由于某种原因，公司整体框架由python的flask框架，转换为php的laravel。在断断续续几个月的时间里，边继续写着flask框架，边学着laravel。说下自己现在的状态吧。前段时间差不多都在个1-2点睡觉，大概四月份有段时间竟然到了3-4点才睡的地步。

路漫漫其修远兮，总感觉时间不够用的。大概是自己之前浪费的时间太多了，是时候还上了。

laravel文档中文版的，大概看到过三个。随便找个看看就可以了。http://laravel-china.org/docs/5.1

# 输入 php artisan 即可看到全部可用命令down                 Put the application into maintenance modeup                   Bring the application out of maintenance mode

整体流程大体（因为详细的我也不是很清楚╮(╯_╰)╭）说下吧。

一、命令的实现

1. 作为服务提供者，加载到程序中。

// config/app.php 中。
'providers' => [// 这个便是 laravel自带的 artisan 命令提供者Illuminate\Foundation\Providers\ArtisanServiceProvider::class,
]

2.然后找到 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实现

class DownCommand extends Command
{/*** The console command name.** @var string*/protected $name = 'down';/*** The console command description.** @var string*/protected $description = 'Put the application into maintenance mode';/*** Execute the console command.** @return void*/public function fire(){// 关键点： 在当前存储目录/framework 下面创建一个 down文件touch($this->laravel->storagePath().'/framework/down');$this->comment('Application is now in maintenance mode.');}
}// touch() 函数php文档解释
/*** 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 实现

class UpCommand extends Command
{/*** The console command name.** @var string*/protected $name = 'up';/*** The console command description.** @var string*/protected $description = 'Bring the application out of maintenance mode';/*** Execute the console command.** @return void*/public function fire(){// 关键：删除laravel存储目录/fromework 下面的 down 文件@unlink($this->laravel->storagePath().'/framework/down');$this->info('Application is now live.');}
}// @unlink() php文档解释
/*** 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) {}

二、如何工作的

1. 当然是使用中间件了

// Http/Kernel.php 文件里面
class Kernel extends HttpKernel
{/*** The application's global HTTP middleware stack.** @var array*/protected $middleware = [// 就是这个东西了\Illuminate\Foundation\Http\Middleware\CheckForMaintenanceMode::class,];
}

2. 继续看中间件的实现

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 $next){// 当这个条件成立时，直接抛出 HttpException(503) 异常。// 默认情况下，该请求会直接显示 resources/views/errors/503.blade.php 页面if ($this->app->isDownForMaintenance()) {throw new HttpException(503);}return $next($request);}
}// 再看 isDownForMaintenance() 函数/*** Determine if the application is currently down for maintenance.** @return bool*/
public function isDownForMaintenance()
{// 重点：判断一下 laravel的storagePath/framework 下面是否存在 down 文件return file_exists($this->storagePath().'/framework/down');
}

总结：

其实呢，这些只是一个抛砖引玉的过程。只是拿框架的一个小东西来扯扯而已。还是那句话：路漫漫其修远兮。加油吧，少年~

1.  php artisan down => 在storagePath/framework 下面创建 down文件； php artisan up => 删除 down 创建 down文件

2.  laravel 默认中间件，检查storagePath/framework 下面是否存在down文件，若存在则抛出503异常