摘要:學(xué)習(xí)筆記之已經(jīng)聊過使用了來設(shè)計,看源碼發(fā)現(xiàn)其巧妙用了和的一些數(shù)組函數(shù)來設(shè)計。開發(fā)環(huán)境內(nèi)置函數(shù)和看源碼之前,先看下這幾個內(nèi)置函數(shù)的使用。學(xué)習(xí)筆記之實例化源碼解析已經(jīng)聊過的實例化,得到中的變量,即的實例化對象。后面再學(xué)習(xí)下的源碼,到時見。
說明:本文主要學(xué)習(xí)Laravel的Middleware的源碼設(shè)計思想,并將學(xué)習(xí)心得分享出來,希望對別人有所幫助。Laravel學(xué)習(xí)筆記之Decorator Pattern已經(jīng)聊過Laravel使用了Decorator Pattern來設(shè)計Middleware,看Laravel源碼發(fā)現(xiàn)其巧妙用了Closure和PHP的一些數(shù)組函數(shù)來設(shè)計Middleware。
開發(fā)環(huán)境:Laravel5.3 + PHP7 + OS X 10.11
PHP內(nèi)置函數(shù)array_reverse、array_reduce、call_user_func和call_user_func_array看Laravel源碼之前,先看下這幾個PHP內(nèi)置函數(shù)的使用。首先array_reverse()函數(shù)比較簡單,倒置數(shù)組,看測試代碼:
$pipes = [ "Pipe1", "Pipe2", "Pipe3", "Pipe4", "Pipe5", "Pipe6", ]; $pipes = array_reverse($pipes); var_dump($pipes); // output array(6) { [0] => string(5) "Pipe6" [1] => string(5) "Pipe5" [2] => string(5) "Pipe4" [3] => string(5) "Pipe3" [4] => string(5) "Pipe2" [5] => string(5) "Pipe1" }
array_reduce內(nèi)置函數(shù)主要是用回調(diào)函數(shù)去迭代數(shù)組中每一個值,并且每一次回調(diào)得到的結(jié)果值作為下一次回調(diào)的初始值,最后返回最終迭代的值:
/** * @link http://php.net/manual/zh/function.array-reduce.php * @param int $v * @param int $w * * @return int */ function rsum($v, $w) { $v += $w; return $v; } $a = [1, 2, 3, 4, 5]; // 10為初始值 $b = array_reduce($a, "rsum", 10); // 最后輸出 (((((10 + 1) + 2) + 3) + 4) + 5) = 25 echo $b . PHP_EOL;
call_user_func()是執(zhí)行回調(diào)函數(shù),并可輸入?yún)?shù)作為回調(diào)函數(shù)的參數(shù),看測試代碼:
class TestCallUserFunc { public function index($request) { echo $request . PHP_EOL; } } /** * @param $test */ function testCallUserFunc($test) { echo $test . PHP_EOL; } // [$class, $method] call_user_func(["TestCallUserFunc", "index"], "pipes"); // 輸出"pipes" // Closure call_user_func(function ($passable) { echo $passable . PHP_EOL; }, "pipes"); // 輸出"pipes" // function call_user_func("testCallUserFunc" , "pipes"); // 輸出"pipes"
call_user_func_array與call_user_func基本一樣,只不過傳入的參數(shù)是數(shù)組:
class TestCallUserFuncArray { public function index($request) { echo $request . PHP_EOL; } } /** * @param $test */ function testCallUserFuncArray($test) { echo $test . PHP_EOL; } // [$class, $method] call_user_func_array(["TestCallUserFuncArray", "index"], ["pipes"]); // 輸出"pipes" // Closure call_user_func_array(function ($passable) { echo $passable . PHP_EOL; }, ["pipes"]); // 輸出"pipes" // function call_user_func_array("testCallUserFuncArray" , ["pipes"]); // 輸出"pipes"Middleware源碼解析
了解了幾個PHP內(nèi)置函數(shù)后再去看下Middleware源碼就比較簡單了。Laravel學(xué)習(xí)筆記之IoC Container實例化源碼解析已經(jīng)聊過Application的實例化,得到index.php中的$app變量,即IlluminateFoundationApplication的實例化對象。然后繼續(xù)看下index.php的源碼:
