问题
In ZF3 you would normally attach your event listener for the MvcEvent's in your module's Module.php like so:
<?php
namespace MyModule;
class Module
{
public function onBootstrap(MvcEvent $event)
{
$eventManager = $event->getApplication()->getEventManager();
$eventManager->attach(MvcEvent::EVENT_DISPATCH, function(MvcEvent $event) {
// Do someting...
});
}
}
Now there are two typical situations where your Module.php can grow big:
- Your module has to handle multiple (or even all)
MvcEvent's and maybe even treat them in different ways. - Your module has to perform multiple actions on a single
MvcEvent.
What I'd like to be able to do is to specify a class name in my module.config.php along with one or multiple MvcEvent names to keep my Module.php nice and clean.
Is there a way to do this in Zend Framework 3?
回答1:
@Nukeface has a great example but it does not directly answer my specific question.
To answer my own question:
This is possible with the use of listeners. A listener can be configured in the configuration files but it cannot be mapped to an event directly from the configuration alone.
It is possible to check for a specific setting in the configuration and determine what classes to map to what events. Even MvcEvents can be mapped this way.
Here's how to set it up:
1. The listener
We want to listen to multiple MvcEvents with one simple class. Note the class it extends.
namespace Demo\Listener;
class MyListener extends EventClassMapListener
{
public function handleEvent(MvcEvent $event)
{
// Do something
\Zend\Debug\Debug::dump($event->getName());
}
}
2. The abstract listener class
The above class needs a bit more body but that can be provided by the abstract listener class:
namespace Demo\Listener;
abstract class EventClassMapListener implements ListenerAggregateInterface
{
private $configuration;
public function __construct(array $configuration)
{
$this->configuration = $configuration;
}
public function attach(EventManagerInterface $events, $priority = 1)
{
$sharedManager = $events->getSharedManager();
foreach ($this->configuration as $identifier => $settings) {
foreach ($settings as $event => $configPriority) {
$sharedManager->attach($identifier, $event, [$this, 'handleEvent'], $configPriority ?: $priority);
}
}
}
public function detach(EventManagerInterface $events)
{
// Do the opposite of attach
}
abstract public function handleEvent(MvcEvent $event);
}
3. The factory
Now we need a factory that we can reuse for all our classes that need to listen to multiple events:
namespace Demo\Factory\Listener;
class EventClassmapListenerFactory implements FactoryInterface
{
public function __invoke(ContainerInterface $container, $requestedName, array $options = null)
{
$globalConfiguration = $container->get('config');
$configuration = [];
if (array_key_exists('event_classmap', $globalConfiguration)
&& array_key_exists($requestedName, $globalConfiguration['event_classmap'])
) {
$configuration = $globalConfiguration['event_classmap'][$requestedName];
}
return new $requestedName($configuration);
}
}
4. Configuration
In your module.config.php:
'service_manager' => [
'factories' => [
Listener\MyListener::class => Factory\Listener\EventClassmapListenerFactory::class,
],
],
'listeners' => [
Listener\MyListener::class,
],
'event_classmap' => [
// Name of the class that needs to listen to events
Listener\MyListener::class => [
// Identifier
\Zend\Mvc\Application::class => [
// List of event names and priorities
MvcEvent::EVENT_BOOTSTRAP => 1,
],
// Another identifier
MyEventEmitterClass::class => [
MyEventEmitterClass::EVENT_ONE,
MyEventEmitterClass::EVENT_TWO,
MyEventEmitterClass::EVENT_THREE,
],
],
],
Conclusion:
Although it might not really refined, I really like this idea. It is now fairly easy to add another listener and make it listen to a list of events from one or more emitters.
My opinion after some research
A listener itself should state what it wants to listen to, to keep things strict. Putting that information in a configuration file might result in a more complicated situation when it is not needed.
回答2:
You need a few things for Listener classes:
- Events
- Listeners
- Handlers
- Factories
- Config
Now, 2 & 3 are usually in the same class as you would usually have a Listener class for a specific purpose. Such as "Listen for Rocket launch and steer Rocket to Mars".
