Smack provides a flexible framework for processing incoming packets using two constructs:
org.jivesoftware.smack.PacketCollector-- a class that lets you synchronously wait for new packets.org.jivesoftware.smack.PacketListener-- an interface for asynchronously notifying you of incoming packets. A packet listener is used for event style programming, while a packet collector has a result queue of packets that you can do polling and blocking operations on. So, a packet listener is useful when you want to take some action whenever a packet happens to come in, while a packet collector is useful when you want to wait for a specific packet to arrive. Packet collectors and listeners can be created using anXMPPConnectioninstance.
The org.jivesoftware.smack.filter.StanzaFilter interface determines which
specific packets will be delivered to a PacketCollector or PacketListener.
Many pre-defined filters can be found in the org.jivesoftware.smack.filter
package.
The following code snippet demonstrates registering both a packet collector and a packet listener:
// Create a packet filter to listen for new messages from a particular
// user. We use an AndFilter to combine two other filters._
StanzaFilter filter = new AndFilter(new StanzaTypeFilter(Message.class),
new FromContainsFilter("[email protected]"));
// Assume we've created an XMPPConnection name "connection".
// First, register a packet collector using the filter we created.
PacketCollector myCollector = connection.createPacketCollector(filter);
// Normally, you'd do something with the collector, like wait for new packets.
// Next, create a packet listener. We use an anonymous inner class for brevity.
PacketListener myListener = new PacketListener() {
**public** **void** processPacket(Packet packet) {
// Do something with the incoming packet here._
}
};
// Register the listener._
connection.addPacketListener(myListener, filter);
A rich set of packet filters are included with Smack, or you can create your
own filters by coding to the StanzaFilter interface. The default set of
filters includes:
StanzaTypeFilter-- filters for packets that are a particular Class type.StanzaIdFilter-- filters for packets with a particular packet ID.ThreadFilter-- filters for message packets with a particular thread ID.ToContainsFilter-- filters for packets that are sent to a particular address.FromContainsFilter-- filters for packets that are sent to a particular address.StanzaExtensionFilter-- filters for packets that have a particular packet extension.AndFilter-- implements the logical AND operation over two filters.OrFilter-- implements the logical OR operation over two filters.NotFilter-- implements the logical NOT operation on a filter.
Copyright (C) Jive Software 2002-2008