/** * @var AppHttpKernel $kernel */ $kernel = $app->make(IlluminateContractsHttpKernel::class); $response = $kernel->handle( $request = IlluminateHttpRequest::capture() ); $response->send(); $kernel->terminate($request, $response);
首先從容器中解析出Kernel對象,對于AppHttpKernel對象的依賴:IlluminateFoundationApplication和IlluminateRoutingRouter,容器會自動解析。看下Kernel的構(gòu)造函數(shù):
/** * Create a new HTTP kernel instance. * * @param IlluminateContractsFoundationApplication $app * @param IlluminateRoutingRouter $router */ public function __construct(Application $app, Router $router) { $this->app = $app; $this->router = $router; foreach ($this->middlewareGroups as $key => $middleware) { $router->middlewareGroup($key, $middleware); } foreach ($this->routeMiddleware as $key => $middleware) { $router->middleware($key, $middleware); } } // IlluminateRoutingRouter內(nèi)的方法 public function middlewareGroup($name, array $middleware) { $this->middlewareGroups[$name] = $middleware; return $this; } public function middleware($name, $class) { $this->middleware[$name] = $class; return $this; }
構(gòu)造函數(shù)初始化了幾個中間件數(shù)組,$middleware[ ], $middlewareGroups[ ]和$routeMiddleware[ ],Laravel5.0的時候記得中間件數(shù)組還沒有分的這么細(xì)。然后就是Request的實例化:
$request = IlluminateHttpRequest::capture()
這個過程以后再聊吧,不管咋樣,得到了IlluminateHttpRequest對象,然后傳入Kernel中:
/** * Handle an incoming HTTP request. * * @param IlluminateHttpRequest $request * @return IlluminateHttpResponse */ public function handle($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); } $this->app["events"]->fire("kernel.handled", [$request, $response]); return $response; }
主要是sendRequestThroughRouter($request)函數(shù)執(zhí)行了轉(zhuǎn)換操作:把IlluminateHttpRequest對象轉(zhuǎn)換成了IlluminateHttpResponse,然后通過Kernel的send()方法發(fā)送給客戶端。同時,順便觸發(fā)了kernel.handled內(nèi)核已處理請求事件。OK,重點關(guān)注下sendRequestThroughRouter($request)方法:
/** * Send the given request through the middleware / router. * * @param IlluminateHttpRequest $request * @return IlluminateHttpResponse */ protected function sendRequestThroughRouter($request) { $this->app->instance("request", $request); Facade::clearResolvedInstance("request"); /* 依次執(zhí)行$bootstrappers中每一個bootstrapper的bootstrap()函數(shù),做了幾件準(zhǔn)備事情: 1. 環(huán)境檢測 2. 配置加載 3. 日志配置 4. 異常處理 5. 注冊Facades 6. 注冊Providers 7. 啟動服務(wù) protected $bootstrappers = [ "IlluminateFoundationBootstrapDetectEnvironment", "IlluminateFoundationBootstrapLoadConfiguration", "IlluminateFoundationBootstrapConfigureLogging", "IlluminateFoundationBootstrapHandleExceptions", "IlluminateFoundationBootstrapRegisterFacades", "IlluminateFoundationBootstrapRegisterProviders", "IlluminateFoundationBootstrapBootProviders", ];*/ $this->bootstrap(); return (new Pipeline($this->app)) ->send($request) ->through($this->app->shouldSkipMiddleware() ? [] : $this->middleware) ->then($this->dispatchToRouter()); }
