以上生成和解析二維碼用了兩個庫：（QRCode、QZXing）

這兩個庫可以自行下載。說一下引用，在pro中增加對應pri的路徑：

include(QRCode/QRCode.pri)
include(QZXing/QZXing.pri)

#include "../QRCode/qrencode.h"
#include "../QZXing/QZXing.h"
#include <QPixmap>
 
SCreateQRCode::SCreateQRCode(QObject *parent) : QObject(parent)
{
}
 
QPixmap SCreateQRCode::createQRCode(const QString &text)
{
    int margin = 2;
    if (text.length() == 0) {
        return QPixmap();
    }
    QRcode *qrcode = QRcode_encodeString(text.toLocal8Bit(), 2, QR_ECLEVEL_L, QR_MODE_8, 0);
    if (qrcode == NULL) {
        return QPixmap();
    }
    unsigned char *p, *q;
    p = NULL;
    q = NULL;
    int x, y, bit;
    int realwidth;
 
    realwidth = qrcode->width;
    QImage image = QImage(realwidth, realwidth, QImage::Format_Indexed8);
    QRgb value;
    value = qRgb(255,255,255);
    image.setColor(0, value);
    value = qRgb(0,0,0);
    image.setColor(1, value);
    image.setColor(2, value);
    image.fill(0);
    p = qrcode->data;
    for(y=0; y<qrcode->width; y++) {
        bit = 7;
        q += margin / 8;
        bit = 7 - (margin % 8);
        for(x=0; x<qrcode->width; x++) {
            if ((*p & 1) << bit)
                image.setPixel(x, y, 1);
            else
                image.setPixel(x, y, 0);
            bit--;
            if(bit < 0) {
                q++;
                bit = 7;
            }
            p++;
        }
    }
    return QPixmap::fromImage(image.scaledToWidth(200));
}
 
#include <QDebug>
QString SCreateQRCode::readQRPicture(const QString path)
{
    QZXing decoder;
    QString qrmsg = decoder.decodeImageFromFile(path);
    qDebug() << "SCreateQRCode:" << qrmsg;
    return qrmsg;
}