前言
本文主要分析Yii2应用的启动、运行的过程，主要包括以下三部分：入口脚本、启动应用、运行应用。
入口脚本
<?php
// 定义全局变量
defined('YII_DEBUG') or define('YII_DEBUG', true);
defined('YII_ENV') or define('YII_ENV', 'dev');
// composer自动加载代码机制，可参考 https://segmentfault.com/a/1190000010788354
require __DIR__ . '/../vendor/autoload.php';
// 1.引入工具类Yii
// 2.注册自动加载函数
// 3.生成依赖注入中使用到的容器
require __DIR__ . '/../vendor/yiisoft/yii2/Yii.php';
// 加载应用配置文件
$config = require __DIR__ . '/../config/web.php';
//生成应用实例并运行
(new yii\web\Application($config))->run();
启动应用
1.分析：new yii\web\Application($config)
主要就是执行父类构造函数（代码位置：vendor\yiisoft\yii2\base\Application.php）
public function __construct($config = [])
{
// 将Yii::$app 保存为当前对象
Yii::$app = $this;
// 见分析2
static::setInstance($this);
// 设置当前应用状态
$this->state = self::STATE_BEGIN;
// 进行一些预处理（根据$config配置应用）
// 详细代码位置：yii\base\Application::preInit(&$config) 见分析3
$this->preInit($config);
//注册ErrorHandler，这样一旦抛出了异常或错误，就会由其负责处理
//代码位置：yii\base\Application::registerErrorHandler(&$config) 见分析4
$this->registerErrorHandler($config);
// 根据$config配置Application
// 然后执行yii\web\Application::init()（实际上是执行yii\base\Application::init()）见分析5
Component::__construct($config);
}
2.分析：yii\base\Module::setInstance($instance)
/**
* Sets the currently requested instance of this module class.
* @param Module|null $instance the currently requested instance of this module class.
* If it is `null`, the instance of the calling class will be removed, if any.
*/
public static function setInstance($instance)
{
if ($instance === null) {
unset(Yii::$app->loadedModules[get_called_class()]);
} else {
// 将Application实例本身记录为“已加载模块”
Yii::$app->loadedModules[get_class($instance)] = $instance;
}
}
3.分析：yii\base\Application::preInit(&$config)
/**
* Pre-initializes the application.
* This method is called at the beginning of the application constructor.
* It initializes several important application properties.
* If you override this method, please make sure you call the parent implementation.
* @param array $config the application configuration
* @throws InvalidConfigException if either [[id]] or [[basePath]] configuration is missing.
*/
public function preInit(&$config)
{
// 1.判断$config中是否有配置项‘id’，‘basePath’（必须有,否则抛异常）
if (!isset($config['id'])) {
throw new InvalidConfigException('The "id" configuration for the Application is required.');
}
if (isset($config['basePath'])) {
$this->setBasePath($config['basePath']);
unset($config['basePath']);
} else {
throw new InvalidConfigException('The "basePath" configuration for the Application is required.');
}
// 2.设置别名：@vendor，@runtime
if (isset($config['vendorPath'])) {
$this->setVendorPath($config['vendorPath']);
unset($config['vendorPath']);
} else {
// set "@vendor"
$this->getVendorPath();
}
if (isset($config['runtimePath'])) {
$this->setRuntimePath($config['runtimePath']);
unset($config['runtimePath']);
} else {
// set "@runtime"
$this->getRuntimePath();
}
// 3.设置时间区域（timeZone）
if (isset($config['timeZone'])) {
$this->setTimeZone($config['timeZone']);
unset($config['timeZone']);
} elseif (!ini_get('date.timezone')) {
$this->setTimeZone('UTC');
}
// 4.自定义配置容器（Yii::$container）的属性（由这里我们知道可以自定义配置容器）
if (isset($config['container'])) {
$this->setContainer($config['container']);
unset($config['container']);
}
// 5.合并核心组件配置到自定义组件配置：数组$config['components']
//（核心组件有哪些参考：yii\web\Application::coreComponents()）
//（注意：这个方法中$config使用了引用，所以合并$config['components']可以改变$config原来的值）
// merge core components with custom components
foreach ($this->coreComponents() as $id => $component) {
if (!isset($config['components'][$id])) {
$config['components'][$id] = $component;
} elseif (is_array($config['components'][$id]) && !isset($config['components'][$id]['class'])) {
$config['components'][$id]['class'] = $component['class'];
}
}
}
4.分析：yii\base\Application::registerErrorHandler(&$config)
/**
* Registers the errorHandler component as a PHP error handler.
