qt按照不同编码格式读取文字(UTF-16LE,UTF-8,UTF-8BOM,UTF-16BE)

enum class EncodingFormat : int
{
    ANSI = 0,//GBK
    UTF16LE,
    UTF16BE,
    UTF8,
    UTF8BOM,
};
EncodingFormat VideoPlayer::FileCharacterEncoding(const QString &fileName)
{
    //假定默认编码utf8
        EncodingFormat code = EncodingFormat::UTF8;

        QFile file(fileName);
        if (file.open(QIODevice::ReadOnly))
        {
            //读取3字节用于判断
            QByteArray buffer = file.read(3);
            quint8 sz1st = buffer.at(0);
            quint8 sz2nd = buffer.at(1);
            quint8 sz3rd = buffer.at(2);
            if (sz1st == 0xFF && sz2nd == 0xFE)
            {
                code = EncodingFormat::UTF16LE;
            }
            else if (sz1st == 0xFE && sz2nd == 0xFF)
            {
                code = EncodingFormat::UTF16BE;
            }
            else if (sz1st == 0xEF && sz2nd == 0xBB && sz3rd == 0xBF)
            {
                code = EncodingFormat::UTF8BOM;
            }
            else
            {
                //尝试用utf8转换,如果无效字符数大于0,则表示是ansi编码
                QTextCodec::ConverterState cs;
                QTextCodec* tc = QTextCodec::codecForName("utf-8");
                tc->toUnicode(buffer.constData(), buffer.size(), &cs);
                code = (cs.invalidChars > 0) ? EncodingFormat::ANSI : EncodingFormat::UTF8;
            }

            file.close();
        }

        return code;
}

上面是解析文件格式，下面是按照格式读取内容

QString srtfile = "D://test.srt";
EncodingFormat code = FileCharacterEncoding(srtfile);
    QFile file(srtfile);
    if(!file.open(QIODevice::ReadOnly)) {
        qDebug()<<"未找到外挂字幕文件："<