private static final String TYPE_OF_OBJECTS_UNKNOWN = "{1}% files have an unknown format. "; /** * A constant if the format distribution is missing. */ private static final String MISSING = "No format distribution provided"; /** * A template for the 'description of objects' field. */ private static final String DESCRIPTION_OF_SAMPLES_TEMPLATE = "The sample objects were chosen by c3po using the {1} algorithm."; private static final Logger log = LoggerFactory.getLogger(C3POProfileParser.class); private Document profile; private Namespace namespace; /** * Reads the profile out of the input stream and validates if needed. If the * document is faulty for some reason and exception will be thrown. * * @param stream * the stream of the c3po xml profile to read. * @param validate * whether or not to validate the xml. * @throws ParserException * if some error occurrs. */ public void read(final InputStream stream, boolean validate) throws ParserException { ValidatingParserFactory vpf = new ValidatingParserFactory(); SAXParser parser = null; try { parser = vpf.getValidatingParser(); } catch (ParserConfigurationException e) { log.error("An error occurred while parsing the c3po profile: {}", e.getMessage()); } catch (SAXException e) { log.error("An error occurred while parsing the c3po profile: {}", e.getMessage()); } if (validate && !this.isValid(parser, stream)) { throw new ParserException( "Validation was turned on, but the xml file is not valid against the schema."); } try { final SAXReader reader = new SAXReader(); this.profile = reader.read(stream); final Namespace namespace = this.profile.getRootElement().getNamespace(); if (!namespace.getStringValue().equals(C3PO_NAMESPACE)) { throw new ParserException("Cannot parse the profile, namespace does not match"); } } catch (final DocumentException e) { log.error("An error occurred while reading the profile: {}", e.getMessage()); this.profile = null; } try { stream.close(); } catch (final IOException e) { log.error("An error occurred while closing the input stream: {}", e.getMessage()); } } /** * Gets the collection identifier. * * @return the id. */ public String getCollectionId() { return this.profile.getRootElement().attributeValue("collection"); } /** * Gets the partition filter key (used by c3po). Note that only the first * partition is used. * * @return the partition filter key. */ public String getPartitionFilterKey() { return this.profile.getRootElement().element("partition").element("filter").attributeValue("id"); } /** * Gets the objects count in the partition. * * @return the count of objects. */ public String getObjectsCountInPartition() { return this.profile.getRootElement().element("partition").attributeValue("count"); } /** * Gets a human readable description of the objects in the form of * {@link C3POProfileParser#DESCRIPTION_OF_SAMPLES_TEMPLATE} * * @return */ public String getDescriptionOfObjects() { Element samples = (Element) this.profile.getRootElement().element("partition").element("samples"); String type = samples.attributeValue("type"); return DESCRIPTION_OF_SAMPLES_TEMPLATE.replace("{1}", type); } /** * Gets a human readable text description of the most prominent formats in * the profile. Traverses the properties of the profile until it finds the * format distribution. Then it takes the first two most occurring formats * (if existing). It also appends the percentage of conflicted and unknown * formats if any. * * @return the human readable description. */ public String getTypeOfObjects() { int count = Integer.parseInt(this.getObjectsCountInPartition()); QName name = new QName("format", this.namespace); List<Element> properties = this.profile.getRootElement().element("partition").element("properties") .elements("property"); List<Element> items = new ArrayList<Element>(); for (Element e : properties) { if (e.attributeValue("id").equals("format")) { items.addAll(e.elements()); break; } } if (items.isEmpty()) { return MISSING; } StringBuffer response = new StringBuffer(); String type; double tmp; double percent; if (items.size() >= 1) { Element item = items.remove(0); type = item.attributeValue("id"); tmp = Double.parseDouble(item.attributeValue("value")); percent = Math.floor((tmp / count) * 100); response.append(TYPE_OF_OBJECTS_BEGIN.replace("{1}", percent + "").replace("{2}", type)); } if (items.size() >= 1) {// already removed first Element item = items.remove(0); type = item.attributeValue("id"); tmp = Double.parseDouble(item.attributeValue("value")); percent = Math.floor((tmp / count) * 100); response.append(TYPE_OF_OBJECTS_SECOND.replace("{1}", percent + "").replace("{2}", type)); } for (Object o : items) { Element e = (Element) o; if (e.attributeValue("id").equals("Conflicted")) { tmp = Double.parseDouble(e.attributeValue("value")); percent = Math.floor((tmp / count) * 100); response.append(TYPE_OF_OBJECTS_CONFLICTS.replace("{1}", percent + "")); } else if (e.attributeValue("id").equals("Unknown")) { tmp = Double.parseDouble(e.attributeValue("value")); percent = Math.floor((tmp / count) * 100); response.append(TYPE_OF_OBJECTS_UNKNOWN.replace("{1}", percent + "")); } } return response.toString(); } /** * Gets a list of the sample objects and their metadata. * * @return the list of {@link SampleObject}s */ public List<SampleObject> getSampleObjects() { List<SampleObject> objects = new ArrayList<SampleObject>(); Element samples = this.profile.getRootElement().element("partition").element("samples"); for (Object s : samples.elements()) { Element sample = (Element) s; objects.add(this.parseSample(sample)); } return objects; } /** * Gets a list of proprietary identifiers as specified in the profile. * Depending on the use of the profile and whether or not the profile is * associated with a repository these identifiers can be different. The only * guarantee provided by the profile is that all uids are unique (within a * profile). * * @return a list of repository/file specific unique identifiers of the * objects in the collection. */ public List<String> getObjectIdentifiers() { List<String> uris = new ArrayList<String>(); List<Element> elements = this.profile.getRootElement().element("partition").element("elements") .elements("element"); for (Element e : elements) { uris.add(e.attributeValue("uid")); } return uris; } private SampleObject parseSample(Element sample) { String uid = sample.attributeValue("uid"); SampleObject sampleObject = new SampleObject(uid); sampleObject.setFullname(uid); List<Element> mimes = new ArrayList<Element>(); List<Element> size = new ArrayList<Element>(); List<Element> records = sample.elements("record"); for (Element rec : records) { if (rec.attributeValue("name").equals("mimetype")) { mimes.add(rec); } if (rec.attributeValue("name").equals("size")) { size.add(rec); } } if (mimes.size() > 1) { sampleObject.setContentType("Conflict"); } else if (mimes.size() == 1) { Element mimetype = (Element) mimes.get(0); sampleObject.setContentType(mimetype.attributeValue("value")); } if (size.size() == 1) { Element s = (Element) size.get(0); sampleObject.setSizeInBytes(Long.parseLong(s.attributeValue("value"))); } FormatInfo info = this.getFormatInfo(sample, sampleObject.getContentType()); sampleObject.setFormatInfo(info); return sampleObject; } private FormatInfo getFormatInfo(Element sample, String mime) { FormatInfo info = new FormatInfo(); info.setMimeType(mime); String uid = sample.attributeValue("uid"); List<Element> records = sample.elements("record"); List<Element> formats = new ArrayList<Element>(); List<Element> versions = new ArrayList<Element>(); List<Element> puids = new ArrayList<Element>(); for (Element rec : records) { if (rec.attributeValue("name").equals("format")) { formats.add(rec); } if (rec.attributeValue("name").equals("format_version")) { versions.add(rec); } if (rec.attributeValue("name").equals("puid")) { puids.add(rec); } } if (formats.size() > 1) { info.setName("Conflict"); } else if (formats.size() == 1) { Element format = (Element) formats.get(0); info.setName(format.attributeValue("value")); } if (versions.size() > 1) { info.setVersion("Conflict"); } else if (versions.size() == 1) { Element version = (Element) versions.get(0); info.setVersion(version.attributeValue("value")); } if (puids.size() > 1) { info.setPuid("Conflict"); } else if (puids.size() == 1) { Element puid = (Element) puids.get(0); info.setPuid(puid.attributeValue("value")); } return info; } // TODO read in the schema and if it is not of c3po - validate agains // the current schema of c3po. private boolean isValid(SAXParser parser, InputStream stream) { log.debug("validating collection profile"); try { SimpleErrorHandler errorHandler = new SimpleErrorHandler(); SAXReader reader = new SAXReader(parser.getXMLReader()); reader.setValidation(true); reader.setErrorHandler(errorHandler); reader.read(stream); return errorHandler.isValid(); } catch (SAXException e) { log.error("SAXException: {}", e.getMessage()); } catch (DocumentException e) { e.printStackTrace(); log.error("DocumentException: {}", e.getMessage()); } catch (NullPointerException e) { log.warn("Factory is not initialized. Did you call init()"); } return false; } /** * A simple error handler to catch if the xml document has some errors. * * @author Petar Petrov - <me@petarpetrov.org> * */ private class SimpleErrorHandler implements ErrorHandler { private boolean valid; public SimpleErrorHandler() { this.valid = true; } @Override public void error(SAXParseException e) throws SAXException { log.error("Error: {}", e.getMessage()); this.valid = false; } @Override public void fatalError(SAXParseException e) throws SAXException { log.error("Fatal Error: {}", e.getMessage()); this.valid = false; } @Override public void warning(SAXParseException e) throws SAXException { log.error("Warning: {}", e.getMessage()); } public boolean isValid() { return this.valid; } } }