* @param array $config application config
*/
protected function registerErrorHandler(&$config)
{
if (YII_ENABLE_ERROR_HANDLER) {
if (!isset($config['components']['errorHandler']['class'])) {
echo "Error: no errorHandler component is configured.\n";
exit(1);
}
$this->set('errorHandler', $config['components']['errorHandler']);
unset($config['components']['errorHandler']);
$this->getErrorHandler()->register();
}
}
// 默认config文件关于error handler的配置，这里的配置会合并到Yii2本身对核心组件的定义中去（），核心组件的定义在yii\web\Application::coreComponents()
'components' => [
'errorHandler' => [
'errorAction' => 'site/error',
],
],
// yii\base\ErrorHandler::register()
/**
* Register this error handler.
* @since 2.0.32 this will not do anything if the error handler was already registered
*/
public function register()
{
if (!$this->_registered) {
// 该选项设置是否将错误信息作为输出的一部分显示到屏幕，
// 或者对用户隐藏而不显示。
ini_set('display_errors', false);
// 当抛出异常且没有被catch的时候,由yii\base\ErrorHandler::handleException（）处理
set_exception_handler([$this, 'handleException']);
if (defined('HHVM_VERSION')) {
set_error_handler([$this, 'handleHhvmError']);
} else {
// 当出现error的时候由yii\base\ErrorHandler::handleError（）处理
set_error_handler([$this, 'handleError']);
}
if ($this->memoryReserveSize > 0) {
$this->_memoryReserve = str_repeat('x', $this->memoryReserveSize);
}
// 当出现fatal error的时候由yii\base\ErrorHandler::handleFatalError（）处理
register_shutdown_function([$this, 'handleFatalError']);
$this->_registered = true;
}
}
一个值得注意的地方:
在handleException()、handleError()、handleFatalError()中会直接或间接调用yii\web\ErrorHandle::renderException(),而在这个函数里面，有以下这一行代码
$result = Yii::$app->runAction($this->errorAction);
回顾上面config文件中对errorAction这个属性的定义，我们知道可以通过自定义一个action用于在异常或错误时显示自定义的出错页面
例如yii2中默认使用’site/error’这个action来处理
5.分析：Component::__construct($config)
（代码实际位置：/vendor/yiisoft/yii2/base/BaseObject.php）
/**
* Constructor.
*
* The default implementation does two things:
*
* - Initializes the object with the given configuration `$config`.
* - Call [[init()]].
*
* If this method is overridden in a child class, it is recommended that
*
* - the last parameter of the constructor is a configuration array, like `$config` here.
* - call the parent implementation at the end of the constructor.
*
* @param array $config name-value pairs that will be used to initialize the object properties
*/
public function __construct($config = [])
{
if (!empty($config)) {
// 见下面的详细分析
Yii::configure($this, $config);
}
// 跳转到yii\base\Application::init()，见下面的分析
$this->init();
}
/**
* Configures an object with the initial property values.
* @param object $object the object to be configured
* @param array $properties the property initial values given in terms of name-value pairs.
