c++ - How do I use QXmlStreamReader to parse an XML file that contains references to other XML files?

Question

I'm attempting to parse an xml file in C++ using a QXmlStreamReader (Qt 5.5.1). I'm using the XML file to map numeric keys to corresponding image files. I've gotten it to work with a simple XML file such as:

<?xml version="1.0" encoding="UTF-8"?>
<images>
    <group1>
        <image key="1" value="image1_group1.png"/>
        <image key="2" value="image2_group1.png"/>
    </group1>
    <group2>
        <image key="1" value="image1_group2.png"/>
        <image key="2" value="image2_group2.png"/>
    </group2>
</images>

using the following code:

#include <QFile>

xml_image_mapper::xml_image_mapper(QObject* p_parent_ptr)
{
    QFile file("myfile.xml");
    file.open(QFile::ReadOnly | QFile::Text);
    QXmlStreamReader stream_reader(&file);
    stream_reader.readNextStartElement();
    while (stream_reader.readNextStartElement())
    {
        auto* inner_map_ptr = new QMap<quint32, QString>();
        m_image_map.insert(stream_reader.name().toString(), inner_map_ptr);
        parse_xml(stream_reader, *inner_map_ptr);
    }
}

void xml_image_mapper::parse_xml(QXmlStreamReader& stream_reader, QMap<quint32, QString>& p_map)
{
    while (stream_reader.readNextStartElement())
    {
        static const QString key_name = "key";
        static const QString value_name = "value";
        quint32 key;
        QString value;
        foreach (const QXmlStreamAttribute attribute, stream_reader.attributes())
        {
            if (key_name == attribute.name())
                key = attribute.value().toInt();
            else if (value_name == attribute.name())
                value = attribute.value().toString();
            p_map.insert(key, value);
        }
        stream_reader.skipCurrentElement();
    }
}

This code correctly creates the map from numeric keys to filenames for the simple XML shown above, but fails to work for an XML file that includes references, such as:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE doc [
<!ENTITY group1 SYSTEM "group1.xml">
<!ENTITY group2 SYSTEM "group2.xml">
]>

<images>
    <group1>
        &group1;
    </group1>
    <group2>
        &group2;
    </group2>
</images>

Where group1.xml reads:

<?xml version="1.0" encoding="UTF-8"?>

<image key="1" value="image1_group1.png"/>
<image key="2" value="image2_group1.png"/>

and group2.xml reads:

<?xml version="1.0" encoding="UTF-8"?>

<image key="1" value="image1_group2.png"/>
<image key="2" value="image2_group2.png"/>

Is there a way to parse XML files with references to other XML files using a QXmlStreamReader?

标签： c++xmlqt5.5

Answer 1

从Qt 文档：

QXmlStreamReader 是一个格式良好的 XML 1.0 解析器，它不包括外部解析实体。

所以你在这里似乎不走运。