* * By default, Smack only knows how to process IQ packets with query sub-packets that * are in a few namespaces:
* <?xml version="1.0"?> * <smackProviders> * <iqProvider> * <elementName>query</elementName> * <namespace>jabber:iq:time</namespace> * <className>org.jivesoftware.smack.packet.Time</className> * </iqProvider> * </smackProviders>* * Each IQ provider is associated with an element name and a namespace. If multiple provider entries attempt to * register to handle the same namespace, the first entry loaded from the classpath will * take precedence. The IQ provider class can either implement the IQProvider interface, * or extend the IQ class. In the former case, each IQProvider is responsible for parsing * the raw XML stream to create an IQ instance. In the latter case, bean introspection is * used to try to automatically set properties of the IQ instance using the values found * in the IQ packet XML. For example, an XMPP time packet resembles the following: *
* <iq type='result' to='joe@example.com' from='mary@example.com' id='time_1'> * <query xmlns='jabber:iq:time'> * <utc>20020910T17:58:35</utc> * <tz>MDT</tz> * <display>Tue Sep 10 12:58:35 2002</display> * </query> * </iq>* * In order for this packet to be automatically mapped to the Time object listed in the * providers file above, it must have the methods setUtc(String), setTz(String), and * setDisplay(tz). The introspection service will automatically try to convert the String * value from the XML into a boolean, int, long, float, double, or Class depending on the * type the IQ instance expects.
* * A pluggable system for the <x> portion of packets also exists. Each x provider * is registered with a name space in the smack.providers file as in the following example: * *
* <?xml version="1.0"?> * <smackProviders> * <xProvider namespace="jabber:iq:event" * className="org.jivesoftware.smack.packet.MessageEvent"/> * </smackProviders>* * If multiple provider entries attempt to register to handle the same namespace, the * first entry loaded from the classpath will take precedence. Whenever an <x> element * is found in a packet, parsing will be passed to the correct provider. Each provider * can either implement the XProvider or be a standard Java Bean. In the former case, * each XProvider is responsible for parsing the raw XML stream to contruct an object. * In the latter case, bean introspection is used to try to automatically set the * properties of the class using the values in the x sub-element. When a XProvider is * not registered for a namespace, Smack will store all top-level elements of the sub-packet * in a Map and attach it to the packet. * * @author Matt Tucker */ public class ProviderManager { private static Map extensionProviders = new Hashtable(); private static Map iqProviders = new Hashtable(); static { // Load IQ processing providers. try { Enumeration enum = ProviderManager.class.getClassLoader().getResources( "WEB-INF/smack.providers"); while (enum.hasMoreElements()) { URL url = (URL)enum.nextElement(); java.io.InputStream providerStream = null; try { providerStream = url.openStream(); XmlPullParser parser = getParserInstance(); parser.setInput(providerStream, "UTF-8"); int eventType = parser.getEventType(); do { if (eventType == XmlPullParser.START_TAG) { if (parser.getName().equals("iqProvider")) { parser.next(); parser.next(); String elementName = parser.nextText(); parser.next(); parser.next(); String namespace = parser.nextText(); parser.next(); parser.next(); String className = parser.nextText(); // Only add the provider for the namespace if one isn't // already registered. String key = getProviderKey(elementName, namespace); if (!iqProviders.containsKey(key)) { // Attempt to load the provider class and then create // a new instance if it's an IQProvider. Otherwise, if it's // an IQ class, add the class object itself, then we'll use // reflection later to create instances of the class. try { // Add the provider to the map. Class provider = Class.forName(className); if (IQProvider.class.isAssignableFrom(provider)) { iqProviders.put(key, provider.newInstance()); } else if (IQ.class.isAssignableFrom(provider)) { iqProviders.put(key, provider); } } catch (ClassNotFoundException cnfe) { cnfe.printStackTrace(); } } } else if (parser.getName().equals("extensionProvider")) { parser.next(); parser.next(); String elementName = parser.nextText(); parser.next(); parser.next(); String namespace = parser.nextText(); parser.next(); parser.next(); String className = parser.nextText(); // Only add the provider for the namespace if one isn't // already registered. String key = getProviderKey(elementName, namespace); if (!extensionProviders.containsKey(key)) { // Attempt to load the provider class and then create // a new instance if it's a Provider. Otherwise, if it's // a PacketExtension, add the class object itself and // then we'll use reflection later to create instances // of the class. try { // Add the provider to the map. Class provider = Class.forName(className); if (PacketExtensionProvider.class.isAssignableFrom(provider)) { extensionProviders.put(key, provider.newInstance()); } else if (PacketExtension.class.isAssignableFrom(provider)) { extensionProviders.put(key, provider); } } catch (ClassNotFoundException cnfe) { cnfe.printStackTrace(); } } } } eventType = parser.next(); } while (eventType != XmlPullParser.END_DOCUMENT); } finally { try { providerStream.close(); } catch (Exception e) { } } } } catch (Exception e) { } } /** * Returns the IQ provider registered to the specified XML element name and namespace. * For example, if a provider was registered to the element name "query" and the * namespace "jabber:iq:time", then the following packet would trigger the provider: * *
* <iq type='result' to='joe@example.com' from='mary@example.com' id='time_1'>
* <query xmlns='jabber:iq:time'>
* <utc>20020910T17:58:35</utc>
* <tz>MDT</tz>
* <display>Tue Sep 10 12:58:35 2002</display>
* </query>
* </iq>
*
* @param elementName the XML element name.
* @param namespace the XML namespace.
* @return
*/
public synchronized static Object getIQProvider(String elementName, String namespace) {
String key = getProviderKey(elementName, namespace);
return iqProviders.get(key);
}
/**
* Returns the packet extension provider registered to the specified XML element name
* and namespace. For example, if a provider was registered to the element name "x" and the
* namespace "jabber:x:event", then the following packet would trigger the provider:
*
*
* <message to='romeo@montague.net' id='message_1'>
* <body>Art thou not Romeo, and a Montague?</body>
* <x xmlns='jabber:x:event'>
* <composing/>
* </x>
* </message>
*
* @param elementName
* @param namespace
* @return
*/
public synchronized static Object getExtensionProvider(String elementName, String namespace) {
String key = getProviderKey(elementName, namespace);
return extensionProviders.get(key);
}
/**
* Returns a String key for a given element name and namespace.
*
* @param elementName the element name.
* @param namespace the namespace.
* @return a unique key for the element name and namespace pair.
*/
private static String getProviderKey(String elementName, String namespace) {
StringBuffer buf = new StringBuffer();
buf.append("<").append(elementName).append("/><").append(namespace).append("/>");
return buf.toString();
}
/**
* Returns an XML parser instance.
*
* @return an XML parser instance.
*/
private static XmlPullParser getParserInstance() {
XmlPullParser parser = null;
try {
final String defaultProviderName = "org.xmlpull.mxp1.MXParserFactory";
XmlPullParserFactory factory = null;
try {
// Attempt to load a factory implementation using a system property
// and a classloader context.
factory = XmlPullParserFactory.newInstance(
System.getProperty(XmlPullParserFactory.PROPERTY_NAME),
Thread.currentThread().getContextClassLoader().getClass());
}
catch (Exception e) {
if (factory == null) {
// Loading failed. Therefore, use the hardcoded default.
factory = XmlPullParserFactory.newInstance(defaultProviderName, null);
}
}
factory.setNamespaceAware(true);
parser = factory.newPullParser();
}
catch (XmlPullParserException xppe) {
xppe.printStackTrace();
}
return parser;
}
}