Qt源码分析--QSettings

最新推荐文章于 2024-05-03 15:42:52 发布

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最新推荐文章于 2024-05-03 15:42:52 发布 · 1.3k 阅读

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#qt #开发语言

本文详细介绍了Qt中的QSettings类，该类用于实现跨平台的应用程序设置存储。文章深入探讨了其构造函数、setValue方法及value方法的工作原理，并展示了如何通过这些方法来读写配置。

定义：

QSettings 类提供与平台无关的持久应用程序设置。

官方例子：

QSettings settings("MySoft", "Star Runner");

settings.setValue("editor/wrapMargin", 68);

int margin = settings.value("editor/wrapMargin").toInt();

1.构造函数

QSettings::QSettings(const QString &organization, const QString &application, QObject *parent)
    : QObject(*QSettingsPrivate::create(NativeFormat, UserScope, organization, application),
              parent)
{
}


QSettingsPrivate *QSettingsPrivate::create(QSettings::Format format, QSettings::Scope scope,
                                           const QString &organization, const QString &application)
{
    return new QConfFileSettingsPrivate(format, scope, organization, application);
}

QConfFileSettingsPrivate::QConfFileSettingsPrivate(QSettings::Format format,
                                                   QSettings::Scope scope,
                                                   const QString &organization,
                                                   const QString &application)
    : QSettingsPrivate(format, scope, organization, application),
      nextPosition(0x40000000) // big positive number
{
    initFormat();
    QString org = organization;
    if (org.isEmpty()) {
        setStatus(QSettings::AccessError);
        org = QLatin1String("Unknown Organization");
    }
    QString appFile = org + QDir::separator() + application + extension;
    QString orgFile = org + extension;
    if (scope == QSettings::UserScope) {
        Path userPath = getPath(format, QSettings::UserScope);
        if (!application.isEmpty())
            confFiles.append(QConfFile::fromName(userPath.path + appFile, true));
        confFiles.append(QConfFile::fromName(userPath.path + orgFile, true));
    }
    Path systemPath = getPath(format, QSettings::SystemScope);
#if defined(Q_XDG_PLATFORM) && !defined(QT_NO_STANDARDPATHS)
    // check if the systemPath wasn't overridden by QSettings::setPath()
    if (!systemPath.userDefined) {
        // Note: We can't use QStandardPaths::locateAll() as we need all the
        // possible files (not just the existing ones) and there is no way
        // to exclude user specific (XDG_CONFIG_HOME) directory from the search.
        QStringList dirs = QStandardPaths::standardLocations(QStandardPaths::GenericConfigLocation);