Java tutorial
/** * Mule Google Api Commons * * Copyright (c) MuleSoft, Inc. All rights reserved. http://www.mulesoft.com * * The software in this package is published under the terms of the CPAL v1.0 * license, a copy of which has been included with this distribution in the * LICENSE.txt file. */ package com.google.gdata.model.transforms.atom; import static com.google.gdata.model.MetadataContext.RSS; import com.google.common.collect.Lists; import com.google.gdata.util.common.xml.XmlNamespace; import com.google.gdata.util.common.xml.XmlWriter; import com.google.gdata.util.common.xml.XmlWriter.Attribute; import com.google.gdata.data.DateTime; import com.google.gdata.data.ILink.Rel; import com.google.gdata.model.Element; import com.google.gdata.model.ElementMetadata; import com.google.gdata.model.MetadataRegistry; import com.google.gdata.model.MetadataValueTransform; import com.google.gdata.model.QName; import com.google.gdata.model.Metadata.VirtualValue; import com.google.gdata.model.atom.Author; import com.google.gdata.model.atom.Category; import com.google.gdata.model.atom.Content; import com.google.gdata.model.atom.Contributor; import com.google.gdata.model.atom.Entry; import com.google.gdata.model.atom.Feed; import com.google.gdata.model.atom.Link; import com.google.gdata.model.atom.OutOfLineContent; import com.google.gdata.model.atom.Person; import com.google.gdata.model.atom.Source; import com.google.gdata.model.atom.TextContent; import com.google.gdata.model.atom.Source.Generator; import com.google.gdata.model.atompub.Edited; import com.google.gdata.model.gd.GdAttributes; import com.google.gdata.util.ContentType; import com.google.gdata.util.Namespaces; import com.google.gdata.util.ParseException; import com.google.gdata.wireformats.XmlGenerator; import com.google.gdata.wireformats.XmlWireFormatProperties; import java.io.IOException; import java.net.URI; import java.util.ArrayList; import java.util.Collection; import java.util.Collections; import java.util.List; /** * RSS transforms for atom. This contains the transforms required to output * atom classes in RSS using the new data model. * * */ public class AtomRssTransforms { // Constants for our rss names. private static final QName DOMAIN = new QName("domain"); private static final QName CATEGORY = new QName(Namespaces.rssNs, "category"); private static final QName ITEM = new QName(Namespaces.rssNs, "item"); private static final QName GUID = new QName(Namespaces.rssNs, "guid"); private static final QName TITLE = new QName(Namespaces.rssNs, "title"); private static final QName PUB_DATE = new QName(Namespaces.rssNs, "pubDate"); private static final QName AUTHOR = new QName(Namespaces.rssNs, "author"); private static final QName RSS_NAME = new QName(Namespaces.rssNs, "rss"); private static final QName DESCRIPTION = new QName(Namespaces.rssNs, "description"); private static final QName LAST_BUILD_DATE = new QName(Namespaces.rssNs, "lastBuildDate"); private static final QName COPYRIGHT = new QName(Namespaces.rssNs, "copyright"); private static final QName MANAGING_EDITOR = new QName(Namespaces.rssNs, "managingEditor"); private static final QName GENERATOR = new QName(Namespaces.rssNs, "generator"); /** * Add the RSS transforms to the default metadata trees. */ public static void addTransforms(MetadataRegistry registry) { addCategoryTransforms(registry); addContentTransforms(registry); addEntryTransforms(registry); addEntryOutOfLineContentTransforms(registry); addFeedTransforms(registry); addLinkTransforms(registry); addSourceTransforms(registry); addPersonTransforms(registry); addGeneratorTransforms(registry); addAppEditedTransforms(registry); } private static void addCategoryTransforms(MetadataRegistry registry) { registry.build(Category.KEY, RSS).setName(CATEGORY) .setVirtualValue(new MetadataValueTransform(Category.TERM, Category.LABEL)); registry.build(Category.KEY, Category.SCHEME, RSS).setName(DOMAIN); registry.build(Category.KEY, Category.LABEL, RSS).setVisible(false); registry.build(Category.KEY, Category.TERM, RSS).setVisible(false); } private static void addContentTransforms(MetadataRegistry registry) { registry.build(TextContent.KEY, RSS).setName(DESCRIPTION).whitelistAttributes(); registry.build(TextContent.CONSTRUCT, RSS).whitelistAttributes(); } private static void addEntryTransforms(MetadataRegistry registry) { registry.build(Entry.KEY, RSS).setName(ITEM); registry.build(Entry.KEY, GdAttributes.ETAG, RSS).setVisible(false); XmlWireFormatProperties properties = new XmlWireFormatProperties(); properties.setElementGenerator(new XmlGenerator.XmlElementGenerator() { @Override protected List<Attribute> getAttributes(Element e, ElementMetadata<?, ?