用户授权

因为自己的网站不需要用户授权，所以在 config/web.php 的配置文件中 把 user 组件给去掉，还要吧  views/layouts/main.php文件里面的相关代码给去掉，在显示页面的时候会提示错误：

An Error occurred while handling another error:exception 'yii\base\InvalidConfigException' with message 'User::identityClass must be set.' in /yii2/2.0.9/yiisoft/yii2/web/User.php:163

echo Nav::widget([        'options' => ['class' => 'navbar-nav navbar-right'],        'items' => [            ['label' => 'Home', 'url' => ['/site/index']],            ['label' => 'About', 'url' => ['/site/about']],            ['label' => 'Contact', 'url' => ['/site/contact']],        ],    ]);

去掉 有关  app->user 相关的代码。

使用MemCache问题

由于之前的工程使用yii1 里面的memcache， 新工程同样需要使用缓存，也就使用了MemCache. 发现新工程里面无法访问旧工程设置的缓存内容，反之亦然。配置的memcache是同一个。最后通过比较代码，发现yii1中CCache.php 和 yii2中 Cache.php 文件中生成缓存key的规则发生了变化。代码如下：

Yii1  CCache.php

/**	 * @param string $key a key identifying a value to be cached	 * @return string a key generated from the provided key which ensures the uniqueness across applications	 */	protected function generateUniqueKey($key)	{		return $this->hashKey ? md5($this->keyPrefix.$key) : $this->keyPrefix.$key;	}

Yii2 Cache.php

/**     * Builds a normalized cache key from a given key.     *     * If the given key is a string containing alphanumeric characters only and no more than 32 characters,     * then the key will be returned back prefixed with [[keyPrefix]]. Otherwise, a normalized key     * is generated by serializing the given key, applying MD5 hashing, and prefixing with [[keyPrefix]].     *     * @param mixed $key the key to be normalized     * @return string the generated cache key     */    public function buildKey($key)    {        if (is_string($key)) {            $key = ctype_alnum($key) && StringHelper::byteLength($key) <= 32 ? $key : md5($key);        } else {            $key = md5(json_encode($key));        }        return $this->keyPrefix . $key;    }