Yet Another Apex Trigger Template

TaskAfterInsertHandler.java

/**
 After insert handler on task Sobject
*/
public class TaskAfterInsertHandler implements Triggers.Handler {
	public void handle() {
		System.debug(LoggingLevel.INFO, 'Post insert handling ' + Trigger.new );
	}
}

TaskAfterUpdateHandler.java

/**
 After update handler on Task Sobject
*/
public class TaskAfterUpdateHandler implements Triggers.Handler {
        // Prevent trigger from running twice on updates
        // Ref : http://raydehler.com/cloud/clod/prevent-an-apex-trigger-from-executing-twice.html
	static boolean firstRunForUpdate = true;
	public void handle() {
		if (firstRunForUpdate) {
		   System.debug(LoggingLevel.INFO, 'Post Update handling, NewItems: ' + Trigger.newMap + ', OldItems: ' + Trigger.oldMap );
		}
		
	}
}

TaskBeforeInsertHandler.java

/**
 Before insert handler on task Sobject
*/
public class TaskBeforeInsertHandler implements Triggers.Handler {
	public void handle() {
		System.debug(LoggingLevel.INFO, 'Pre insert handling ' + Trigger.new );
	}
} 

TaskBeforeInsertHandler2.java

/**
 Before insert handler on task Sobject. This is SECOND before insert handler on the same Task Sobject
*/
public class TaskBeforeInsertHandler2 implements Triggers.Handler {
	public void handle() {
		System.debug(LoggingLevel.INFO, '2. Pre insert handling ' + Trigger.new );
	}
} 

TaskTrigger.java

/**
 Trigger on Task Sobject
*/
trigger TaskTrigger on Task (after delete, after insert, after undelete, 
					 		 after update, before delete, 
							 before insert, before update) {
	

	new Triggers()
		.bind(Triggers.Evt.afterinsert,  new TaskAfterInsertHandler())
		// bind first before insert handler
		.bind(Triggers.Evt.beforeinsert, new TaskBeforeInsertHandler())
		// bind another before insert handler, that will execute after the first one.
		// All you need to do is add handlers in the correct order here 
		.bind(Triggers.Evt.beforeinsert, new TaskBeforeInsertHandler2())
		.bind(Triggers.Evt.afterupdate, new TaskAfterUpdateHandler())
		// Done with adding all handlers, lets call the manage now for once only
		.manage();

}

Triggers.java

public class Triggers {
	/**
		Enum representing each of before/after CRUD events on Sobjects
	*/
	public enum Evt {
		afterdelete, afterinsert, afterundelete,
		afterupdate, beforedelete, beforeinsert, beforeupdate	
	}
	
	/**
		Simplistic handler to implement on any of the event. It doesn't requires or enforces any patter except the
		method name to be "handle()", a developer is free to use any Trigger context variable or reuse any other
		apex class here.
	*/
	public interface Handler {
		void handle();			
	} 
	
	// Internal mapping of handlers
	Map<String, List<Handler>> eventHandlerMapping = new Map<String, List<Handler>>();
	
	/**
		Core API to bind handlers with events
	*/
	public Triggers bind(Evt event, Handler eh) {
		List<Handler> handlers = eventHandlerMapping.get(event.name());
		if (handlers == null) {
			handlers = new List<Handler>();
			eventHandlerMapping.put(event.name(), handlers);
		}
		handlers.add(eh);
		return this;
	}
	
	/**
		Invokes correct handlers as per the context of trigger and available registered handlers
	*/
	public void manage() {
		Evt ev = null;
		if(Trigger.isInsert && Trigger.isBefore){
			ev = Evt.beforeinsert;
		} else if(Trigger.isInsert && Trigger.isAfter){
			ev = Evt.afterinsert;
		} else if(Trigger.isUpdate && Trigger.isBefore){
			ev = Evt.beforeupdate;
		} else if(Trigger.isUpdate && Trigger.isAfter){
			ev = Evt.afterupdate;
		} else if(Trigger.isDelete && Trigger.isBefore){
			ev = Evt.beforedelete;
		} else if(Trigger.isDelete && Trigger.isAfter){
			ev = Evt.afterdelete;
		} else if(Trigger.isundelete){
			ev = Evt.afterundelete;				
		}
		List<Handler> handlers = eventHandlerMapping.get(ev.name());
		if (handlers != null && !handlers.isEmpty()) {
			for (Handler h : handlers) {
				h.handle();
			}
		}
	}
	
}