I'm currently building a new CakePHP app with version 3.0.0-RC1, and trying to install and use the jasig/phpCAS plugin. Using this guide, I've run the following command from the command prompt: composer require jasig/phpcas
This correctly copies the jasig/phpcas files into the vendor directory of my app, but one of the other files that the guide says should be updated (vendor/cakephp-plugins.php) doesn't even exist.
I've had a tough time accessing the plugin. I want to be able to call its static methods, and I keep getting errors of the form: Error: Class 'App\Controller\phpCAS' not found. (The exact directory in the error changes depending on where I'm calling the method from.)
I don't know if this is due to not having the cakephp-plugins.php file, or if I'm not calling the plugin correctly. It's my understanding that if the plugin is loaded I should just be able to call static methods on it like this: phpCAS::methodName()
First of all jasig/phpcas is not a CakePHP plugin. And the vendor/cakephp-plugins.php file is created by the CakePHP plugin installer, so if you don't see such a file, you seem to have either not installed any plugins yet, or you are not using a recent version of the installer, as the creation of this file has been introduced just recently.
Regarding the error about the class not being found, you are missing the leading namespace separator (\phpCAS::methodName()) to access the class in the global namespace, respectively you are missing a proper import (use phpCAS;) that would make the class available in the current namespace.
In case you are not familiar with namespaces, you may want to start with: http://php.net/namespaces
来源：https://stackoverflow.com/questions/28220147/using-cakephp-3-0-plugin