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      1 /**
      2  * All rights reserved. Licensed under the Apache License, Version 2.0 (the "License");
      3  * you may not use this file except in compliance with the License.
      4  * You may obtain a copy of the License at
      5  *
      6  *     http://www.apache.org/licenses/LICENSE-2.0
      7  *
      8  * Unless required by applicable law or agreed to in writing, software
      9  * distributed under the License is distributed on an "AS IS" BASIS,
     10  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     11  * See the License for the specific language governing permissions and
     12  * limitations under the License.
     13  */
     14 package org.jivesoftware.smackx.pubsub;
     15 
     16 import org.jivesoftware.smack.packet.Message;
     17 import org.jivesoftware.smack.packet.PacketExtension;
     18 import org.jivesoftware.smackx.pubsub.provider.ItemProvider;
     19 
     20 /**
     21  * This class represents an item that has been, or will be published to a
     22  * pubsub node.  An <tt>Item</tt> has several properties that are dependent
     23  * on the configuration of the node to which it has been or will be published.
     24  *
     25  * <h1>An Item received from a node (via {@link LeafNode#getItems()} or {@link LeafNode#addItemEventListener(org.jivesoftware.smackx.pubsub.listener.ItemEventListener)}</b>
     26  * <li>Will always have an id (either user or server generated) unless node configuration has both
     27  * {@link ConfigureForm#isPersistItems()} and {@link ConfigureForm#isDeliverPayloads()}set to false.
     28  * <li>Will have a payload if the node configuration has {@link ConfigureForm#isDeliverPayloads()} set
     29  * to true, otherwise it will be null.
     30  *
     31  * <h1>An Item created to send to a node (via {@link LeafNode#send()} or {@link LeafNode#publish()}</b>
     32  * <li>The id is optional, since the server will generate one if necessary, but should be used if it is
     33  * meaningful in the context of the node.  This value must be unique within the node that it is sent to, since
     34  * resending an item with the same id will overwrite the one that already exists if the items are persisted.
     35  * <li>Will require payload if the node configuration has {@link ConfigureForm#isDeliverPayloads()} set
     36  * to true.
     37  *
     38  * <p>To customise the payload object being returned from the {@link #getPayload()} method, you can
     39  * add a custom parser as explained in {@link ItemProvider}.
     40  *
     41  * @author Robin Collier
     42  */
     43 public class PayloadItem<E extends PacketExtension> extends Item
     44 {
     45 	private E payload;
     46 
     47 	/**
     48 	 * Create an <tt>Item</tt> with no id and a payload  The id will be set by the server.
     49 	 *
     50 	 * @param payloadExt A {@link PacketExtension} which represents the payload data.
     51 	 */
     52 	public PayloadItem(E payloadExt)
     53 	{
     54 		super();
     55 
     56 		if (payloadExt == null)
     57 			throw new IllegalArgumentException("payload cannot be 'null'");
     58 		payload = payloadExt;
     59 	}
     60 
     61 	/**
     62 	 * Create an <tt>Item</tt> with an id and payload.
     63 	 *
     64 	 * @param itemId The id of this item.  It can be null if we want the server to set the id.
     65 	 * @param payloadExt A {@link PacketExtension} which represents the payload data.
     66 	 */
     67 	public PayloadItem(String itemId, E payloadExt)
     68 	{
     69 		super(itemId);
     70 
     71 		if (payloadExt == null)
     72 			throw new IllegalArgumentException("payload cannot be 'null'");
     73 		payload = payloadExt;
     74 	}
     75 
     76 	/**
     77 	 * Create an <tt>Item</tt> with an id, node id and payload.
     78 	 *
     79 	 * <p>
     80 	 * <b>Note:</b> This is not valid for publishing an item to a node, only receiving from
     81 	 * one as part of {@link Message}.  If used to create an Item to publish
     82 	 * (via {@link LeafNode#publish(Item)}, the server <i>may</i> return an
     83 	 * error for an invalid packet.
     84 	 *
     85 	 * @param itemId The id of this item.
     86 	 * @param nodeId The id of the node the item was published to.
     87 	 * @param payloadExt A {@link PacketExtension} which represents the payload data.
     88 	 */
     89 	public PayloadItem(String itemId, String nodeId, E payloadExt)
     90 	{
     91 		super(itemId, nodeId);
     92 
     93 		if (payloadExt == null)
     94 			throw new IllegalArgumentException("payload cannot be 'null'");
     95 		payload = payloadExt;
     96 	}
     97 
     98 	/**
     99 	 * Get the payload associated with this <tt>Item</tt>.  Customising the payload
    100 	 * parsing from the server can be accomplished as described in {@link ItemProvider}.
    101 	 *
    102 	 * @return The payload as a {@link PacketExtension}.
    103 	 */
    104 	public E getPayload()
    105 	{
    106 		return payload;
    107 	}
    108 
    109 	@Override
    110 	public String toXML()
    111 	{
    112 		StringBuilder builder = new StringBuilder("<item");
    113 
    114 		if (getId() != null)
    115 		{
    116 			builder.append(" id='");
    117 			builder.append(getId());
    118 			builder.append("'");
    119 		}
    120 
    121         if (getNode() != null) {
    122             builder.append(" node='");
    123             builder.append(getNode());
    124             builder.append("'");
    125         }
    126 		builder.append(">");
    127 		builder.append(payload.toXML());
    128 		builder.append("</item>");
    129 
    130 		return builder.toString();
    131 	}
    132 
    133 	@Override
    134 	public String toString()
    135 	{
    136 		return getClass().getName() + " | Content [" + toXML() + "]";
    137 	}
    138 }
    139