Step1:
Make a folder named "components" in your project root folder.
step2:
write your custom component inside components folder eg:MyComponent.php
namespace app\components; use Yii; use yii\base\Component; use yii\base\InvalidConfigException; class MyComponent extends Component { public function welcome() { echo "Hello..Welcome to MyComponent"; } }
Step3:
Add your component inside the config/web.php file
‘components‘ => [ ‘mycomponent‘ => [ ‘class‘ => ‘app\components\MyComponent‘, ], ]
Step4:
You are done!. Now you can use your component method "welcome" inside any of your app controller actions. eg:controllers/TestController.php
namespace app\controllers; use Yii; class TestController extends \yii\web\Controller { public function actionWelcome() { Yii::$app->mycomponent->welcome(); } }
原文：http://www.cnblogs.com/wlemory/p/4611422.html