图解Laravel的生命周期

先来张图大致理解下laravel的生命周期。

下面对应相应的代码，解释上图。

//文件路径：laravel/public/index.php

/**

 * laravel的启动时间

 */

define('LARAVEL_START', microtime(true));

/**

 * 加载项目依赖。

 * 现代PHP依赖于Composer包管理器，入口文件通过引入由Composer包管理器。

 * 自动生成的类加载程序，可以轻松注册并加载所依赖的第三方组件库。

 */

require __DIR__.'/../vendor/autoload.php';

/**

 * 创建laravel应用实例。

 */

$app = require_once __DIR__.'/../bootstrap/app.php';

// 接受请求并响应

$kernel = $app->make(Illuminate\Contracts\Http\Kernel::class);

$response = $kernel->handle(

    $request = Illuminate\Http\Request::capture()

);

// 结束请求，进行回调

$response->send();

// 终止程序

$kernel->terminate($request, $response);

//文件路径：laravel/boostrap/app.php

//第一部分：创建应用实例

$app = new Illuminate\Foundation\Application(

    realpath(__DIR__.'/../')

);

//第二部分：完成内核绑定

$app->singleton(

    Illuminate\Contracts\Http\Kernel::class,

    App\Http\Kernel::class

);

$app->singleton(

    Illuminate\Contracts\Console\Kernel::class,

    App\Console\Kernel::class

);

$app->singleton(

    Illuminate\Contracts\Debug\ExceptionHandler::class,

    App\Exceptions\Handler::class

);

return $app;

文件路径：laravel\vendor\laravel\framework\src\Illuminate\Foundation\Http\Kernel.php

class Kernel implements KernelContract

{

    protected $bootstrappers = [

        \Illuminate\Foundation\Bootstrap\LoadEnvironmentVariables::class, // 注册系统环境配置

        \Illuminate\Foundation\Bootstrap\LoadConfiguration::class,              // 注册系统配置

        \Illuminate\Foundation\Bootstrap\HandleExceptions::class,              // 注册异常注册

        \Illuminate\Foundation\Bootstrap\RegisterFacades::class,                // 注册门面模式

        \Illuminate\Foundation\Bootstrap\RegisterProviders::class,              // 注册服务提供者

        \Illuminate\Foundation\Bootstrap\BootProviders::class,                    // 注册服务提供者boot

    ];

    // 处理请求

    public function handle($request)

    {

        try {

            $request->enableHttpMethodParameterOverride();

            $response = $this->sendRequestThroughRouter($request);

        } catch (Exception $e) {

            $this->reportException($e);

            $response = $this->renderException($request, $e);

        } catch (Throwable $e) {

            $this->reportException($e = new FatalThrowableError($e));

            $response = $this->renderException($request, $e);

        }

        $this->app['events']->dispatch(

            new Events\RequestHandled($request, $response)

        );

        return $response;

    }

    protected function sendRequestThroughRouter($request)

    {

        //一、将$request实例注册到APP容器

        $this->app->instance('request', $request);

        //二、清除之前的$request实例缓存

        Facade::clearResolvedInstance('request');

        //三、启动引导程序

        $this->bootstrap();

        //四、发送请求

        return (new Pipeline($this->app)) //创建管道

                    ->send($request)      //发送请求

                    ->through($this->app->shouldSkipMiddleware() ? [] : $this->middleware)  //通过中间件

                    ->then($this->dispatchToRouter());  //分发到路由

    }

    // 启动引导程序

    public function bootstrap()

    {

        if (! $this->app->hasBeenBootstrapped()) {

            $this->app->bootstrapWith($this->bootstrappers());

        }

    }

    // 路由分发

    protected function dispatchToRouter()

    {

        return function ($request) {

            $this->app->instance('request', $request);

            return $this->router->dispatch($request);

        };

    }

    // 终止程序

    public function terminate($request, $response)

    {

        $this->terminateMiddleware($request, $response);

        $this->app->terminate();

    }