ClientStateHelper


1   package org.oddjob.jmx.client;
2   
3   import java.util.ArrayList  ;
4   import java.util.Iterator  ;
5   import java.util.List  ;
6   
7   import org.oddjob.state.JobState;
8   import org.oddjob.state.JobStateEvent;
9   import org.oddjob.state.JobStateListener;
10  
11  /**
12   * Implement a remote state listener. This handles remote state events and also
13   * propogates them on the client side as normal state events.
14   * 
15   * @author Rob Gordon
16   */
17  
18  class ClientStateHelper {
19  
20      /** Remember the last event so new state listeners can be told it. */
21      private JobStateEvent lastEvent;
22  
23      /** State listeners */
24      private final List   listeners = new ArrayList  ();
25  
26      /** The owner, to be used as the source of the event. */
27      private final Object   owner;
28  
29      /**
30       * Constructor.
31       * 
32       * @param owner The owning (source) object.
33       */
34  
35      public ClientStateHelper(Object   owner) {        
36          this.owner = owner;
37          lastEvent = new JobStateEvent(owner, JobState.READY, null); 
38      }
39  
40      public void jobStateChange(JobStateEvent event) {
41          // The event that comes over the wire with the wrong source, so create a new one
42          // job node client proxy as the source.
43          JobStateEvent newEvent = new JobStateEvent(owner, event.getJobState(),
44                  event.getTime(), event.getException());
45  
46          lastEvent = newEvent;
47          List   copy = null;
48          synchronized (listeners) {
49              copy = new ArrayList  (listeners);
50          }
51          for (Iterator   it = copy.iterator(); it.hasNext();) {                
52              ((JobStateListener)it.next()).jobStateChange(newEvent); 
53          }
54      }
55      
56      /**
57       * Add a job state listener.
58       * 
59       * @param listener The job state listener.
60       */
61      public void addJobStateListener(JobStateListener listener) {    
62          synchronized (listeners) {
63              listeners.add(listener);
64              JobStateEvent nowEvent = null;
65              nowEvent = lastEvent;
66              
67              listener.jobStateChange(nowEvent);
68          }
69      }
70  
71      /**
72       * Remove a job state listener.
73       * 
74       * @param listener The job state listener.
75       */
76      public void removeJobStateListener(JobStateListener listener) {
77          synchronized (listeners) {
78              listeners.remove(listener);
79          }
80      }
81  
82  }
83
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