php设计模式 之观察者模式 与Laravel 的事件

观察者模式主要用于解耦

1 没有观察者模式

class order
{
    public  function addOrder()
    {
        // 发短信
        Message::update();
        //发邮件
        Email::update();
        //记日志
        Log::update();
    }
   
    
}
$order = new order();
$order->addOrder();

2 观察者模式

2.1 被观察者 order

//被观察者
interface Observable
{
    //添加观察者实例
    function add();
    //删除观察者实例
    function del();
    //通知观察者
    function notify();
}

//订单类继承被观察者接口
class order implements Observable
{
    private $instance = array();
    //添加观察者实例
    function add(observe $observe)
    {
        // TODO: Implement add() method.
        $key = array_search($observe,$this->instance);
        if ($key === false){
            $this->instance[] = $observe;
        }
    }
    //删除观察者实例
    function del(observe $observe)
    {
        // TODO: Implement del() method.
        $key = array_search($observe,$this->instance);
        if ($key !== false){
            unset($this->instance[$key]);
        }
    }
    //通知观察者实例
    function notify()
    {
        // TODO: Implement notify() method.
        foreach ($this->instance as $key => $val){
            //调用实例化对象的update方法
            $val->update();
        }
    }
}

2.2 观察者 Email 、Message

/**
 * Interface observe
 * 定义一个观察者
 */
interface observe()
{
   //每个实例化对象都有update方法
   function update();
}

class Email implements observe
{
    function update()
    {
        echo "订单修改了,发送邮件";
    }
}
class Message implements observe
{
    function update()
    {
        echo "订单修改了,发送短信";
    }
}

2.3 客户端调用

$order = new order();
$order->add(new Email());
$order->add(new Message());
$order->del(new Email());
$order->notify();

3 Laravel的事件机制

3.1 执行命令

php artisan make:event EventTest

php artisan make:listener EventTestListener

3.2 生成文件

appListenersEventTestListener.php

<?php

namespace AppListeners;

use IlluminateQueueInteractsWithQueue;
use IlluminateContractsQueueShouldQueue;

class EventTestListener
{
    /**
     * Create the event listener.
     *
     * @return void
     */
    public function __construct()
    {
        //
    }

    /**
     * Handle the event.
     *
     * @param  object  $event
     * @return void
     */
    public function handle($event)
    {
        //
        echo "我是监听者/观察者 EventTestListener ";
    }
}

appEventsEventTest.php

<?php

namespace AppEvents;

use IlluminateBroadcastingChannel;
use IlluminateQueueSerializesModels;
use IlluminateBroadcastingPrivateChannel;
use IlluminateBroadcastingPresenceChannel;
use IlluminateFoundationEventsDispatchable;
use IlluminateBroadcastingInteractsWithSockets;
use IlluminateContractsBroadcastingShouldBroadcast;

class EventTest
{
    use Dispatchable, InteractsWithSockets, SerializesModels;

    /**
     * Create a new event instance.
     *
     * @return void
     */
    public function __construct()
    {
        //
    }

    /**
     * Get the channels the event should broadcast on.
     *
     * @return IlluminateBroadcastingChannel|array
     */
    public function broadcastOn()
    {
        //return new PrivateChannel('channel-name');
    }
}

outesweb.php

use AppEventsEventTest;

Route::get('/', function () {
    event(new EventTest());
});