Eclipse4 简单的IEventBroker例子

EventBroker是E4平台力推的事件处理机制实现,到底这东西有什么好的，我们来看一个例子就知道了。
1、创建一个E4工程。
2、假设我们需要在E4平台启动后执行一些任务，那么增加StartupLifeCycleHandler类,并在plugin.xml添加“lifeCycleURI”属性就可以了。

<extension id="product" point="org.eclipse.core.runtime.products">  
  <product name="client" application="org.eclipse.e4.ui.workbench.swt.E4Application">
    <property name="appName" value="client"></property>
    <property name="lifeCycleURI" value="platform:/plugin/client/client.handlers.StartupLifeCycleHandler"></property>
  </product>
</extension>

3、在StartupLifeCycleHandler定义事件处理机制

   package e4demo.handlers;import javax.inject.Inject;
   import org.eclipse.e4.core.contexts.IEclipseContext;
   import org.eclipse.e4.core.services.events.IEventBroker;
   import org.eclipse.e4.ui.internal.workbench.E4Workbench;
   import org.eclipse.e4.ui.workbench.lifecycle.PostContextCreate;
   import org.eclipse.jface.window.Window;
   import org.osgi.service.event.Event;
   import org.osgi.service.event.EventHandler;
   @SuppressWarnings("restriction")
   public class StartupLifeCycleHandler {
     @Inject
     IEventBroker eventBroker;
     @PostContextCreate
     public void startup(IEclipseContext context) {
       EventHandler attListener = new EventHandler() {
         @Override
         public void handleEvent(Event event) {
           System.out.println("event.getTopic: " + event.getTopic());
         }
       };
       if(eventBroker != null) {
         eventBroker.subscribe("hello", attListener);
       }
     }
   } 

然后通过eventBroker订阅了主题为“hello”的事件(和RSS订阅类似嘛),然后委托EventHandler处理。attListener的工作是接收到事件后将事件主题打印到控制台上。
4、在OpenHandler.java中发布”hello”事件主题

   import javax.inject.Inject;
   import org.eclipse.e4.core.di.annotations.Execute;
   import org.eclipse.e4.core.services.events.IEventBroker;
   public class OpenHandler {
     @Execute
     public void execute(IEventBroker eventBroker) throws Exception {
       eventBroker.send("hello", null);
     }
   }

5、运行,点击Open按钮，你会发现控制台输出：

   event.getTopic: hello