$this->bootstrap()主要是做了程序初始化工作,以后再聊具體細(xì)節(jié)。然后是Pipeline來傳輸Request,Laravel中把Pipeline管道多帶帶拿出來作為一個service(可看Illuminate/Pipeline文件夾),說明Pipeline做的事情還是很重要的:主要就是作為Request的傳輸管道,依次通過$middlewares[ ], 或middlewareGroups[ ], 或$routeMiddleware[ ]這些中間件的前置操作,和控制器的某個action或者直接閉包處理得到Response,然后又帶著Reponse依次通過$middlewares[ ], 或middlewareGroups[ ], 或$routeMiddleware[ ]這些中間件的后置操作得到準(zhǔn)備就緒的Response,然后通過send()發(fā)送給客戶端。
這個過程有點像汽車工廠的生產(chǎn)一樣,Pipeline是傳送帶,起初Request可能就是個汽車空殼子,經(jīng)過傳送帶旁邊的一個個機(jī)械手middleware@before的過濾和操作(如檢查零件剛度是不是合格,殼子尺寸是不是符合要求,給殼子噴個漆或抹個油啥的),然后進(jìn)入中央控制區(qū)加個發(fā)動機(jī)(Controller@action ,或Closure),然后又繼續(xù)經(jīng)過檢查和附加操作middleware@after(如添加個擋風(fēng)鏡啥的),然后通過門外等著的火車直接運(yùn)送到消費(fèi)者手里send()。在每一步裝配過程中,都需要Service來支持,Service是通過Container來解析{make()}提供的,并且Service是通過ServiceProvider注冊綁定{bind(),singleton(),instance()}到Container中的。
看下Pipeline的send()和through()源碼:
public function send($passable) { $this->passable = $passable; return $this; } public function through($pipes) { $this->pipes = is_array($pipes) ? $pipes : func_get_args(); return $this; }
send()傳送的對象是Request,through()所要通過的對象是$middleware[ ],OK,再看下dispatchToRouter()的源碼直接返回一個Closure:
protected function dispatchToRouter() { return function ($request) { $this->app->instance("request", $request); return $this->router->dispatch($request); }; }
然后重點看下then()函數(shù)源碼:
public function then(Closure $destination) { $firstSlice = $this->getInitialSlice($destination); $pipes = array_reverse($this->pipes); // $this->passable = Request對象 return call_user_func( array_reduce($pipes, $this->getSlice(), $firstSlice), $this->passable ); } protected function getInitialSlice(Closure $destination) { return function ($passable) use ($destination) { return call_user_func($destination, $passable); }; }
這里假設(shè)$middlewares為(盡管源碼中$middlewares只有一個CheckForMaintenanceMode::class):
$middlewares = [ CheckForMaintenanceMode::class, AddQueuedCookiesToResponse::class, StartSession::class, ShareErrorsFromSession::class, VerifyCsrfToken::class, ];
先獲得第一個slice(這里作者是比作"洋蔥",一層層的穿過,從一側(cè)穿過到另一側(cè),比喻倒也形象)并作為array_reduce()的初始值,就像上文中array_reduce()測試?yán)又械?0這個初始值,這個初始值現(xiàn)在是個閉包:
$destination = function ($request) { $this->app->instance("request", $request); return $this->router->dispatch($request); }; $firstSlice = function ($passable) use ($destination) { return call_user_func($destination, $passable); };
OK,然后要對$middlewares[ ]進(jìn)行翻轉(zhuǎn),為啥要翻轉(zhuǎn)呢?
