中间件：还在使用trim过滤请求参数吗?

中间件

什么是中间件，概念性东西用文字描述是不易懂得。直接看案例。

使用场景

在接收请求参数，通常会使用trim()函数过滤参数两边的多余空格。
laravel框架默认全局中间件\App\Http\Middleware\TrimStrings::class中间件会在请求到达控制器之前【也称为前置中间件】，进行trim()处理。也意味着你不再需要进行参数trim过滤。

<?php

namespace Illuminate\Foundation\Http\Middleware;

class TrimStrings extends TransformsRequest
{
    /**
     * The attributes that should not be trimmed.
     *
     * @var array
     */
    protected $except = [
        //
    ];

    /** (备注：此函数在父类TransformsRequest中)
     * Handle an incoming request. * * @param \Illuminate\Http\Request  $request
     * @param \Closure  $next
     * @return mixed
     */public function handle($request, Closure $next)
    {
        $this->clean($request);
        return $next($request);
    }

    /**
     * Transform the given value.
     *
     * @param  string  $key
     * @param  mixed  $value
     * @return mixed
     */
    protected function transform($key, $value)
    {
        if (in_array($key, $this->except, true)) {
            return $value;
        }

        return is_string($value) ? trim($value) : $value;
    }
}

前置中间件：在请求到达控制器之前执行(用得比较多)，
后置中间件：在请求到达控制器执行完后执行(用得少一点)

定义中间件

php artisan make:middleware EnsureTokenIsValid

此命令将在您的 app/Http/Middleware 目录中放置一个新的 EnsureTokenIsValid 类。

在这个中间件中，如果提供的 token 输入匹配指定的值，我们将只允许访问路由。否则，我们会将用户重定向回 home URI：

<?php

namespace App\Http\Middleware;

use Closure;

class EnsureTokenIsValid
{
    /**
     * Handle an incoming request.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  \Closure  $next
     * @return mixed
     */
    public function handle($request, Closure $next)
    {
        //前置中间件
        if ($request->input('token') !== 'my-secret-token') {
            return redirect('home');
        }

        return $next($request);
    }

    /*
    public function handle($request, Closure $next)
    {
        //后置中间件
        $response  =  $next($request);
        //do something
        return $response;
    }
    */
}

注册中间件

全局中间件

如果您希望在对应用程序的每个 HTTP 请求期间运行中间件，请在 app/Http/Kernel.php 类的 $middleware 属性中列出中间件类。

<?php

namespace App\Http;

use Illuminate\Foundation\Http\Kernel as HttpKernel;

class Kernel extends HttpKernel
{
    /**
     * The application's global HTTP middleware stack.
     *
     * These middleware are run during every request to your application.
     *
     * @var array
     */
    protected $middleware = [
        \App\Http\Middleware\TrustHosts::class,
        \App\Http\Middleware\TrustProxies::class,
        \Fruitcake\Cors\HandleCors::class,
        \App\Http\Middleware\PreventRequestsDuringMaintenance::class,
        \Illuminate\Foundation\Http\Middleware\ValidatePostSize::class,
        \App\Http\Middleware\TrimStrings::class,
        \Illuminate\Foundation\Http\Middleware\ConvertEmptyStringsToNull::class,
        \App\Http\Middleware\EnsureTokenIsValid::class,
    ];

将中间件分配给路由

如果您想将中间件分配给特定的路由，您应该首先在应用程序的 app/Http/Kernel.php 文件中为中间件分配一个键。

// 在 App\Http\Kernel 类中...
protected $routeMiddleware = [
    'auth' => \App\Http\Middleware\Authenticate::class,
    'auth.basic' => \Illuminate\Auth\Middleware\AuthenticateWithBasicAuth::class,
    'cache.headers' => \Illuminate\Http\Middleware\SetCacheHeaders::class,
    'can' => \Illuminate\Auth\Middleware\Authorize::class,
    'guest' => \App\Http\Middleware\RedirectIfAuthenticated::class,
    'password.confirm' => \Illuminate\Auth\Middleware\RequirePassword::class,
    'signed' => \Illuminate\Routing\Middleware\ValidateSignature::class,
    'throttle' => \Illuminate\Routing\Middleware\ThrottleRequests::class,
    'verified' => \Illuminate\Auth\Middleware\EnsureEmailIsVerified::class,
    'ensure.token' => \App\Http\Middleware\EnsureTokenIsValid::class,
];