src/Utils/StrUtil.php
public static function characet($str, $targetCharset)
    {
        if (empty($str)) {
            return $str;
        }

        if (strcasecmp('UTF-8', $targetCharset) != 0) {
            $str = mb_convert_encoding($str, $targetCharset, 'UTF-8');
        }

        return $str;
    }
public static function characet($str, $targetCharset)
    {
        if (empty($str)) {
            return $str;
        }

        if (strcasecmp('UTF-8', $targetCharset) != 0) {
            $str = mb_convert_encoding($str, $targetCharset, 'UTF-8');
        }

        return $str;
    }
转码字符集转码  仅支持 转码 到 UTF-8
@param string $str
@param string $targetCharset
@return mixed|string