什么是Middleware？

Laravel里面很多设置模式的概念，DI[Dependency Injection]， Intercepting Filter 参考J2EE的责任链

用中间件有什么好处

可以帮我们很清晰的分离代码，简化关键逻辑

定义中间件

php artisan make:middleware CheckAge


<?php

namespace App\Http\Middleware;

use Closure;

class CheckAge
{
    /**
     * Handle an incoming request.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  \Closure  $next
     * @return mixed
     */
    public function handle($request, Closure $next)
    {
        if ($request->age > 200) {
            return response(null, 400)->header('Content-Type', 'text/json');
        }

        return $next($request);
    }
}

注册中间件

//app/Http/Kernel.php最后添加 $routeMiddleware

'check.age' => \App\Http\Middleware\CheckAge::class,

Route::middleware('check.age')->post('/user', function (Request $request) {
    return 'user created successful!';
});

讲一个内置的中间件 throttle

用来限制API请求的次数，回内置RESTful API要求的一些 response header

修改app/Http/Kernel.php api => throttle:1,1 每分钟访问1次，超过1次就会报错 「429 Too Many Requests」