c++qt中JSON读取

基础用法

#include <QJsonDocument>
#include <QJsonObject>
#include <QJsonArray>

    QString APPnameValue = "";
    QString DeviceID = "";
    QString BatteryID = "";

void DetectionWorker::readJson(const QString &filePath)
{
    QFile file(filePath);
    if (!file.open(QIODevice::ReadOnly)) {
        qWarning() << "Could not open file for reading:" << file.errorString();
        return;
    }

    QByteArray jsonData = file.readAll();
    file.close();

    QJsonDocument jsonDoc = QJsonDocument::fromJson(jsonData);
    if (jsonDoc.isNull()) {
        qWarning() << "Failed to create JSON doc.";
        return;
    }

    if (!jsonDoc.isObject()) {
        qWarning() << "JSON is not an object.";
        return;
    }

    QJsonObject jsonObj = jsonDoc.object();

    // 读取 "Appname" 键的值
    if (jsonObj.contains("Appname")) {
        APPnameValue = jsonObj.value("Appname").toString();
        qDebug() << "Value for 'Appname':" << APPnameValue;
    } else {
        qWarning() << "'Appname' key not found in JSON.";
    }

    // 读取 "DeviceID" 键的值
    if (jsonObj.contains("DeviceID")) {
        DeviceID = jsonObj.value("DeviceID").toString();
        qDebug() << "Value for 'DeviceID':" << DeviceID;
    } else {
        qWarning() << "'DeviceID' key not found in JSON.";
    }

    // 读取 "BatteryID" 键的值
    if (jsonObj.contains("BatteryID")) {
        BatteryID = jsonObj.value("BatteryID").toString();
        qDebug() << "Value for 'BatteryID':" << BatteryID;
    } else {
        qWarning() << "'BatteryID' key not found in JSON.";
    }

}

进阶用法

    QString APPnameValue = "";
    QString DeviceID = "";
    QString siteCode = "";
    QString equipNum = "";
    QString productType = "";
    QString userName = "";
    QString qualityStatus = "";
    QString completeQty = "";
    QString testOrderNum = "";

void OnlineFrameViewModel::readJson(const QString &filePath)
{
    QFile file(filePath);
    if (!file.open(QIODevice::ReadOnly)) {
        qWarning() << "Could not open file for reading:" << file.errorString();
        return;
    }

    QJsonDocument jsonDoc = QJsonDocument::fromJson(file.readAll());
    file.close();

    if (jsonDoc.isNull() || !jsonDoc.isObject()) {
        qWarning() << "Invalid JSON document or not an object";
        return;
    }

    QJsonObject jsonObj = jsonDoc.object();

    // 字段映射表
    const QVector<QPair<QString, QString&>> fields = {
        {"APPnameValue", APPnameValue},
        {"DeviceID", DeviceID},
        {"siteCode", siteCode},
        {"equipNum", equipNum},
        {"productType", productType},
        {"userName", userName},
        {"qualityStatus", qualityStatus},
        {"completeQty", completeQty},
        {"testOrderNum", testOrderNum}
    };

    // 处理每个字段
    for (const auto& field : fields) {
        const QString& key = field.first;
        QString& target = field.second;

        if (jsonObj.contains(key)) {
            target = jsonObj.value(key).toString();
            qDebug() << "Value for '" << key << "':" << target;
        } else {
            qWarning() << "'" << key << "' key not found in JSON.";
        }
    }
}