SMACK-272 Add support for XEP-0060 (pubsub)

git-svn-id: http://svn.igniterealtime.org/svn/repos/smack/trunk@11346 b35dd754-fafc-0310-a699-88a17e54d16e

source/org/jivesoftware/smackx/pubsub/Item.java

@@ -0,0 +1,109 @@
+/**
+ * All rights reserved. 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.jivesoftware.smackx.pubsub;
+
+import org.jivesoftware.smack.packet.PacketExtension;
+import org.jivesoftware.smackx.pubsub.provider.ItemProvider;
+
+/**
+ * This class represents an item that has been, or will be published to a
+ * pubsub node.  An <tt>Item</tt> has several properties that are dependent
+ * on the configuration of the node to which it has been or will be published.
+ * 
+ * <h1>An Item received from a node (via {@link LeafNode#getItems()} or {@link LeafNode#addItemEventListener(org.jivesoftware.smackx.pubsub.listener.ItemEventListener)}</b>
+ * <li>Will always have an id (either user or server generated) unless node configuration has both
+ * {@link ConfigureForm#isPersistItems()} and {@link ConfigureForm#isDeliverPayloads()}set to false.
+ * <li>Will have a payload if the node configuration has {@link ConfigureForm#isDeliverPayloads()} set 
+ * to true, otherwise it will be null.
+ * 
+ * <h1>An Item created to send to a node (via {@link LeafNode#send()} or {@link LeafNode#publish()}</b>
+ * <li>The id is optional, since the server will generate one if necessary, but should be used if it is 
+ * meaningful in the context of the node.  This value must be unique within the node that it is sent to, since
+ * resending an item with the same id will overwrite the one that already exists if the items are persisted.
+ * <li>Will require payload if the node configuration has {@link ConfigureForm#isDeliverPayloads()} set
+ * to true. 
+ * 
+ * <p>To customise the payload object being returned from the {@link #getPayload()} method, you can
+ * add a custom parser as explained in {@link ItemProvider}.
+ * 
+ * @author Robin Collier
+ */
+public class Item implements PacketExtension
+{
+	private String id;
+	
+	/**
+	 * Create an empty <tt>Item</tt> with no id.  This is a valid item for nodes which are configured
+	 * so that {@link ConfigureForm#isDeliverPayloads()} is false.  In most cases an id will be generated by the server.
+	 * For nodes configured with {@link ConfigureForm#isDeliverPayloads()} and {@link ConfigureForm#isPersistItems()} 
+	 * set to false, no <tt>Item</tt> is sent to the node, you have to use {@link LeafNode#send()} or {@link LeafNode#publish()}
+	 * methods in this case. 
+	 */
+	public Item()
+	{
+	}
+	
+	/**
+	 * Create an <tt>Item</tt> with an id but no payload.  This is a valid item for nodes which are configured
+	 * so that {@link ConfigureForm#isDeliverPayloads()} is false.
+	 * 
+	 * @param itemId The id if the item.  It must be unique within the node unless overwriting and existing item.
+	 * Passing null is the equivalent of calling {@link #Item()}.
+	 */
+	public Item(String itemId)
+	{
+		id = itemId;
+	}
+	
+	/**
+	 * Get the item id.  Unique to the node it is associated with.
+	 * 
+	 * @return The id
+	 */
+	public String getId()
+	{
+		return id;
+	}
+	
+	public String getElementName()
+	{
+		return "item";
+	}
+
+	public String getNamespace()
+	{
+		return null;
+	}
+
+	public String toXML()
+	{
+		StringBuilder builder = new StringBuilder("<item");
+		
+		if (id != null)
+		{
+			builder.append(" id='");
+			builder.append(id);
+			builder.append("'");
+		}
+		builder.append("/>");
+
+		return builder.toString();
+	}
+
+	@Override
+	public String toString()
+	{
+		return getClass().getName() + " | Content [" + toXML() + "]";
+	}
+}