> metadata) { List<Attribute> attrs = super.getAttributes(e, metadata); if (attrs == null) { attrs = Lists.newArrayListWithExpectedSize(1); } attrs.add(new Attribute("isPermaLink", "false")); return attrs; } }); registry.build(Entry.KEY, Entry.ID, RSS).setName(GUID).setProperties(properties); registry.build(Entry.KEY, Entry.TITLE, RSS).setName(TITLE); registry.build(Entry.KEY, Entry.PUBLISHED, RSS).setName(PUB_DATE).setVirtualValue(new VirtualValue() { public Object generate(Element element, ElementMetadata<?, ?> metadata) { DateTime date = element.getTextValue(Entry.PUBLISHED); return date == null ? "" : date.toStringRfc822(); } public void parse(Element element, ElementMetadata<?, ?> metadata, Object value) throws ParseException { DateTime parsed = DateTime.parseRfc822(value.toString()); element.setTextValue(parsed); } }); XmlWireFormatProperties personProperties = new XmlWireFormatProperties(); personProperties.setElementGenerator(new XmlGenerator.XmlElementGenerator() { @Override public boolean startElement(XmlWriter xw, Element parent, Element e, ElementMetadata<?, ?> metadata) throws IOException { if (!(e instanceof Person)) { return super.startElement(xw, parent, e, metadata); } Person person = (Person) e; String email = person.getEmail(); String name = person.getName(); StringBuilder text = new StringBuilder(); boolean hasEmail = email != null; if (hasEmail) { text.append(email); } if (name != null) { if (hasEmail) { text.append(" ("); } text.append(name); if (hasEmail) { text.append(")"); } } QName xmlName = getName(e, metadata); xw.simpleElement(xmlName.getNs(), xmlName.getLocalName(), null, text.toString()); return false; } @Override public void textContent(XmlWriter xw, Element e, ElementMetadata<?, ?> metadata) { } @Override public void endElement(XmlWriter xw, Element e, ElementMetadata<?, ?> metadata) { } }); registry.build(Entry.KEY, Author.KEY, RSS).setName(AUTHOR).setProperties(personProperties); registry.build(Entry.KEY, Contributor.KEY, RSS).setName(AUTHOR).setProperties(personProperties); registry.build(Entry.KEY, Entry.RIGHTS, RSS).setVisible(false); } private static void addEntryOutOfLineContentTransforms(MetadataRegistry registry) { XmlWireFormatProperties properties = new XmlWireFormatProperties(); properties.setElementGenerator(new XmlGenerator.XmlElementGenerator() { @Override public boolean startElement(XmlWriter xw, Element parent, Element e, ElementMetadata<?, ?> metadata) throws IOException { if (!(e instanceof OutOfLineContent)) { return super.startElement(xw, parent, e, metadata); } OutOfLineContent content = (OutOfLineContent) e; ContentType type = content.getMimeType(); URI src = content.getSrc(); generateEnclosure(xw, type == null ? null : type.getMediaType(), src == null ? null : src.toString(), content.getLength()); return false; } @Override public void textContent(XmlWriter xw, Element e, ElementMetadata<?, ?> metadata) { } @Override public void endElement(XmlWriter xw, Element e, ElementMetadata<?, ?> metadata) { } }); registry.build(OutOfLineContent.KEY, RSS).setProperties(properties); } private static void addFeedTransforms(final MetadataRegistry registry) { registry.build(Feed.KEY, GdAttributes.ETAG, RSS).setVisible(false); XmlWireFormatProperties properties = new XmlWireFormatProperties(); properties.setElementGenerator(new XmlGenerator.XmlElementGenerator() { @Override public boolean startElement(XmlWriter xw, Element parent, Element e, ElementMetadata<?, ?> metadata) throws IOException { Collection<XmlNamespace> namespaces = getNamespaces(parent, e, metadata); List<XmlWriter.Attribute> attrs = getAttributes(e, metadata); if (attrs == null) { attrs = Lists.newArrayList(); } attrs.add(new Attribute("version", "2.0")); xw.startElement(Namespaces.rssNs, "rss", attrs, namespaces); xw.startElement(Namespaces.rssNs, "channel", null, null); if (!e.hasElement(Source.SUBTITLE) && !e.hasElement(Content.KEY)) { // To preserve strict RSS2 compliance and backward compatibility: // since atom feeds do not require a subtitle or text content, put in // an empty description into RSS. This keeps RSS2 validators happy xw.simpleElement(Namespaces.rssNs, "description", null, ""); } return true; } @Override public void endElement(XmlWriter xw, Element e, ElementMetadata<?, ?> metadata) throws IOException { xw.endElement(Namespaces.rssNs, "channel"); super.endElement(xw, e, metadata); } }); registry.build(Feed.KEY, RSS).setName(RSS_NAME).setProperties(properties); registry.build(Feed.KEY, Feed.UPDATED, RSS).setName(LAST_BUILD_DATE).setVirtualValue(new VirtualValue() { public Object generate(Element element, ElementMetadata<?, ?> metadata) { DateTime date = element.getTextValue(Feed.UPDATED); return date == null ? "" : date.toStringRfc822(); } public void parse(Element element, ElementMetadata<?, ?