* @return object the object itself
*/
//Yii::configure($object, $properties)分析
//实际上就是为Application的属性赋值
//注意：这里会触发一些魔术方法,间接调用了：
//yii\web\Application::setHomeUrl()
//yii\di\ServiceLocator::setComponents()（这个值得注意，详细参考本文后续“5.1分析”）
//yii\base\Module::setModules()
public static function configure($object, $properties)
{
foreach ($properties as $name => $value) {
$object->$name = $value;
}
return $object;
}
/**
* {@inheritdoc}
*/
// yii\base\Application::init()分析
public function init()
{
// 设置当前应用状态
$this->state = self::STATE_INIT;
// 见下面的bootstrap()方法
$this->bootstrap();
}
/**
* Initializes extensions and executes bootstrap components.
* This method is called by [[init()]] after the application has been fully configured.
* If you override this method, make sure you also call the parent implementation.
*/
protected function bootstrap()
{
if ($this->extensions === null) {
// @vendor/yiisoft/extensions.php是一些关于第三方扩展的配置，当用composer require安装第三扩展的时候就会将新的扩展的相关信息记录到该文件，这样我们就可以在代码中调用了
$file = Yii::getAlias('@vendor/yiisoft/extensions.php');
$this->extensions = is_file($file) ? include $file : [];
}
foreach ($this->extensions as $extension) {
if (!empty($extension['alias'])) {
foreach ($extension['alias'] as $name => $path) {
Yii::setAlias($name, $path);
}
}
// 进行一些必要的预启动
if (isset($extension['bootstrap'])) {
$component = Yii::createObject($extension['bootstrap']);
if ($component instanceof BootstrapInterface) {
Yii::debug('Bootstrap with ' . get_class($component) . '::bootstrap()', __METHOD__);
$component->bootstrap($this);
} else {
Yii::debug('Bootstrap with ' . get_class($component), __METHOD__);
}
}
}
// 预启动，通常会包括‘log’组件，‘debug’模块和‘gii’模块（参考配置文件）
foreach ($this->bootstrap as $mixed) {
$component = null;
if ($mixed instanceof \Closure) {
Yii::debug('Bootstrap with Closure', __METHOD__);
if (!$component = call_user_func($mixed, $this)) {
continue;
}
} elseif (is_string($mixed)) {
if ($this->has($mixed)) {
$component = $this->get($mixed);
} elseif ($this->hasModule($mixed)) {
$component = $this->getModule($mixed);
} elseif (strpos($mixed, '\\') === false) {
throw new InvalidConfigException("Unknown bootstrapping component ID: $mixed");
}
}
if (!isset($component)) {
$component = Yii::createObject($mixed);
}
if ($component instanceof BootstrapInterface) {
Yii::debug('Bootstrap with ' . get_class($component) . '::bootstrap()', __METHOD__);
$component->bootstrap($this);
} else {
Yii::debug('Bootstrap with ' . get_class($component), __METHOD__);
}
}
}
在完成了上面的流程之后，应用就算启动成功了，可以开始运行，处理请求了。
运行应用
1.分析：yii\base\Application::run()
在上面的构造函数执行完后，开始运行应用。即下面这行代码的run()部分
(new yii\web\Application($config))->run();//（实际上执行的是yii\base\Application::run()）
/**
* Runs the application.
* This is the main entrance of an application.
* @return int the exit status (0 means normal, non-zero values mean abnormal)
*/
public function run()
{
try {
$this->state = self::STATE_BEFORE_REQUEST;
// 触发事件’beforeRequest’,依次执行该事件的handler，
$this->trigger(self::EVENT_BEFORE_REQUEST);
$this->state = self::STATE_HANDLING_REQUEST;
//处理请求，这里的返回值是yii\web\Response实例
//handleRequest(),详细参考本文后续“分析2”
$response = $this->handleRequest($this->getRequest());
$this->state = self::STATE_AFTER_REQUEST;
// 触发事件’afterRequest’,依次执行该事件的handler
$this->trigger(self::EVENT_AFTER_REQUEST);
$this->state = self::STATE_SENDING_RESPONSE;
// 发送响应,详细参考本文后续“分析3”
$response->send();
$this->state = self::STATE_END;
return $response->exitStatus;
} catch (ExitException $e) {
// 结束运行
$this->end($e->statusCode, isset($response) ? $response : null);
return $e->statusCode;
}
}
2.分析： yii\web\Application::handleRequest()
/**
* Handles the specified request.
