檔案路徑/framework/web/CWebApplication.php
/**
	 * Creates a controller instance based on a route.
	 * The route should contain the controller ID and the action ID.
	 * It may also contain additional GET variables. All these must be concatenated together with slashes.
	 *
	 * This method will attempt to create a controller in the following order:
	 * <ol>
	 * <li>If the first segment is found in {@link controllerMap}, the corresponding
	 * controller configuration will be used to create the controller;</li>
	 * <li>If the first segment is found to be a module ID, the corresponding module
	 * will be used to create the controller;</li>
	 * <li>Otherwise, it will search under the {@link controllerPath} to create
	 * the corresponding controller. For example, if the route is "admin/user/create",
	 * then the controller will be created using the class file "protected/controllers/admin/UserController.php".</li>
	 * </ol>
	 * @param string $route the route of the request.
	 * @param CWebModule $owner the module that the new controller will belong to. Defaults to null, meaning the application
	 * instance is the owner.
	 * @return array the controller instance and the action ID. Null if the controller class does not exist or the route is invalid.
	 * localhost:test.com/api/train/product/dosomething
	 */
	public function createController($route,$owner=null)
	{
		if($owner===null)
			$owner=$this;
		if(($route=trim($route,'/'))==='')
			$route=$owner->defaultController;
		$caseSensitive=$this->getUrlManager()->caseSensitive;

		$route.='/';
		while(($pos=strpos($route,'/'))!==false)
		{
			$id=substr($route,0,$pos);
			if(!preg_match('/^\w+$/',$id))
				return null;
			if(!$caseSensitive)
				$id=strtolower($id);
			$route=(string)substr($route,$pos+1);
			if(!isset($basePath))  // first segment
			{
				if(isset($owner->controllerMap[$id]))
				{
					return array(
						Yii::createComponent($owner->controllerMap[$id],$id,$owner===$this?null:$owner),
						$this->parseActionParams($route),
					);
				}

				if(($module=$owner->getModule($id))!==null)
					return $this->createController($route,$module);

				$basePath=$owner->getControllerPath();
				$controllerID='';
			}
			else
				$controllerID.='/';
			$className=ucfirst($id).'Controller';
			$classFile=$basePath.DIRECTORY_SEPARATOR.$className.'.php';

			if($owner->controllerNamespace!==null)
				$className=$owner->controllerNamespace.'\\'.str_replace('/','\\',$controllerID).$className;

			if(is_file($classFile))
			{
				if(!class_exists($className,false))
					require($classFile);
				if(class_exists($className,false) && is_subclass_of($className,'CController'))
				{
					$id[0]=strtolower($id[0]);
					return array(
						new $className($controllerID.$id,$owner===$this?null:$owner),
						$this->parseActionParams($route),
					);
				}
				return null;
			}
			$controllerID.=$id;
			$basePath.=DIRECTORY_SEPARATOR.$id;
		}
	}
 

我們的分析的地址比如：test.com/api/train/product/dosomething

先分析第一個引數比如api

1、會分析配置（這裡一般是main.php）沒見裡有沒有controllerMap或模組這個配置，這是配置了api這個模組，所以路徑在/modules/

2、(api)配置成了模組，這時候的路徑就是/modules/api/

3、(train)如果不是模組，就是搜尋有沒有/modules/api/controllers/trainController.php,如果沒有就是目錄，這時候的路徑是：/modules/api/train/

4、(product)就會把當前的引數，拼接成productController.php檔案，比如/modules/api/controllers/train/controllers/productController.php，這次找到這個路徑了，載入檔案

總結，所以就算你的controller放的路徑再深，路由都能找到，不用擔心，因為這是用迴圈遍歷的。