[emoji]字符串处理

1、修改数据库的字符支持，utf8==>utf8mb4

2、匹配出emoji表情，替换与还原

    /**
     * 表情转换  更新到ios9.2涵盖编码范围
     * @param $str
     * @return mixed
     */  
    public static function emoji_to_html($str) {  
        $regex = ‘/([0-9|#][\x{20E3}])|[\x{00ae}|\x{00a9}|\x{203C}|\x{2047}|\x{2048}|\x{2049}|\x{3030}|\x{303D}|\x{2139}|\x{2122}|\x{3297}|\x{3299}][\x{FE00}-\x{FEFF}]?|[\x{2190}-\x{21FF}][\x{FE00}-\x{FEFF}]?|[\x{2300}-\x{23FF}][\x{FE00}-\x{FEFF}]?|[\x{2460}-\x{24FF}][\x{FE00}-\x{FEFF}]?|[\x{25A0}-\x{25FF}][\x{FE00}-\x{FEFF}]?|[\x{2600}-\x{27BF}][\x{FE00}-\x{FEFF}]?|[\x{2900}-\x{297F}][\x{FE00}-\x{FEFF}]?|[\x{2B00}-\x{2BF0}][\x{FE00}-\x{FEFF}]?|[\x{1F000}-\x{1F6FF}][\x{FE00}-\x{FEFF}]?|[\x{1F900}-\x{1F9FF}][\x{FE00}-\x{FEFF}]?/u‘;  
        $str = preg_replace_callback($regex,function($matches){  
            $str = json_encode($matches[0]);  
            $str = ‘<em data-emoji=‘ . str_replace(‘\u‘, ‘em:‘, $str) . ‘></em>‘;  
            return $str;  
        },$str);  
        return $str;  
    }  
    从数据库取出后再转回  
    $string = preg_replace_callback(‘/<em data-emoji=\"(.*?)\"><\/em>/is‘, "self::preg_emoji", $string);  
    /**
     * 输出emoji表情
     * @param $matches
     * @return mixed
     */  
    public static function preg_emoji($matches)  
    {  
        $str = $matches[0];  
        $str = str_replace(‘em:‘, ‘\u‘, $str);  
        return $str;  
    }

3、直接过滤emoji表情

     /**
     * 过滤表情
     * @param $str
     * @return mixed
     */  
    public static function filter_emoji($str) {  
        $regex = ‘/(\\\u[ed][0-9a-f]{3})/i‘;  
        $str = json_encode($str);  
        $str = preg_replace($regex, ‘‘, $str);  
        return json_decode($str);  
    }