* @param Request $request the request to be handled
* @return Response the resulting response
* @throws NotFoundHttpException if the requested route is invalid
*/
public function handleRequest($request)
{
if (empty($this->catchAll)) {
try {
// 从请求中解析路由和参数，这里会调用urlManager组件来处理
list($route, $params) = $request->resolve();
} catch (UrlNormalizerRedirectException $e) {
$url = $e->url;
if (is_array($url)) {
if (isset($url[0])) {
// ensure the route is absolute
$url[0] = '/' . ltrim($url[0], '/');
}
$url += $request->getQueryParams();
}
// 当解析请求出现异常时进行重定向
return $this->getResponse()->redirect(Url::to($url, $e->scheme), $e->statusCode);
}
} else {
// ’catchAll’参数可以在配置文件中自定义，可用于在项目需要临时下线维护时给出一个统一的访问路由
$route = $this->catchAll[0];
$params = $this->catchAll;
unset($params[0]);
}
try {
Yii::debug("Route requested: '$route'", __METHOD__);
// 记录下当前请求的route
$this->requestedRoute = $route;
// 执行路由相对应的action（yii\base\Module::runAction()详细参考本文后续“分析3”）
$result = $this->runAction($route, $params);
if ($result instanceof Response) {
return $result;
}
// 如果action的返回结果不是Response的实例，则将结果封装到Response实例的data属性中
$response = $this->getResponse();
if ($result !== null) {
$response->data = $result;
}
return $response;
} catch (InvalidRouteException $e) {
throw new NotFoundHttpException(Yii::t('yii', 'Page not found.'), $e->getCode(), $e);
}
}
3.分析： yii\base\Module::runAction()
public function runAction($route, $params = [])
{
//根据路由创建Controller实例（详细参考本文后续“分析4”）
$parts = $this->createController($route);
if (is_array($parts)) {
/* @var $controller Controller */
// 解析出控制器和方法
list($controller, $actionID) = $parts;
$oldController = Yii::$app->controller;
// 设置当前的Controller实例
Yii::$app->controller = $controller;
// 执行action（yii\base\Controller::runAction()详细参考本文后续“分析5”）
$result = $controller->runAction($actionID, $params);
if ($oldController !== null) {
//可以看做是栈
Yii::$app->controller = $oldController;
}
return $result;
}
$id = $this->getUniqueId();
throw new InvalidRouteException('Unable to resolve the request "' . ($id === '' ? $route : $id . '/' . $route) . '".');
}
4.分析： yii\base\Module::createController()
/**
* Creates a controller instance based on the given route.
*
* The route should be relative to this module. The method implements the following algorithm
* to resolve the given route:
*
* 1. If the route is empty, use [[defaultRoute]];
* 2. If the first segment of the route is found in [[controllerMap]], create a controller
* based on the corresponding configuration found in [[controllerMap]];
* 3. If the first segment of the route is a valid module ID as declared in [[modules]],
* call the module's `createController()` with the rest part of the route;
* 4. The given route is in the format of `abc/def/xyz`. Try either `abc\DefController`
* or `abc\def\XyzController` class within the [[controllerNamespace|controller namespace]].
*
* If any of the above steps resolves into a controller, it is returned together with the rest
* part of the route which will be treated as the action ID. Otherwise, `false` will be returned.
*
* @param string $route the route consisting of module, controller and action IDs.
* @return array|bool If the controller is created successfully, it will be returned together
* with the requested action ID. Otherwise `false` will be returned.
* @throws InvalidConfigException if the controller class and its file do not match.
