Mediator

Class Overview

Watches for Qualified bean implementations of T:

 // add @Named for automatic registration
 public class MyMediator
     implements Mediator<Named, MyType, MyWatcher>
 {
     public void add( BeanEntry<Named, MyType> entry, MyWatcher watcher )
         throws Exception
     {
         // translate event to whatever the watcher expects
     }
 
     public void remove( BeanEntry<Named, MyType> entry, MyWatcher watcher )
         throws Exception
     {
         // translate event to whatever the watcher expects
     }
 }
 

Mediator implementations must have a public no-arg constructor; they are neither injected nor injectable, acting instead as stateless translators.

IMPORTANT: mediation occurs when bindings change and there is at least one live watcher. If no-one requests or injects an instance of the watcher type then the mediator will not be called.

In the following example as soon as MyTabbedPane is injected, Sisu will use the SwingTabMediator to deliver all known JPanels annotated with @Tab to the watching MyTabbedPane. Sisu will continue to send updates, which add or remove tabs as appropriate, until the MyTabbedPane instance becomes unreachable. MyTabbedPane doesn't need to know anything about Sisu APIs and vice-versa because SwingTabMediator takes care of the necessary translation.

 @Named
 public class MyTabbedPane
     extends JTabbedPane
 {
     // watcher
 }
 
 @Qualifier
 @Retention( RetentionPolicy.RUNTIME )
 public @interface Tab
 {
     String title();
 }
 
 @Tab( title = "Summary" )
 public class SummaryTab
     extends JPanel
 {
     // qualified bean
 }
 
 @Tab( title = "Notes" )
 public class NotesTab
     extends JPanel
 {
     // qualified bean
 }
 
 @Named
 public class SwingTabMediator
     implements Mediator<Tab, JPanel, MyTabbedPane>
 {
     public void add( BeanEntry<Tab, JPanel> entry, final MyTabbedPane watcher )
         throws Exception
     {
         final Tab tab = entry.getKey();
         final JPanel panel = entry.getValue();
 
         SwingUtilities.invokeLater( new Runnable()
         {
             public void run()
             {
                 watcher.addTab( tab.title(), panel );
             }
         } );
     }
 
     public void remove( BeanEntry<Tab, JPanel> entry, final MyTabbedPane watcher )
         throws Exception
     {
         final Tab tab = entry.getKey();
 
         SwingUtilities.invokeLater( new Runnable()
         {
             public void run()
             {
                 watcher.removeTabAt( watcher.indexOfTab( tab.title() ) );
             }
         } );
     }
 }
 

Summary

Public Methods
abstract void	add(BeanEntry<Q, T> entry, W watcher) Processes the added BeanEntry and sends the necessary updates to the watcher.
abstract void	remove(BeanEntry<Q, T> entry, W watcher) Processes the removed BeanEntry and sends the necessary updates to the watcher.