61 lines
3.0 KiB
Markdown
61 lines
3.0 KiB
Markdown
Processing Incoming Stanzas
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===========================
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[Back](index.md)
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Smack provides a flexible framework for processing incoming stanzas using two
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constructs:
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* `org.jivesoftware.smack.StanzaCollector` -- a class that lets you synchronously wait for new stanzas.
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* `org.jivesoftware.smack.StanzaListener` -- an interface for asynchronously notifying you of incoming stanzas. A stanza listener is used for event style programming, while a stanza collector has a result queue of stanzas that you can do polling and blocking operations on. So, a stanza listener is useful when you want to take some action whenever a stanza happens to come in, while a stanza collector is useful when you want to wait for a specific stanza to arrive. Stanza collectors and listeners can be created using an `XMPPConnection` instance.
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The `org.jivesoftware.smack.filter.StanzaFilter` interface determines which
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specific stanzas will be delivered to a `StanzaCollector` or `StanzaListener`.
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Many pre-defined filters can be found in the `org.jivesoftware.smack.filter`
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package.
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The following code snippet demonstrates registering both a stanza collector
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and a stanza listener:
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```
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// Create a stanza filter to listen for new messages from a particular
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// user. We use an AndFilter to combine two other filters._
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StanzaFilter filter = new AndFilter(StanzaTypeFilter.MESSAGE,
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FromMatchesFilter.create(JidCreate.entityBareFrom("mary@jivesoftware.com")));
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// Assume we've created an XMPPConnection named "connection".
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// First, register a stanza collector using the filter we created.
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StanzaCollector myCollector = connection.createStanzaCollector(filter);
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// Normally, you'd do something with the collector, like wait for new packets.
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// Next, create a stanza listener. We use an anonymous inner class for brevity.
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StanzaListener myListener = new StanzaListener() {
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public void processStanza(Stanza stanza) {
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// Do something with the incoming stanza here._
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}
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};
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// Register the listener._
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connection.addAsyncStanzaListener(myListener, filter);
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// or for a synchronous stanza listener use
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connection.addSyncStanzaListener(myListener, filter);
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```
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Standard Stanza Filters
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-----------------------
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A rich set of stanza filters are included with Smack, or you can create your
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own filters by coding to the `StanzaFilter` interface. The default set of
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filters includes:
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* `StanzaTypeFilter` -- filters for stanzas that are a particular Class type.
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* `StanzaIdFilter` -- filters for stanzas with a particular packet ID.
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* `ThreadFilter` -- filters for message stanzas with a particular thread ID.
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* `ToMatchesFilter` -- filters for stanzas that are sent to a particular address.
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* `FromMatchesFilter` -- filters for stanzas that are sent from a particular address.
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* `StanzaExtensionFilter` -- filters for stanzas that have a particular stanza extension.
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* `AndFilter` -- implements the logical AND operation over two filters.
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* `OrFilter` -- implements the logical OR operation over two filters.
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* `NotFilter` -- implements the logical NOT operation on a filter.
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Copyright (C) Jive Software 2002-2008
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