事件及事件監聽

事件 如文章瀏覽數,用戶關注等這些動做均可以稱做事件，經過事件監聽,而後對監聽事件執行(如更新瀏覽數,關注人數等)相應的操做

1.在 app/Providers/EventServiceProvider.php中註冊事件監聽器映射關係

protected $listen = [
   
    'App\Events\BlogView' => [  //事件
        'App\Listeners\BlogViewListener', //事件監聽
    ],
    // 'App\Events\SomeEvent' => [       可多個事件,事件監聽
    //     'App\Listeners\EventListener',
    // ],
];

2.執行命令 生成事件文件和事件監聽文件　

php artisan event:generate

 注：該命令完成後，會分別自動在 app/Events和app/Listensers目錄下生成 BlogView.php和BlogViewListener.php文件。

3.事件

<?php

namespace App\Events;

use App\Events\Event;
use App\Blog;//模型
use Illuminate\Queue\SerializesModels;
use Illuminate\Contracts\Broadcasting\ShouldBroadcast;

class BlogView extends Event
{
    use SerializesModels;

    /**
     * Create a new event instance.
     *
     * @return void
     */
    public function __construct(Blog $blog)
    {
        $this->blog = $blog;
    }

    /**
     * Get the channels the event should be broadcast on.
     *
     * @return array
     */
    public function broadcastOn()
    {
        return [];
    }
}

　注：僅構造函數中將模型當作實例傳入

4.事件監聽

<?php

namespace App\Listeners;

use App\Events\BlogView; //引入事件
use Illuminate\Queue\InteractsWithQueue;
use Illuminate\Contracts\Queue\ShouldQueue;
use Illuminate\Session\Store;

class BlogViewListener
{
    protected $session;
    /**
     * Create the event listener.
     *
     * @return void
     */
    public function __construct(Store $session)
    {
        $this->session = $session;
    }

    /**
     * Handle the event.
     *
     * @param  BlogView  $event
     * @return void
     */
    public function handle(BlogView $event)
    {
        $blog = $event->blog;
        //先進行判斷是否已經查看過
        if (!$this->hasViewedBlog($blog)) {
            //保存到數據庫
            $blog->view_cache = $blog->view_cache + 10;
            $blog->save();
            //看過以後將保存到 Session 
            $this->storeViewedBlog($blog);
        }
    }

    protected function hasViewedBlog($blog)
    {
        return array_key_exists($blog->id, $this->getViewedBlogs());
    }

    protected function getViewedBlogs()
    {
        return $this->session->get('viewed_Blogs', []);
    }

    protected function storeViewedBlog($blog)
    {
        $key = 'viewed_Blogs.'.$blog->id;
        $this->session->put($key, time());
    }

}

5.控制器中應用事件監聽

<?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;
use App\Blog;
use Illuminate\Support\Facades\Event;
use App\Http\Requests;
use App\Events\BlogView; //引入事件監聽
use App\Http\Controllers\Controller;

class BlogController extends Controller
{
   
    public function show()
    {
        $blog = Blog::where('id',1)->first(); //實例
        Event::fire(new BlogView($blog));
       
    }

}

6.相關的代碼

CREATE TABLE `blog` (
  `id` int(11) NOT NULL,
  `title` varchar(30) NOT NULL COMMENT '標題',
  `view_cache` smallint(6) NOT NULL COMMENT '訪問次數',
  `updated_at` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

路由

//事件，註冊，監聽
Route::get('blog/show','BlogController@show');