*/
public function createController($route)
{
// 如果route为空则设置route为默认路由，这个可以在配置文件中自定义
if ($route === '') {
$route = $this->defaultRoute;
}
// double slashes or leading/ending slashes may cause substr problem
$route = trim($route, '/');
if (strpos($route, '//') !== false) {
return false;
}
if (strpos($route, '/') !== false) {
list($id, $route) = explode('/', $route, 2);
} else {
$id = $route;
$route = '';
}
// 优先使用controllerMap，controllerMap可以如下
// module and controller map take precedence
if (isset($this->controllerMap[$id])) {
$controller = Yii::createObject($this->controllerMap[$id], [$id, $this]);
return [$controller, $route];
}
// 先判断是否存在相应的模块
$module = $this->getModule($id);
if ($module !== null) {
// 当存在模块时，进行递归
return $module->createController($route);
}
if (($pos = strrpos($route, '/')) !== false) {
$id .= '/' . substr($route, 0, $pos);
$route = substr($route, $pos + 1);
}
// 最终找到Controller的id
$controller = $this->createControllerByID($id);
if ($controller === null && $route !== '') {
// 详细见下面的代码分析
$controller = $this->createControllerByID($id . '/' . $route);
$route = '';
}
// 返回Controller实例和剩下的路由信息
return $controller === null ? false : [$controller, $route];
}
/**
* Creates a controller based on the given controller ID.
*
* The controller ID is relative to this module. The controller class
* should be namespaced under [[controllerNamespace]].
*
* Note that this method does not check [[modules]] or [[controllerMap]].
*
* @param string $id the controller ID.
* @return Controller|null the newly created controller instance, or `null` if the controller ID is invalid.
* @throws InvalidConfigException if the controller class and its file name do not match.
* This exception is only thrown when in debug mode.
*/
public function createControllerByID($id)
{
$pos = strrpos($id, '/');
if ($pos === false) {
$prefix = '';
$className = $id;
} else {
$prefix = substr($id, 0, $pos + 1);
$className = substr($id, $pos + 1);
}
if ($this->isIncorrectClassNameOrPrefix($className, $prefix)) {
return null;
}
$className = preg_replace_callback('%-([a-z0-9_])%i', function ($matches) {
return ucfirst($matches[1]);
}, ucfirst($className)) . 'Controller';
$className = ltrim($this->controllerNamespace . '\\' . str_replace('/', '\\', $prefix) . $className, '\\');
if (strpos($className, '-') !== false || !class_exists($className)) {
return null;
}
if (is_subclass_of($className, 'yii\base\Controller')) {
// 通过依赖注入容器获得Controller实例
$controller = Yii::createObject($className, [$id, $this]);
return get_class($controller) === $className ? $controller : null;
} elseif (YII_DEBUG) {
throw new InvalidConfigException('Controller class must extend from \\yii\\base\\Controller.');
}
return null;
}
5.分析：yii\base\Controller::runAction()
/**
* Runs an action within this controller with the specified action ID and parameters.
* If the action ID is empty, the method will use [[defaultAction]].
* @param string $id the ID of the action to be executed.
* @param array $params the parameters (name-value pairs) to be passed to the action.
* @return mixed the result of the action.
* @throws InvalidRouteException if the requested action ID cannot be resolved into an action successfully.
* @see createAction()
*/
public function runAction($id, $params = [])
{
// 创建action实例，详细见下面的代码
$action = $this->createAction($id);
if ($action === null) {
throw new InvalidRouteException('Unable to resolve the request: ' . $this->getUniqueId() . '/' . $id);
}
Yii::debug('Route to run: ' . $action->getUniqueId(), __METHOD__);
if (Yii::$app->requestedAction === null) {
Yii::$app->requestedAction = $action;
}
$oldAction = $this->action;
$this->action = $action;
$modules = [];
$runAction = true;
// 返回的modules包括该controller当前所在的module，以及该module的所有祖先module（递归直至没有祖先module）
// 然后从最初的祖先module开始，依次执行“模块级”的beforeAction()
// 如果有beforeAction()没有返回true， 那么会中断后续的执行
// call beforeAction on modules
foreach ($this->getModules() as $module) {
if ($module->beforeAction($action)) {
array_unshift($modules, $module);
} else {
$runAction = false;
break;
}
}
$result = null;
// 执行当前控制器的beforeAction，通过后再最终执行action
//（如果前面“模块级beforeAction”没有全部返回true，则这里不会执行）
if ($runAction && $this->beforeAction($action)) {
// run the action
//代码位置：yii\base\InlineAction::runWithParams()详细参考本文后续
$result = $action->runWithParams($params);
// 执行当前Controller的afterAction
$result = $this->afterAction($action, $result);
// call afterAction on modules
// 从当前模块开始，执行afterAction，直至所有祖先的afterAction
foreach ($modules as $module) {
/* @var $module Module */
$result = $module->afterAction($action, $result);
}
}
if ($oldAction !== null) {
$this->action = $oldAction;
}
// 如果有beforeAction没有通过，那么会返回null
return $result;
}
/**
* Creates an action based on the given action ID.
