Added new abstract event handler class to make development of new event handler easier. Added exception simulation to the MyEventHandler example event handler in the event.test project.

event.test/src/event/test/Activator.java

@@ -1,3 +1,16 @@
+/******************************************************************************
+ * Product: Adempiere ERP & CRM Smart Business Solution                       *
+ * Copyright (C) 2010 Heng Sin Low                							  *
+ * This program is free software; you can redistribute it and/or modify it    *
+ * under the terms version 2 of the GNU General Public License as published   *
+ * by the Free Software Foundation. This program is distributed in the hope   *
+ * that it will be useful, but WITHOUT ANY WARRANTY; without even the implied *
+ * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.           *
+ * See the GNU General Public License for more details.                       *
+ * You should have received a copy of the GNU General Public License along    *
+ * with this program; if not, write to the Free Software Foundation, Inc.,    *
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.                     *
+ *****************************************************************************/
 package event.test;
 
 import org.osgi.framework.BundleActivator;

event.test/src/event/test/MyEventHandler.java

@@ -1,36 +1,60 @@
+/******************************************************************************
+ * Product: Adempiere ERP & CRM Smart Business Solution                       *
+ * Copyright (C) 2010 Heng Sin Low                							  *
+ * This program is free software; you can redistribute it and/or modify it    *
+ * under the terms version 2 of the GNU General Public License as published   *
+ * by the Free Software Foundation. This program is distributed in the hope   *
+ * that it will be useful, but WITHOUT ANY WARRANTY; without even the implied *
+ * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.           *
+ * See the GNU General Public License for more details.                       *
+ * You should have received a copy of the GNU General Public License along    *
+ * with this program; if not, write to the Free Software Foundation, Inc.,    *
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.                     *
+ *****************************************************************************/
 package event.test;
 
+import org.adempiere.base.event.AbstractEventHandler;
 import org.adempiere.base.event.IEventManager;
 import org.adempiere.base.event.IEventTopics;
 import org.adempiere.base.event.LoginEventData;
+import org.compiere.model.I_C_BP_Group;
+import org.compiere.model.I_C_Order;
+import org.compiere.model.I_M_Product_Category;
 import org.compiere.model.PO;
 import org.osgi.service.event.Event;
-import org.osgi.service.event.EventHandler;
 
 /**
  *
  * @author hengsin
  *
  */
-public class MyEventHandler implements EventHandler {
+public class MyEventHandler extends AbstractEventHandler {
 
 	@Override
-	public void handleEvent(Event event) {
+	protected void doHandleEvent(Event event) {
 		if (event.getTopic().equals(IEventTopics.AFTER_LOGIN)) {
-			LoginEventData eventData = (LoginEventData) event.getProperty(IEventManager.EVENT_DATA);
+			LoginEventData eventData = getEventData(event);
 			System.out.println(" topic="+event.getTopic()+" AD_Client_ID="+eventData.getAD_Client_ID()
 					+" AD_Org_ID="+eventData.getAD_Org_ID()+" AD_Role_ID="+eventData.getAD_Role_ID()
 					+" AD_User_ID="+eventData.getAD_User_ID());
 		} else if (event.getTopic().equals(IEventTopics.PO_AFTER_NEW)) {
-			PO po = (PO) event.getProperty(IEventManager.EVENT_DATA);
+			PO po = getPO(event);
 			System.out.println(" topic="+event.getTopic()+" po="+po);
+		} else if (event.getTopic().equals(IEventTopics.PO_BEFORE_NEW)) {
+			PO po = getPO(event);
+			System.out.println(" topic="+event.getTopic()+" po="+po);
+			if (po.get_TableName().equals(I_C_BP_Group.Table_Name))
+				throw new RuntimeException("No new business partner group for now.");
 		}
 
