Laravel框架學習 -- php artisan down/up

    因爲某種緣由，公司總體框架由python的flask框架，轉換爲php的laravel。在斷斷續續幾個月的時間裏，邊繼續寫着flask框架，邊學着laravel。說下本身如今的狀態吧。前段時間差很少都在個1-2點睡覺，大概四月份有段時間居然到了3-4點才睡的地步。

    路漫漫其修遠兮，總感受時間不夠用的。大概是本身以前浪費的時間太多了，是時候還上了。

---

    laravel文檔中文版的，大概看到過三個。隨便找個看看就能夠了。http://laravel-china.org/docs/5.1 

# 輸入 php artisan 便可看到所有可用命令

  down                 Put the application into maintenance mode
  up                   Bring the application out of maintenance mode

    總體流程大致（由於詳細的我也不是很清楚╮(╯_╰)╭）說下吧。

1、命令的實現

    1. 做爲服務提供者，加載到程序中。

// config/app.php 中。
'providers' => [
    // 這個即是 laravel自帶的 artisan 命令提供者
    Illuminate\Foundation\Providers\ArtisanServiceProvider::class,
]

    2.而後找到 Up/Down 命令入口

/**
 * Register the command.
 *
 * @return void
 */
protected function registerUpCommand()
{
    $this->app->singleton('command.up', function () {
        return new UpCommand;
    });
}


/**
 * Register the command.
 *
 * @return void
 */
protected function registerDownCommand()
{
    $this->app->singleton('command.down', function () {
        return new DownCommand;
    });
}

    3.1 DownCommand實現

class DownCommand extends Command
{
    /**
     * The console command name.
     *
     * @var string
     */
    protected $name = 'down';

    /**
     * The console command description.
     *
     * @var string
     */
    protected $description = 'Put the application into maintenance mode';

    /**
     * Execute the console command.
     *
     * @return void
     */
    public function fire()
    {
        // 關鍵點： 在當前存儲目錄/framework 下面建立一個 down文件
        touch($this->laravel->storagePath().'/framework/down');

        $this->comment('Application is now in maintenance mode.');
    }
}


// touch() 函數php文檔解釋
/**
 * Sets access and modification time of file
 * @link http://php.net/manual/en/function.touch.php
 * @param string $filename <p>
 * The name of the file being touched.
 * </p>
 * @param int $time [optional] <p>
 * The touch time. If time is not supplied, 
 * the current system time is used.
 * </p>
 * @param int $atime [optional] <p>
 * If present, the access time of the given filename is set to 
 * the value of atime. Otherwise, it is set to
 * time.
 * </p>
 * @return bool true on success or false on failure.
 * @since 4.0
 * @since 5.0
 */
function touch ($filename, $time = null, $atime = null) {}

    3.2 UpCommand 實現

class UpCommand extends Command
{
    /**
     * The console command name.
     *
     * @var string
     */
    protected $name = 'up';

    /**
     * The console command description.
     *
     * @var string
     */
    protected $description = 'Bring the application out of maintenance mode';

    /**
     * Execute the console command.
     *
     * @return void
     */
    public function fire()
    {
        // 關鍵：刪除laravel存儲目錄/fromework 下面的 down 文件
        @unlink($this->laravel->storagePath().'/framework/down');

        $this->info('Application is now live.');
    }
}


// @unlink() php文檔解釋
/**
 * Deletes a file
 * @link http://php.net/manual/en/function.unlink.php
 * @param string $filename <p>
 * Path to the file.
 * </p>
 * @param resource $context [optional] &note.context-support;
 * @return bool true on success or false on failure.
 * @since 4.0
 * @since 5.0
 */
function unlink ($filename, $context = null) {}

 

2、如何工做的

    1. 固然是使用中間件了

// Http/Kernel.php 文件裏面
class Kernel extends HttpKernel
{
    /**
     * The application's global HTTP middleware stack.
     *
     * @var array
     */
    protected $middleware = [
        
        // 就是這個東西了
        \Illuminate\Foundation\Http\Middleware\CheckForMaintenanceMode::class,
    ];
}

    2. 繼續看中間件的實現

class CheckForMaintenanceMode
{
    /**
     * The application implementation.
     *
     * @var \Illuminate\Contracts\Foundation\Application
     */
    protected $app;

    /**
     * Create a new middleware instance.
     *
     * @param  \Illuminate\Contracts\Foundation\Application  $app
     * @return void
     */
    public function __construct(Application $app)
    {
        $this->app = $app;
    }

    /**
     * Handle an incoming request.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  \Closure  $next
     * @return mixed
     *
     * @throws \Symfony\Component\HttpKernel\Exception\HttpException
     */
    public function handle($request, Closure $next)
    {
       
        // 當這個條件成立時，直接拋出 HttpException(503) 異常。
        // 默認狀況下，該請求會直接顯示 resources/views/errors/503.blade.php 頁面
        if ($this->app->isDownForMaintenance()) {
            throw new HttpException(503);
        }

        return $next($request);
    }
}



// 再看 isDownForMaintenance() 函數

/**
 * Determine if the application is currently down for maintenance.
 *
 * @return bool
 */
public function isDownForMaintenance()
{
    // 重點：判斷一下 laravel的storagePath/framework 下面是否存在 down 文件
    return file_exists($this->storagePath().'/framework/down');
}

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總結：

其實呢，這些只是一個拋磚引玉的過程。只是拿框架的一個小東西來扯扯而已。仍是那句話：路漫漫其修遠兮。加油吧，少年~

1.  php artisan down => 在storagePath/framework 下面建立 down文件； php artisan up => 刪除 down 建立 down文件

2.  laravel 默認中間件，檢查storagePath/framework 下面是否存在down文件，若存在則拋出503異常