看過這篇Laravel學(xué)習(xí)筆記之Decorator Pattern文章就會發(fā)現(xiàn),在Client類利用Decorator Pattern進(jìn)行依次裝飾的時候,是按照$middlewares[ ]數(shù)組中值倒著new的:
public function wrapDecorator(IMiddleware $decorator) { $decorator = new VerifyCsrfToken($decorator); $decorator = new ShareErrorsFromSession($decorator); $decorator = new StartSession($decorator); $decorator = new AddQueuedCookiesToResponse($decorator); $response = new CheckForMaintenanceMode($decorator); return $response; }
這樣才能得到一個符合$middlewares[ ]順序的$response對象:
$response = new CheckForMaintenanceMode( new AddQueuedCookiesToResponse( new StartSession( new ShareErrorsFromSession( new VerifyCsrfToken( new Request() ) ) ) ) );
看下array_reduce()中的迭代回調(diào)函數(shù)getSlice(){這個迭代回調(diào)函數(shù)比作剝洋蔥時獲取每一層洋蔥slice,初始值是$firstSlice}:
protected function getSlice() { return function ($stack, $pipe) { return function ($passable) use ($stack, $pipe) { if ($pipe instanceof Closure) { return call_user_func($pipe, $passable, $stack); } elseif (! is_object($pipe)) { list($name, $parameters) = $this->parsePipeString($pipe); $pipe = $this->container->make($name); $parameters = array_merge([$passable, $stack], $parameters); } else{ $parameters = [$passable, $stack]; } return call_user_func_array([$pipe, $this->method], $parameters); }; }; }
返回的是個閉包,仔細(xì)看下第二層閉包里的邏輯,這里$middlewares[ ]傳入的是每一個中間件的名字,然后通過容器解析出每一個中間件對象:
$pipe = $this->container->make($name);
并最后用call_user_func_array([$class, $method], array $parameters)來調(diào)用這個$class里的$method方法,參數(shù)是$parameters。
Demo接下來寫個demo看下整個流程。
先簡化下getSlice()函數(shù),這里就默認(rèn)$pipe傳入的是類名稱(整個demo中所有class都在同一個文件內(nèi)):
// PipelineTest.php // Get the slice in every step. function getSlice() { return function ($stack, $pipe) { return function ($passable) use ($stack, $pipe) { /** * @var Middleware $pipe */ return call_user_func_array([$pipe, "handle"], [$passable, $stack]); }; }; }
再把$middlewares[ ]中五個中間件類寫上,對于前置操作和后置操作做個簡化,直接echo字符串:
// PipelineTest.php給上完整的一個Pipeline類,這里的Pipeline對Laravel中的Pipeline做了稍微簡化,只選了幾個重要的函數(shù):
// PipelineTest.php class Pipeline { /** * @var array */ protected $middlewares = []; /** * @var int */ protected $request; // Get the initial slice function getInitialSlice(Closure $destination) { return function ($passable) use ($destination) { return call_user_func($destination, $passable); }; } // Get the slice in every step. function getSlice() { return function ($stack, $pipe) { return function ($passable) use ($stack, $pipe) { /** * @var Middleware $pipe */ return call_user_func_array([$pipe, "handle"], [$passable, $stack]); }; }; } // When process the Closure, send it as parameters. Here, input an int number. function send(int $request) { $this->request = $request; return $this; } // Get the middlewares array. function through(array $middlewares) { $this->middlewares = $middlewares; return $this; } // Run the Filters. function then(Closure $destination) { $firstSlice = $this->getInitialSlice($destination); $pipes = array_reverse($this->middlewares); $run = array_reduce($pipes, $this->getSlice(), $firstSlice); return call_user_func($run, $this->request); } }OK,現(xiàn)在開始傳入Request,這里簡化為一個整數(shù)而不是Request對象了:
// PipelineTest.php /** * @return Closure */ function dispatchToRouter() { return function ($request) { echo $request . ": Send Request to the Kernel, and Return Response." . PHP_EOL; }; } $request = 10; $middlewares = [ CheckForMaintenanceMode::class, AddQueuedCookiesToResponse::class, StartSession::class, ShareErrorsFromSession::class, VerifyCsrfToken::class, ]; (new Pipeline())->send($request)->through($middlewares)->then(dispatchToRouter());執(zhí)行php PipelineTest.php得到Response:
10: Check if the application is in the maintenance status. 10: Start session of this request. 10: Verify csrf token when post request. 10: Send Request to the Kernel, and Return Response. 10: Share the errors variable from response to the views. 10: Close session of this response. 10: Add queued cookies to the response.一步一步分析下執(zhí)行過程:
1.首先獲取$firstSlice
$destination = function ($request) { echo $request . ": Send Request to the Kernel, and Return Response." . PHP_EOL; }; $firstSlice = function ($passable) use ($destination) { return call_user_func($destination, $passable); };這時經(jīng)過初始化后:
$this->request = 10; $pipes = [ VerifyCsrfToken::class, ShareErrorsFromSession::class, StartSession::class, AddQueuedCookiesToResponse::class, CheckForMaintenanceMode::class, ];2.執(zhí)行第一次getSlice()后的結(jié)果作為新的$stack,其值為:
$stack = $firstSlice; $pipe = VerifyCsrfToken::class; $stack_1 = function ($passable) use ($stack, $pipe) { /** * @var Middleware $pipe */ return call_user_func_array([$pipe, "handle"], [$passable, $stack]); };3.執(zhí)行第二次getSlice()后的結(jié)果作為新的$stack,其值為:
$stack = $stack_1; $pipe = ShareErrorsFromSession::class; $stack_2 = function ($passable) use ($stack, $pipe) { /** * @var Middleware $pipe */ return call_user_func_array([$pipe, "handle"], [$passable, $stack]); };4.執(zhí)行第三次getSlice()后的結(jié)果作為新的$stack,其值為:
$stack = $stack_2; $pipe = StartSession::class; $stack_3 = function ($passable) use ($stack, $pipe) { /** * @var Middleware $pipe */ return call_user_func_array([$pipe, "handle"], [$passable, $stack]); };5.執(zhí)行第四次getSlice()后的結(jié)果作為新的$stack,其值為:
$stack = $stack_3; $pipe = AddQueuedCookiesToResponse::class; $stack_4 = function ($passable) use ($stack, $pipe) { /** * @var Middleware $pipe */ return call_user_func_array([$pipe, "handle"], [$passable, $stack]); };6.執(zhí)行第五次getSlice()后的結(jié)果作為新的$stack,其值為:
$stack = $stack_4; $pipe = CheckForMaintenanceMode::class; $stack_5 = function ($passable) use ($stack, $pipe) { /** * @var Middleware $pipe */ return call_user_func_array([$pipe, "handle"], [$passable, $stack]); };這時,$stack_5也就是then()里的$run,然后執(zhí)行call_user_func($run, 10),看執(zhí)行過程:
1.$stack_5(10) = CheckForMaintenanceMode::handle(10, $stack_4)
echo "10: Check if the application is in the maintenance status." . PHP_EOL; stack_4(10);2.$stack_4(10) = AddQueuedCookiesToResponse::handle(10, $stack_3)
$stack_3(10); echo "10: Add queued cookies to the response." . PHP_EOL;3.$stack_3(10) = StartSession::handle(10, $stack_2)
echo "10: Start session of this request." . PHP_EOL; $stack_2(10); echo "10: Close session of this response." . PHP_EOL;4.$stack_2(10) = ShareErrorsFromSession::handle(10, $stack_1)
$stack_1(10); echo "10: Share the errors variable from response to the views." . PHP_EOL;5.$stack_1(10) = VerifyCsrfToken::handle(10, $firstSlice)
echo "10: Verify csrf token when post request." . PHP_EOL; $firstSlice(10);6.$firstSlice(10) =
$firstSlice(10) = call_user_func($destination, 10) = echo "10: Send Request to the Kernel, and Return Response." . PHP_EOL;OK,再把上面執(zhí)行順序整理一下:
1. echo "10: Check if the application is in the maintenance status." . PHP_EOL; // 第一個step 3_1. echo "10: Start session of this request." . PHP_EOL; // 第三個step 5. echo "10: Verify csrf token when post request." . PHP_EOL; // 第五個step 6.echo "10: Send Request to the Kernel, and Return Response." . PHP_EOL; //第六個step 4. echo "10: Share the errors variable from response to the views." . PHP_EOL; // 第四個step 3_2. echo "10: Close session of this response." . PHP_EOL; // 第三個step 2. echo "10: Add queued cookies to the response." . PHP_EOL; // 第二個step經(jīng)過上面的一步步分析,就能很清楚Laravel源碼中Middleware的執(zhí)行步驟了。再復(fù)雜的步驟只要一步步拆解,就很清晰每一步的邏輯,然后把步驟組裝,就能知道全貌了。
總結(jié):本文主要學(xué)習(xí)了Laravel的Middleware的源碼,學(xué)習(xí)完后就知道沒有什么神秘之處,只需要動手一步步拆解就行。后面再學(xué)習(xí)下Container的源碼,到時見。
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