atomservice.java

这个weblogging 设计得比较精巧

/*
 * Copyright 2005 David M Johnson (For RSS and Atom In Action)
 *
 * 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 org.roller.presentation.atomapi;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.jdom.Document;
import org.jdom.Element;
import org.jdom.Namespace;
import org.jdom.filter.Filter;

/**
 * This class models an Atom workspace.
 * 
 * @author Dave Johnson
 */
/*
 * Based on: draft-ietf-atompub-protocol-04.txt 
 * 
 * appService = 
 *    element app:service { 
 *       (appWorkspace* & anyElement* ) 
 *    }
 * 
 * Here is an example Atom workspace:
 * 
 * <?xml version="1.0" encoding='utf-8'?> 
 * <service
 *    xmlns="http://purl.org/atom/app#"> 
 *    <workspace title="Main Site" > 
 *       <collection
 *          contents="entries" title="My Blog Entries"
 *          href="http://example.org/reilly/feed" /> 
 *       <collection contents="generic"
 *          title="Documents" href="http://example.org/reilly/pic" /> 
 *    </workspace>
 *    <workspace title="Side Bar Blog"> 
 *       <collection contents="entries"
 *          title="Entries" href="http://example.org/reilly/feed" /> 
 *       <collection
 *          contents="http://example.net/booklist" title="Books"
 *          href="http://example.org/reilly/books" /> 
 *    </workspace> 
 * </service>
 */
public class AtomService
{
    public static final Namespace ns = 
        Namespace.getNamespace("http://purl.org/atom/app#");
    private List workspaces = new ArrayList();

    public AtomService()
    {
    }

    public void addWorkspace(AtomService.Workspace workspace)
    {
        workspaces.add(workspace);
    }

    public List getWorkspaces()
    {
        return workspaces;
    }

    public void setWorkspaces(List workspaces)
    {
        this.workspaces = workspaces;
    }

    /**
     * This class models an Atom workspace.
     * 
     * @author Dave Johnson
     */
    /*
     * appWorkspace = element app:workspace { attribute title { text }, (
     * appCollection* & anyElement* ) }
     */
    public static class Workspace
    {
        private String title       = null;
        private List   collections = new ArrayList();

        public Workspace()
        {
        }

        public List getCollections()
        {
            return collections;
        }

        public void setCollections(List collections)
        {
            this.collections = collections;
        }

        public void addCollection(AtomService.Collection col)
        {
            collections.add(col);
        }

        /** Workspace must have a human readable title */
        public String getTitle()
        {
            return title;
        }

        public void setTitle(String title)
        {
            this.title = title;
        }
    }

    /**
     * This class models an Atom workspace collection.
     * 
     * @author Dave Johnson
     */
    /*
     * appCollection = element app:collection { attribute title { text },
     * attribute contents { text }, attribute href { text }, anyElement* }
     */
    public static class Collection
    {
        private String title;
        private String contents = "generic";
        private String href;

        public Collection()
        {
        }

        /**
         * Contents attribute conveys the nature of a collection's member
         * resources. May be "entry" or "generic" and defaults to "generic"
         */
        public String getContents()
        {
            return contents;
        }

        public void setContents(String contents)
        {
            this.contents = contents;
        }

                /** The URI of the collection */
        public String getHref()
        {
            return href;
        }

        public void setHref(String href)
        {
            this.href = href;
        }

                /** Must have human readable title */
        public String getTitle()
        {
            return title;
        }

        public void setTitle(String title)
        {
            this.title = title;
        }
    }

    /** Deserialize an Atom service XML document into an object */
    public static AtomService documentToService(Document document)
    {
        AtomService service = new AtomService();
        Element root = document.getRootElement();
        List spaces = root.getChildren("workspace", ns);
        Iterator iter = spaces.iterator();
        while (iter.hasNext())
        {
            Element e = (Element) iter.next();
            service.addWorkspace(AtomService.elementToWorkspace(e));
        }
        return service;
    }

    /** Serialize an AtomService object into an XML document */
    public static Document serviceToDocument(AtomService service)
    {
        Document doc = new Document();
        Element root = new Element("service", ns);
        doc.setRootElement(root);
        Iterator iter = service.getWorkspaces().iterator();
        while (iter.hasNext())
        {
            AtomService.Workspace space = (AtomService.Workspace) iter.next();
            root.addContent(AtomService.workspaceToElement(space));
        }
        return doc;
    }

    /** Deserialize a Atom workspace XML element into an object */
    public static AtomService.Workspace elementToWorkspace(Element element)
    {
        AtomService.Workspace space = new AtomService.Workspace();
        space.setTitle(element.getAttribute("title").getValue());
        List collections = element.getChildren("collection", ns);
        Iterator iter = collections.iterator();
        while (iter.hasNext())
        {
            Element e = (Element) iter.next();
            space.addCollection(AtomService.elementToCollection(e));
        }
        return space;
    }

    /** Serialize an AtomService.Workspace object into an XML element */
    public static Element workspaceToElement(Workspace space)
    {
        Namespace ns = Namespace.getNamespace("http://purl.org/atom/app#");
        Element element = new Element("workspace", ns);
        element.setAttribute("title", space.getTitle());
        Iterator iter = space.getCollections().iterator();
        while (iter.hasNext())
        {
            AtomService.Collection col = (AtomService.Collection) iter.next();
            element.addContent(collectionToElement(col));
        }
        return element;
    }

    /** Deserialize an Atom service collection XML element into an object */
    public static AtomService.Collection elementToCollection(Element element)
    {
        AtomService.Collection collection = new AtomService.Collection();
        collection.setTitle(element.getAttribute("title").getValue());
        collection.setHref(element.getAttribute("href").getValue());
        if (element.getAttribute("href") != null)
        {
            collection.setContents(element.getAttribute("contents").getValue());
        }
        return collection;
    }

    /** Serialize an AtomService.Collection object into an XML element */
    public static Element collectionToElement(AtomService.Collection collection)
    {
        Namespace ns = Namespace.getNamespace("http://purl.org/atom/app#");
        Element element = new Element("collection", ns);
        element.setAttribute("title", collection.getTitle()); 
        element.setAttribute("href", collection.getHref());
        if (collection.getContents() != null)
        {
            element.setAttribute("contents", collection.getContents());
        }
        return element;
    }
}