* The method first checks if the action ID has been declared in [[actions()]]. If so,
* it will use the configuration declared there to create the action object.
* If not, it will look for a controller method whose name is in the format of `actionXyz`
* where `xyz` is the action ID. If found, an [[InlineAction]] representing that
* method will be created and returned.
* @param string $id the action ID.
* @return Action|null the newly created action instance. Null if the ID doesn't resolve into any action.
*/
// 根据给定的动作ID创建一个动作。该方法首先检查动作ID是否已在[[actions（）]]中声明。如果是这样，它将使用在那里声明的配置来创建操作对象。如果不是，它将寻找名称为actionXyz格式的控制器方法，其中xyz是动作ID。如果找到，将创建并返回表示该方法的[[InlineAction]]。
public function createAction($id)
{
if ($id === '') {
$id = $this->defaultAction;
}
$actionMap = $this->actions();
if (isset($actionMap[$id])) {
return Yii::createObject($actionMap[$id], [$id, $this]);
}
if (preg_match('/^(?:[a-z0-9_]+-)*[a-z0-9_]+$/', $id)) {
$methodName = 'action' . str_replace(' ', '', ucwords(str_replace('-', ' ', $id)));
if (method_exists($this, $methodName)) {
$method = new \ReflectionMethod($this, $methodName);
if ($method->isPublic() && $method->getName() === $methodName) {
// InlineAction封装了将要执行的action的相关信息，该类继承自yii\base\Action
return new InlineAction($id, $this, $methodName);
}
}
}
return null;
}
6.分析： yii\web\Response::send()
/**
* Sends the response to the client.
*/
public function send()
{
if ($this->isSent) {
return;
}
// 触发事件
$this->trigger(self::EVENT_BEFORE_SEND);
// 预处理
$this->prepare();
// 触发事件
$this->trigger(self::EVENT_AFTER_PREPARE);
// 发送http响应的头部，详见下面的代码
$this->sendHeaders();
// 发送http响应的主体，详见下面的代码
$this->sendContent();
// 触发事件
$this->trigger(self::EVENT_AFTER_SEND);
$this->isSent = true;
}
请求生命周期
请求生命周期
- 用户向入口脚本
web/index.php发起请求。 - 入口脚本加载应用配置并创建一个应用 实例去处理请求。
- 应用通过请求组件解析请求的 路由。
- 应用创建一个控制器实例去处理请求。
- 控制器创建一个动作实例并针对操作执行过滤器。
- 如果任何一个过滤器返回失败，则动作取消。
- 如果所有过滤器都通过，动作将被执行。
- 动作会加载一个数据模型，或许是来自数据库。
- 动作会渲染一个视图，把数据模型提供给它。
- 渲染结果返回给响应组件。
- 响应组件发送渲染结果给用户浏览器。
静态结构
应用静态结构
每个应用都有一个入口脚本 web/index.php，这是整个应用中唯一可以访问的 PHP 脚本。 入口脚本接受一个 Web 请求并创建应用实例去处理它。 应用在它的组件辅助下解析请求， 并分派请求至 MVC 元素。视图使用小部件 去创建复杂和动态的用户界面。
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