中間件是什么?
每個中間件是一個定義了handle方法的類或是一個匿名函數，一般所有中間件放在同一個文件夾middleware中，方便管理
public function handle($request, Closure $next)
中間件有什么用

一: 路由前中間件(也叫全局中間件)

這些中間件，在根據請求找到匹配的路由之前就開始執行

1.配置

// 在 \App\Http\Kernel::$middleware中定義，是一個數組，如 $middleware = [\Illuminate\Foundation\Http\Middleware\CheckForMaintenanceMode::class,\Illuminate\Foundation\Http\Middleware\ValidatePostSize::class,\App\Http\Middleware\TrimStrings::class,\Illuminate\Foundation\Http\Middleware\ConvertEmptyStringsToNull::class,\App\Http\Middleware\TrustProxies::class, ];// 在 \Zhiyi\Plus\Http\Kernel::$middleware的值為 $middleware = [\Zhiyi\Plus\Http\Middleware\CrossDomain::class,\Illuminate\Foundation\Http\Middleware\CheckForMaintenanceMode::class,\Illuminate\Foundation\Http\Middleware\ValidatePostSize::class,\Zhiyi\Plus\Http\Middleware\TrimStrings::class,\Illuminate\Foundation\Http\Middleware\ConvertEmptyStringsToNull::class,\Zhiyi\Plus\Http\Middleware\TrustProxies::class, ];

2.執行順序

是按上下執行，這里面的中間執行完后，再執行\Illuminate\Foundation\Http\Kernel::dispatchToRouter()

框架內置的中間件放在Illuminate\Foundation\Http\Middleware下面，一共有6個

二： 路由中間件

這些中間件是在路由匹配之后，與當前匹配路由及控制器有關

1: 在控制器中定義

在控制器的構造函數中定義

public function __construct(){$this->middleWare('auth');$this->middleWare('log',['only'=>['show','detail']]); }

覆蓋getMiddleware()方法

public function getMiddleware(){return ['auth','log',['middleware'=>'hello','options'=>['only'=>['index','show']]]]; }

2: 在路由中定義

在第二個參數中定義middleware

Route::get('/login',['uses'=>'LoginController@index','middleware'=>['abc','def'] ])

直接給路由使用middleware()方法

Route::get('/login','')->middleware('中間件1'，'中間件2');//數組也行

在group中定義

Route::group(['middleware' => ['has-permission:access-dashboard']], function (Router $router) use ($adminRoute) {... });

為什么全局中間件是一個完整的類名，而路由中間件是鍵名或群組名
鍵名或群組名其實是對應一個中間件類，它們的對應關系在Kernel中定義，如

kernel中 $routeMiddleware 對應 router中 middleware屬性 kernel中 $middlewareGroups 對應 router中 middlewareGroups屬性$routeMiddleware = [別名 => 有handle方法的類名或匿名函數'auth' => \Illuminate\Auth\Middleware\Authenticate::class,'auth.basic' => \Illuminate\Auth\Middleware\AuthenticateWithBasicAuth::class,'bindings' => \Illuminate\Routing\Middleware\SubstituteBindings::class,'can' => \Illuminate\Auth\Middleware\Authorize::class,'guest' => \Zhiyi\Plus\Http\Middleware\RedirectIfAuthenticated::class,'throttle' => \Illuminate\Routing\Middleware\ThrottleRequests::class,'ability' => \Zhiyi\Plus\Http\Middleware\UserAbility::class,'sensitive' => \Zhiyi\Plus\Http\Middleware\DisposeSensitive::class,'operation' => \Zhiyi\Plus\Http\Middleware\SensitiveOperation::class,'wang' => function(){這是一個閉包} ];$middlewareGroups = ['web' => [\Zhiyi\Plus\Http\Middleware\EncryptCookies::class,\Illuminate\Cookie\Middleware\AddQueuedCookiesToResponse::class,\Illuminate\Session\Middleware\StartSession::class,// \Illuminate\Session\Middleware\AuthenticateSession::class,\Illuminate\View\Middleware\ShareErrorsFromSession::class,\Zhiyi\Plus\Http\Middleware\VerifyCsrfToken::class,\Illuminate\Routing\Middleware\SubstituteBindings::class,'api' //可以是另一組名,這樣，如果指定的中間件中web，那么包括上面的和api組中合起來的所有中間件'wang' // 也可以是$routeMiddleware中的一個別名(鍵名)],'api' => ['throttle:120,1',// :前面是中間件名，:后面是參數'bindings',],'admin' => ['ability:admin: login,你沒有權限訪問后臺。',], ];

路由中間件在進入管道之前，會轉為以下一個由完整類名組成的一維數組

Array([0] => Illuminate\Routing\Middleware\ThrottleRequests:120,1[1] => Illuminate\Cookie\Middleware\AddQueuedCookiesToResponse[2] => Illuminate\Session\Middleware\StartSession[3] => Illuminate\View\Middleware\ShareErrorsFromSession[4] => Zhiyi\Plus\Http\Middleware\VerifyCsrfToken[5] => Illuminate\Routing\Middleware\SubstituteBindings )

中間件的格式

別名
$this->middleWare('auth');

組名

$this->middleWare('api')

閉包

$this->middleWare(function($request,$next){})

完整類名 $this->middleWare(IlluminateRoutingMiddlewareThrottleRequests)

三: 使用場景

全局中間件

new Pipeline($this->app))->send($request) ->through($this->middleware) ->then($this->dispatchToRouter())

路由中間件

new Pipeline($this->container))->send($request)->through($middleware)->then(function ($request) use ($route) { return $this->prepareResponse($request, $route->run());} );

總結

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