字符串 - PHP 敏感词违法关键字检测 算法方案

Question

已有6000条关键字，分3批次。
一批为替换 replace，一批为遇到需要审核 censor，最后一批为遇到就禁止发布banned。
设计数据表如下：

<code>mysql> desc tbl_censor;
+-------------+----------------------+------+-----+---------+----------------+
| Field       | Type                 | Null | Key | Default | Extra          |
+-------------+----------------------+------+-----+---------+----------------+
| id          | smallint(6) unsigned | NO   | PRI | NULL    | auto_increment |
| censortype  | smallint(6)          | NO   |     | 1       |                |
| find        | varchar(120)         | NO   | UNI |         |                |
| replacement | varchar(255)         | NO   |     |         |                |
| extra       | varchar(255)         | NO   |     |         |                |
| uptime      | int(11)              | YES  |     | NULL    |                |
| enable      | int(1)               | NO   |     | 1       |                |
+-------------+----------------------+------+-----+---------+----------------+
7 rows in set (0.01 sec)
</code>

由于有6000多关键字，使用 foreach 的 strstr?还是preg_match ?
追求效率，每小时提交量为10万多文章。

---

刚刚写的一种：

<code>php</code><code>namespace app\helpers;


use app\models\other\Censor;
use app\models\other\CensorLog;

class CensorHelper
{
    public $id;
    public $data;
    public $match_banned;
    public $match_censor;

    public function __construct($id = 'censor')
    {
        $this->id = $id;
        $this->match_banned = [];
        $this->match_censor = [];
        $this->data = $this->getData();
    }

    /**
     * @description 获取正则表达式
     * @return array|mixed
     */
    public function getData()
    {
        $data = \Yii::$app->cache->get($this->id);
        if (empty($data)) {
            $words = Censor::find()
                ->where(['enable' => 1])
                ->andWhere([' != ', 'replacement', ''])
                ->orderBy(['replacement' => SORT_ASC, 'find' => SORT_DESC])
                ->asArray()
                ->all();

            $censor = [];
            $banned = [];
            $replace = [];
            foreach ($words as $row) {
                switch ($row['replacement']) {
                    case '{censor}':
                        $censor[] = $row['find'];
                        break;

                    case '{banned}':
                        $banned[] = $row['find'];
                        break;

                    default:
                        $replace['from'][] = $row['replacement'];
                        $replace['to'][] = $row['find'];
                        break;
                }
            }

            if ($censor || $banned) {
                $data = [
                    'censor' => $this->generateRegularExpression($censor),
                    'banned' => $this->generateRegularExpression($banned),
                    'replace' => $replace,
                ];

                \Yii::$app->cache->set($this->id, $data);
            }
        }

        return $data;
    }

    /**
     * @describe 生成正则表达式
     * @param array $words
     * @return string
     */
    public function generateRegularExpression(array $words)
    {
        $regular = implode('|', array_map('preg_quote', $words));

        return "/$regular/i";
    }

    public function check($string)
    {
        $this->banned($string);
        $this->censor($string);
    }

    public function censor($string)
    {
        if (!empty($this->data['censor']) && preg_match($this->data['censor'], $string, $matches)) {
            $this->match_censor = array_merge($this->match_censor, $matches[0]);
        }
    }

    public function banned($string)
    {
        if (!empty($this->data['banned']) && preg_match($this->data['banned'], $string, $matches)) {
            $this->match_banned = array_merge($this->match_banned, $matches[0]);
        }
    }

    //重新加载
    public function flush()
    {
        \Yii::$app->cache->delete($this->id);
        $this->getData();
    }

    /**
     * @describe 替换
     * @param $string
     * @return mixed
     */
    public function replace($string)
    {
        return !empty($this->data['replace']) ? str_replace($this->data['replace']['from'], $this->data['replace']['to'], $string) : $string;
    }


    /**
     * @return string
     */
    public function getLevel()
    {
        if (!empty($this->match_banned)) {
            return 'banned';

        } else if (!empty($this->match_censor)) {
            return 'censor';

        } else {
            return 'pass';
        }
    }

    /**
     * @describe 添加记录
     * @param $tableId
     * @param $dataId
     */
    public function addLog($tableId, $dataId)
    {
        $log = new CensorLog();
        $log->datatb = $tableId;
        $log->dataid = $dataId;
        $log->matchcensor = implode(',', $this->match_censor);
        $log->matchbanned = implode(',', $this->match_banned);
        $log->addtime = time();

        if (!\Yii::$app->user->isGuest) {
            $log->uid = \Yii::$app->user->getId();
            $log->uname = \Yii::$app->user->getUname();
        }

        $log->ip = IpHelper::getIP();
        $log->iploc = IpHelper::getLocation($log->ip);
        $log->save();

    }
}
</code>

Answer 1

trie 树算法最适合。

PHP 关键词过滤扩展，该扩展依赖于 libdatrie（Trie 算法的 C++ 实现）。

Answer 2

你这个敏感词匹配，不需要用到正则，只用简单的匹配或者替换就行了。

关键字分成三类存memcached。

然后对文章进行匹配，应该从最严厉的banned来匹配，接着是要censor的关键字，最后才是可以replace的敏感词。

1 遇到就禁止发布 => str_pos
2 遇到需要审核 => str_pos
3 替换 => str_replace