As such, you would need to "create" these "events" to listen for somewhere. Such as a DemoEvents class!
namespace Demo\Event;
use Zend\EventManager\Event;
class DemoEvent extends Event
{
const THE_STRING_TO_LISTEN_FOR = 'rocket.ready.for.launch';
const ANOTHER_STRING_TO_LISTEN_FOR = 'rocket.steer.to.mars';
}
Now that we have "events", we need to "listen" for them. For that we need a Listener. Because I'm limiting this to 1 example, the Handler (function(-ality) to be executed when the "event" we're "listening" for is "heard") will be in the same class.
namespace Demo\Listener;
use Demo\Event\DemoEvent;
use Zend\EventManager\Event;
use Zend\EventManager\EventManagerInterface;
use Zend\EventManager\ListenerAggregateInterface;
class DemoListener implements ListenerAggregateInterface
{
/**
* @var array
*/
protected $listeners = [];
/**
* @param EventManagerInterface $events
*/
public function detach(EventManagerInterface $events)
{
foreach ($this->listeners as $index => $listener) {
if ($events->detach($listener)) {
unset($this->listeners[$index]);
}
}
}
/**
* @param EventManagerInterface $events
*/
public function attach(EventManagerInterface $events, $priority = 1)
{
$sharedManager = $events->getSharedManager();
$sharedManager->attach(Demo::class, DemoEvent::THE_STRING_TO_LISTEN_FOR, [$this, 'doSomethingOnTrigger'], -10000);
}
/**
* Apart from triggering specific Listener function and de-registering itself, it does nothing else. Add your own functionality
*
* @param Event $event
*/
public function doSomethingOnTrigger(Event $event)
{
// Gets passed along parameters from the ->trigger() function elsewhere
$params = $event->getParams();
$specificClass = $params[SpecificClass::class];
// Do something useful here
$specificClass->launchRocketIntoOrbit();
// Detach self to prevent running again
$specificClass->getEventManager()->getSharedManager()->clearListeners(get_class($specificClass), $event->getName());
// NOTE: USE THIS TRIGGER METHODOLOGY ELSEWHERE USING THE STRING FROM THE ATTACH() FUNCTION TO TRIGGER THIS FUNCTION
// Trigger events specific for the Entity/class (this "daisy-chains" events, allowing for follow-up functionality)
$specificClass->getEventManager()->trigger(
DemoEvent::ANOTHER_STRING_TO_LISTEN_FOR,
$specificClass ,
[get_class($specificClass) => $specificClass ] // Params getting passed along
);
}
}
Excellent. We now have a events, a listener and a handler. We just need a factory to create this class when needed.
namespace Demo\Factory;
use Demo\Listener;
use Interop\Container\ContainerInterface;
use Zend\ServiceManager\Factory\FactoryInterface;
class DemoListenerFactory implements FactoryInterface
{
/**
* @param ContainerInterface $container
* @param string $requestedName
* @param array|null $options
* @return object|DemoListener
* @throws \Psr\Container\ContainerExceptionInterface
* @throws \Psr\Container\NotFoundExceptionInterface
*/
public function __invoke(ContainerInterface $container, $requestedName, array $options = null)
{
// If you're implementation of the Listener has any requirements, load them here and add a constructor in the DemoListener class
return new DemoListener();
}
}
Lastly, we need some config. Obviously we need to register the Listener + Factory combination. Let's do that first.
namespace Demo;
use Demo\Listener\DemoListener;
use Demo\Listener\DemoListenerFactory;
'service_manager' => [
'factories' => [
DemoListener::class => DemoListenerFactory::class,
],
],
Now for a little known bit of config to make sure that the Listener gets registered as a Listener:
'listeners' => [
DemoListener::class
],
Yep, that's it.
Make sure to add both of these bits of config at the first level of config, they're siblings.
来源：https://stackoverflow.com/questions/49181751/how-to-attach-event-listener-via-configuration-instead-of-module-bootstrap