 	}
 
-	public void bindEventManager(IEventManager eventManager) {
-		eventManager.register(IEventTopics.AFTER_LOGIN, this);
-		eventManager.register(IEventTopics.PO_AFTER_NEW, "(tableName=C_Order)", this);
+	@Override
+	protected void initialize() {
+		registerEvent(IEventTopics.AFTER_LOGIN);
+		registerTableEvent(IEventTopics.PO_AFTER_NEW, I_C_Order.Table_Name);
+		registerTableEvent(IEventTopics.PO_BEFORE_NEW, I_C_BP_Group.Table_Name);
+		registerTableEvent(IEventTopics.PO_BEFORE_NEW, I_M_Product_Category.Table_Name);
 	}
 
 	public void unbindEventManager(IEventManager eventManager) {

org.adempiere.base/src/org/adempiere/base/event/AbstractEventHandler.java

@@ -0,0 +1,153 @@
+/******************************************************************************
+ * Product: Adempiere ERP & CRM Smart Business Solution                       *
+ * Copyright (C) 2010 Heng Sin Low                							  *
+ * This program is free software; you can redistribute it and/or modify it    *
+ * under the terms version 2 of the GNU General Public License as published   *
+ * by the Free Software Foundation. This program is distributed in the hope   *
+ * that it will be useful, but WITHOUT ANY WARRANTY; without even the implied *
+ * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.           *
+ * See the GNU General Public License for more details.                       *
+ * You should have received a copy of the GNU General Public License along    *
+ * with this program; if not, write to the Free Software Foundation, Inc.,    *
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.                     *
+ *****************************************************************************/
+package org.adempiere.base.event;
+
+import java.util.List;
+
+import org.compiere.model.PO;
+import org.osgi.service.event.Event;
+import org.osgi.service.event.EventHandler;
+
+/**
+ * @author hengsin
+ *
+ */
+public abstract class AbstractEventHandler implements EventHandler {
+
+	protected IEventManager eventManager = null;
+
+	/**
+	 * @see org.osgi.service.event.EventHandler#handleEvent(org.osgi.service.event.Event)
+	 */
+	@Override
+	public void handleEvent(Event event) {
+		try {
+			doHandleEvent(event);
+		} catch (RuntimeException e) {
+			addError(event, e);
+			throw e;
+		} catch (Exception e) {
+			addError(event, e);
+			throw new RuntimeException(e);
+		} catch (Error e) {
+			addError(event, e);
+			throw e;
+		} catch (Throwable e) {
+			addError(event, e);
+			throw new Error(e);
+		}
+	}
+
+	/**
+	 * @param eventManager
+	 */
+	public void bindEventManager(IEventManager eventManager) {
+		this.eventManager = eventManager;
+		initialize();
+	}
+
+	/**
+	 * @param eventManager
+	 */
+	public void unbindEventManager(IEventManager eventManager) {
+		this.eventManager = null;
+		eventManager.unregister(this);
+	}
+
+	/**
+	 * override this method to handle event
+	 * @param event
+	 */
+	protected abstract void doHandleEvent(Event event);
+
+	/**
+	 * override this method to register event that the class want to listen to
+	 */
+	protected abstract void initialize();
+
+	/**
+	 *
+	 * @param eventTopic
+	 */
+	protected void registerEvent(String eventTopic) {
+		this.registerEvent(eventTopic, null);
+	}
+
+	/**
+	 *
+	 * @param topic
+	 * @param filter
+	 */
+	protected void registerEvent(String topic, String filter) {
+		if (filter != null)
+			eventManager.register(topic, filter, this);
+		else
+			eventManager.register(topic, this);
+	}
+
+	/**
+	 * @param topic
+	 * @param tableName
+	 */
+	protected void registerTableEvent(String topic, String tableName) {
+		String filter = "(tableName="+tableName+")";
+		registerEvent(topic, filter);
+	}
+
+	/**
+	 * @param event
+	 * @return PO
+	 */
+	protected PO getPO(Event event) {
+		return getEventProperty(event, IEventManager.EVENT_DATA);
+	}
+
+	/**
+	 *
+	 * @param <T>
+	 * @param event
+	 */
+	protected <T> T getEventData(Event event) {
+		return getEventProperty(event, IEventManager.EVENT_DATA);
+	}
+
+	/**
+	 *
+	 * @param <T>
+	 * @param event
+	 * @param property
+	 */
+	@SuppressWarnings("unchecked")
+	protected <T> T getEventProperty(Event event, String property) {
+		return (T) event.getProperty(property);
+	}
+
+	/**
+	 * @param event
+	 * @param e
+	 */
+	protected void addError(Event event, Throwable e) {
+		addErrorMessage(event, e.getLocalizedMessage());
+	}
+
+	/**
+	 * @param event
+	 * @param errorMessage
+	 */
+	protected void addErrorMessage(Event event, String errorMessage) {
+		List<String> errors = getEventProperty(event, IEventManager.EVENT_ERROR_MESSAGES);
+		if (errors != null)
+			errors.add(errorMessage);
+	}
+}