001/**
002 *
003 * Copyright 2003-2007 Jive Software.
004 *
005 * Licensed under the Apache License, Version 2.0 (the "License");
006 * you may not use this file except in compliance with the License.
007 * You may obtain a copy of the License at
008 *
009 *     http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.jivesoftware.smack.packet;
019
020import java.util.*;
021
022import org.jivesoftware.smack.util.XmlStringBuilder;
023
024/**
025 * Default implementation of the PacketExtension interface. Unless a PacketExtensionProvider
026 * is registered with {@link org.jivesoftware.smack.provider.ProviderManager ProviderManager},
027 * instances of this class will be returned when getting packet extensions.<p>
028 *
029 * This class provides a very simple representation of an XML sub-document. Each element
030 * is a key in a Map with its CDATA being the value. For example, given the following
031 * XML sub-document:
032 *
033 * <pre>
034 * &lt;foo xmlns="http://bar.com"&gt;
035 *     &lt;color&gt;blue&lt;/color&gt;
036 *     &lt;food&gt;pizza&lt;/food&gt;
037 * &lt;/foo&gt;</pre>
038 *
039 * In this case, getValue("color") would return "blue", and getValue("food") would
040 * return "pizza". This parsing mechanism mechanism is very simplistic and will not work
041 * as desired in all cases (for example, if some of the elements have attributes. In those
042 * cases, a custom PacketExtensionProvider should be used.
043 *
044 * @author Matt Tucker
045 */
046public class DefaultPacketExtension implements PacketExtension {
047
048    private String elementName;
049    private String namespace;
050    private Map<String,String> map;
051
052    /**
053     * Creates a new generic packet extension.
054     *
055     * @param elementName the name of the element of the XML sub-document.
056     * @param namespace the namespace of the element.
057     */
058    public DefaultPacketExtension(String elementName, String namespace) {
059        this.elementName = elementName;
060        this.namespace = namespace;
061    }
062
063     /**
064     * Returns the XML element name of the extension sub-packet root element.
065     *
066     * @return the XML element name of the packet extension.
067     */
068    public String getElementName() {
069        return elementName;
070    }
071
072    /**
073     * Returns the XML namespace of the extension sub-packet root element.
074     *
075     * @return the XML namespace of the packet extension.
076     */
077    public String getNamespace() {
078        return namespace;
079    }
080
081    @Override
082    public CharSequence toXML() {
083        XmlStringBuilder buf = new XmlStringBuilder();
084        buf.halfOpenElement(elementName).xmlnsAttribute(namespace).rightAngelBracket();
085        for (String name : getNames()) {
086            String value = getValue(name);
087            buf.element(name, value);
088        }
089        buf.closeElement(elementName);
090        return buf;
091    }
092
093    /**
094     * Returns an unmodifiable collection of the names that can be used to get
095     * values of the packet extension.
096     *
097     * @return the names.
098     */
099    public synchronized Collection<String> getNames() {
100        if (map == null) {
101            return Collections.emptySet();
102        }
103        return Collections.unmodifiableSet(new HashMap<String,String>(map).keySet());
104    }
105
106    /**
107     * Returns a packet extension value given a name.
108     *
109     * @param name the name.
110     * @return the value.
111     */
112    public synchronized String getValue(String name) {
113        if (map == null) {
114            return null;
115        }
116        return map.get(name);
117    }
118
119    /**
120     * Sets a packet extension value using the given name.
121     *
122     * @param name the name.
123     * @param value the value.
124     */
125    public synchronized void setValue(String name, String value) {
126        if (map == null) {
127            map = new HashMap<String,String>();
128        }
129        map.put(name, value);
130    }
131}