<?php
$params = require(__DIR__ . '/params.php');
$config = [
  'id' => 'basic',
  'basePath' => dirname(__DIR__),
  'bootstrap' => ['log'],
  'components' => [
    'request' => [
      // !!! insert a secret key in the following (if it is empty) - this is required by cookie validation
      'cookieValidationKey' => 'aldjaldjaldjaljd',
    ],
    'cache' => [
      'class' => 'yii\caching\FileCache',
    ],
    'user' => [
      'identityClass' => 'app\models\User',
      'enableAutoLogin' => true,
    ],
    'errorHandler' => [
      'errorAction' => 'site/error',
    ],
    'mailer' => [
      'class' => 'yii\swiftmailer\Mailer',
      // send all mails to a file by default. You have to set
      // 'useFileTransport' to false and configure a transport
      // for the mailer to send real emails.
      'useFileTransport' => true,
    ],
    'log' => [
      'traceLevel' => YII_DEBUG ? 3 : 0,
      'targets' => [
        [
          'class' => 'yii\log\FileTarget',
          'levels' => ['error', 'warning'],
        ],
      ],
    ],
    'db' => require(__DIR__ . '/db.php'),
    'urlManager' => [
      'enablePrettyUrl' => true,
      'showScriptName' => false,
      'rules' => [
      ],
    ],
  ],
  'params' => $params,
];
if (YII_ENV_DEV) {
  // configuration adjustments for 'dev' environment
  $config['bootstrap'][] = 'debug';
  $config['modules']['debug'] = [
    'class' => 'yii\debug\Module',
  ];
  $config['bootstrap'][] = 'gii';
  $config['modules']['gii'] = [
    'class' => 'yii\gii\Module',
  ];
}
return $config;

public function actionIndex()
{
    echo \Yii::$app->id,'<br>';
    echo \Yii::$app->name,'<br>';
    exit;
    return $this->render('index',['username'=>'張三','age'=>22]);
}

#...
$config = require(__DIR__ . '/../config/web.php');
(new yii\web\Application($config))->run();