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Java > Open Source Codes > org > sapia > ubik > rmi > interceptor > Interceptor


1 package org.sapia.ubik.rmi.interceptor;
2
3
4 /**
5  * This interface is a marker that interceptor objects must implement.
6  * Interceptor classes are expected to defined methods that correspond
7  * to the event types (or classes) they expect. Events are objects that
8  * encapsulate state and are handled to the call back interceptor methods.
9  * <p>
10  * For example, suppose we define a given "event", through the
11  * <code>LogEvent</code> class (note that the "event" string does not need to
12  * appear in the class name). To intercept instances of this event, an
13  * interceptor needs to be implemented, which will have the following
14  * method:
15  * <p>
16  * <code>public void onLogEvent(LogEvent evt);</code>
17  * <p>
18  * As shown below, the method's signature must have the following pattern:
19  * <p>
20  * <code>on</code><i>EventClassName</i>(<i>EventClass</i>)
21  * <p>
22  * Once an interceptor class has been designed, it can be registered
23  * with a dispatcher to intercept events of the specified class:
24  * <p>
25  * <pre>
26  * SingleDispatcher disp = new SingleDispatcher();
27  * LogInterceptor it = new LogInterceptor();
28  * disp.registerInterceptor(LogEvent.class, it);
29  *
30  * // the following event will be intercepted by our interceptor.
31  * disp.dispatch(new LogEvent());
32  * </pre>
33  * <p>
34  * As one might have guessed, Java's introspection capabilities are
35  * used to match the event class to the proper interceptor method at
36  * registration time. This one-event-per-method scheme allows one interceptor
37  * to register for multiple event types.
38  * <p>
39  * Dispatching behavior and event registration policies can vary from
40  * one dispatcher to another.
41  *
42  * @author Yanick Duchesne
43  * <dl>
44  * <dt><b>Copyright:</b><dd>Copyright &#169; 2002-2003 <a HREF="http://www.sapia-oss.org">Sapia Open Source Software</a>. All Rights Reserved.</dd></dt>
45  * <dt><b>License:</b><dd>Read the license.txt file of the jar or visit the
46  * <a HREF="http://www.sapia-oss.org/license.html">license page</a> at the Sapia OSS web site</dd></dt>
47  * </dl>
48  */
49 public interface Interceptor {
50 }
51
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