> metadata, Object value) throws ParseException { DateTime parsed = DateTime.parseRfc822(value.toString()); element.setTextValue(parsed); } }); } private static void addLinkTransforms(MetadataRegistry registry) { XmlWireFormatProperties properties = new XmlWireFormatProperties(); properties.setElementGenerator(new XmlGenerator.XmlElementGenerator() { @Override public boolean startElement(XmlWriter xw, Element parent, Element e, ElementMetadata<?, ?> metadata) throws IOException { if (!(e instanceof Link)) { return super.startElement(xw, parent, e, metadata); } Link link = (Link) e; String rel = link.getRel(); String type = link.getType(); String href = link.getHref(); long length = link.getLength(); if (rel != null && rel.equals("enclosure")) { generateEnclosure(xw, type, href, length); } else if ("comments".equals(rel)) { xw.simpleElement(Namespaces.rssNs, "comments", null, href); } else if (Rel.ALTERNATE.equals(rel)) { xw.simpleElement(Namespaces.rssNs, "link", null, href); } else if (Rel.VIA.equals(rel)) { if (href != null) { List<XmlWriter.Attribute> attrs = Collections .singletonList(new XmlWriter.Attribute("url", href)); xw.simpleElement(Namespaces.rssNs, "source", attrs, null); } } return false; } @Override public void textContent(XmlWriter xw, Element e, ElementMetadata<?, ?> metadata) { } @Override public void endElement(XmlWriter xw, Element e, ElementMetadata<?, ?> metadata) { } }); registry.build(Link.KEY, RSS).setProperties(properties); } private static void addSourceTransforms(MetadataRegistry registry) { registry.build(Source.CONSTRUCT, Source.TITLE, RSS).setName(TITLE); registry.build(Source.CONSTRUCT, Source.SUBTITLE, RSS).setName(DESCRIPTION); XmlWireFormatProperties properties = new XmlWireFormatProperties(); properties.setElementGenerator(new XmlGenerator.XmlElementGenerator() { @Override public boolean startElement(XmlWriter xw, Element parent, Element e, ElementMetadata<?, ?> metadata) throws IOException { boolean isIcon = e.getElementId().equals(Source.ICON.getId()); boolean isLogo = e.getElementId().equals(Source.LOGO.getId()); if ((!isIcon && !isLogo) || !(parent instanceof Source)) { return super.startElement(xw, parent, e, metadata); } Source source = (Source) parent; if (isIcon && source.hasElement(Source.LOGO)) { // atom:logo takes precedence return false; } xw.startElement(Namespaces.rssNs, "image", null, null); xw.simpleElement(Namespaces.rssNs, "url", null, String.valueOf(e.getTextValue())); TextContent title = source.getTitle(); if (title != null) { xw.simpleElement(Namespaces.rssNs, "title", null, title.getPlainText()); } Link htmlLink = source.getHtmlLink(); if (htmlLink != null) { xw.simpleElement(Namespaces.rssNs, "link", null, htmlLink.getHref()); } xw.endElement(Namespaces.rssNs, "image"); return false; } @Override public void textContent(XmlWriter xw, Element e, ElementMetadata<?, ?> metadata) { } @Override public void endElement(XmlWriter xw, Element e, ElementMetadata<?, ?> metadata) { } }); registry.build(Source.CONSTRUCT, Source.ICON, RSS).setProperties(properties); registry.build(Source.CONSTRUCT, Source.LOGO, RSS).setProperties(properties); registry.build(Source.CONSTRUCT, Source.RIGHTS, RSS).setVisible(true).setName(COPYRIGHT); registry.build(Source.CONSTRUCT, Author.KEY, RSS).setName(MANAGING_EDITOR) .setVirtualValue(new MetadataValueTransform(Person.NAME)); } private static void addPersonTransforms(MetadataRegistry registry) { registry.build(Person.KEY, Person.EMAIL, RSS).setVisible(false); registry.build(Person.KEY, Person.NAME, RSS).setVisible(false); registry.build(Person.KEY, Person.URI, RSS).setVisible(false); } private static void addGeneratorTransforms(MetadataRegistry registry) { registry.build(Generator.KEY, RSS).setName(GENERATOR); registry.build(Generator.KEY, Generator.URI, RSS).setVisible(false); registry.build(Generator.KEY, Generator.VERSION, RSS).setVisible(false); } private static void addAppEditedTransforms(MetadataRegistry registry) { registry.build(Edited.KEY, RSS).setVisible(false); } private static void generateEnclosure(XmlWriter xw, String type, String href, long length) throws IOException { List<XmlWriter.Attribute> attrs = new ArrayList<XmlWriter.Attribute>(3); if (type != null) { attrs.add(new XmlWriter.Attribute("type", type)); } if (href != null) { attrs.add(new XmlWriter.Attribute("url", href)); } // To preserve strict RSS2 compliance and backward compatibility: Since RSS // requires a length, then put it length=0 when the length is unknown. This // keeps RSS2 validators happy attrs.add(new XmlWriter.Attribute("length", Long.toString(length == -1 ? 0 : length))); xw.simpleElement(Namespaces.rssNs, "enclosure", attrs, null); } private AtomRssTransforms() { } }