Yii2框架实现登录、退出及自动登录功能的方法详解

public function getIsGuest($checkSession = true)
{
  return $this->getIdentity($checkSession) === null;
}
public function getIdentity($checkSession = true)
{
  if ($this->_identity === false) {
   if ($checkSession) {
    $this->renewAuthStatus();
   } else {
    return null;
   }
  }
  return $this->_identity;
}

protected function renewAuthStatus()
{
  $session = Yii::$app->getSession();
  $id = $session->getHasSessionId() || $session->getIsActive() ? $session->get($this->idParam) : null;
  if ($id === null) {
   $identity = null;
  } else {
   /** @var IdentityInterface $class */
   $class = $this->identityClass;
   $identity = $class::findIdentity($id);
  }
  $this->setIdentity($identity);
  if ($this->authTimeout !== null && $identity !== null) {
   $expire = $session->get($this->authTimeoutParam);
   if ($expire !== null && $expire < time()) {
    $this->logout(false);
   } else {
    $session->set($this->authTimeoutParam, time() + $this->authTimeout);
   }
  }
  if ($this->enableAutoLogin) {
   if ($this->getIsGuest()) {
    $this->loginByCookie();
   } elseif ($this->autoRenewCookie) {
    $this->renewIdentityCookie();
   }
  }
}

protected function loginByCookie()
{
  $name = $this->identityCookie['name'];
  $value = Yii::$app->getRequest()->getCookies()->getValue($name);
  if ($value !== null) {
   $data = json_decode($value, true);
   if (count($data) === 3 && isset($data[0], $data[1], $data[2])) {
    list ($id, $authKey, $duration) = $data;
    /** @var IdentityInterface $class */
    $class = $this->identityClass;
    $identity = $class::findIdentity($id);
    if ($identity !== null && $identity->validateAuthKey($authKey)) {
     if ($this->beforeLogin($identity, true, $duration)) {
      $this->switchIdentity($identity, $this->autoRenewCookie ? $duration : 0);
      $ip = Yii::$app->getRequest()->getUserIP();
      Yii::info("User '$id' logged in from $ip via cookie.", __METHOD__);
      $this->afterLogin($identity, true, $duration);
     }
    } elseif ($identity !== null) {
     Yii::warning("Invalid auth key attempted for user '$id': $authKey", __METHOD__);
    }
   }
  }
}

$this->switchIdentity($identity, $this->autoRenewCookie ? $duration : 0);

public function logout($destroySession = true)
{
  $identity = $this->getIdentity();
  if ($identity !== null && $this->beforeLogout($identity)) {
   $this->switchIdentity(null);
   $id = $identity->getId();
   $ip = Yii::$app->getRequest()->getUserIP();
   Yii::info("User '$id' logged out from $ip.", __METHOD__);
   if ($destroySession) {
    Yii::$app->getSession()->destroy();
   }
   $this->afterLogout($identity);
  }
  return $this->getIsGuest();
}
public function switchIdentity($identity, $duration = 0)
{
  $session = Yii::$app->getSession();
  if (!YII_ENV_TEST) {
   $session->regenerateID(true);
  }
  $this->setIdentity($identity);
  $session->remove($this->idParam);
  $session->remove($this->authTimeoutParam);
  if ($identity instanceof IdentityInterface) {
   $session->set($this->idParam, $identity->getId());
   if ($this->authTimeout !== null) {
    $session->set($this->authTimeoutParam, time() + $this->authTimeout);
   }
   if ($duration > 0 && $this->enableAutoLogin) {
    $this->sendIdentityCookie($identity, $duration);
   }
  } elseif ($this->enableAutoLogin) {
   Yii::$app->getResponse()->getCookies()->remove(new Cookie($this->identityCookie));
  }
}