QT 使用XML保存操作记录

1 实现程序保存操作记录的思路

思路来源： 由于在一些绘图工具中，有些将操作的历史记录，缓存的操作配置保存在了json文件，也有的保存到了xml文件中，如下图所示。经过个人的对比发现xml的文件结构简单、文件的可读性强，节点和内容项之间关系层次清晰，能够实现简单、快速、清晰的内容缓存，非常适合做复杂数据类型的操作记录、工程操作文件记录、配置文件工具。

• json 示例(来自一个友商的算法标注工具)

{
  "version": "4.5.6",
  "flags": {},
  "shapes": [
    {
      "description": null,
      "mask": null,
      "label": "7",
      "points": [
        [
          574.5679012345677,
          630.8641975308642
        ],
        [
          701.7283950617282,
          0.0
        ],
        [
          822.7160493827159,
          193.82716049382702
        ],
        [
          1091.8518518518517,
          169.1358024691358
        ]
      ],
      "group_id": null,
      "shape_type": "polygon",
      "flags": {}
    },
    {
      "description": null,
      "mask": null,
      "label": "7",
      "points": [
        [
          970.5472636815921,
          377.96019900497504
        ],
        [
          763.2246176524784,
          204.6395798783858
        ],
        [
          689.9502487562188,
          457.0646766169153
        ],
        [
          689.9502487562188,
          639.1542288557212
        ],
        [
          882.4875621890546,
          636.1691542288554
        ],
        [
          1222.7860696517412,
          583.9303482587063
        ]
      ],
      "group_id": null,
      "shape_type": "polygon",
      "flags": {}
    },
    {
      "description": null,
      "mask": null,
      "label": "7",
      "points": [
        [
          536.8694885361556,
          394.21340388007053
        ],
        [
          596.1287477954147,
          430.01587301587324
        ]
      ],
      "group_id": null,
      "shape_type": "circle",
      "flags": {}
    }
  ],
  "imagePath": "微信图片_20231027144505.png",
  "imageData": null,
  "imageHeight": 1080,
  "imageWidth": 1920
}

• xml示例 (qdraw)
  

DOCTYPE qdraw>
<canvas width="800" height="600">
    <polyline rotate="0" x="469.004" y="326.484" z="0" width="394" height="289">
        <point x="-88.0041" y="20.5161"/>
        <point x="76.9959" y="144.516"/>
        <point x="196.996" y="65.5161"/>
        <point x="150.996" y="-144.484"/>
        <point x="-24.0041" y="-59.4839"/>
        <point x="-163.004" y="-63.4839"/>
        <point x="-197.004" y="53.5161"/>
        <point x="-116.004" y="56.5161"/>
        <point x="-150.004" y="11.5161"/>
    polyline>
    <polyline rotate="0" x="164.945" y="321.008" z="0" width="218" height="134">
        <point x="-71.9446" y="26.9924"/>
        <point x="27.0554" y="66.9924"/>
        <point x="109.055" y="8.99239"/>
        <point x="-44.9446" y="-67.0076"/>
        <point x="-108.945" y="17.9924"/>
        <point x="-70.9446" y="25.9924"/>
    polyline>
    <ellipse startAngle="40" spanAngle="400" rotate="0" x="155" y="125.5" z="0" width="174" height="125"/>
    <roundrect rx="0.1" ry="0.333333" rotate="0" x="357.5" y="461" z="0" width="141" height="108"/>
    <rect rotate="0" x="104" y="488.5" z="0" width="152" height="163"/>
canvas>

2 XML文档基本结构

3 QDomDocument实现XML读写

原理说明： 和json文件处理发方式相同。根据节点、子节点、内容项的关系生成、加载XML文件的内容。
方案缺点： 生成的xml文档中的内容项的顺序是随机的，如下图所示。需要添加随机方法处理，参见文章Qt中使用QDomDocument生成XML文件元素属性随机乱序解决办法 、解决QDomDocument的setattribute乱序，这样能保证每行顺序都是一样的，但是也和自己生成顺序不同。该方法逐渐被淘汰，请参见下文，方法2QXmlStreamWriter实现。

自己期望的结果

DOCTYPE algoConfig>
<baseConfig>
    <algolist>
        <algo algId="101001" algName="未戴安全帽" serverType="图片服务" depModel1="1030" depLable1="NO_HELMET" depModel2="" depLable2="" depModel3="" depLable3=""/>
        <algo algId="101002" algName="未穿长袖" serverType="图片服务" depModel1="1030" depLable1="PERSON" depModel2="" depLable2="" depModel3="" depLable3=""/>
algolist>
    <modelMap>
        <model modelName="1303" reName="2303"/>
    modelMap>
baseConfig>

生成的结果

DOCTYPE algoConfig>
<baseConfig>
    <algolist>
        <algo serverType="图片服务" algName="未戴安全帽" algId="101001"  depModel1="1030" depLable1="NO_HELMET" depModel2="" depLable2="" depModel3="" depLable3=""/>
        <algo serverType="图片服务" algName="未穿长袖" algId="101002"   depModel1="1030" depLable1="PERSON" depModel2="" depLable2="" depModel3="" depLable3=""/>
algolist>
    <modelMap>
        <model modelName="1303" reName="2303"/>
    modelMap>
baseConfig>

3.1 QDomDocument实现生成XML文件

方法说明： 采用QDomDocument实现，方案传统优缺点。

#include 
#include 
#include 

// Method to generate XML file
void generateXMLFile() {
    QDomDocument document;

    // Making the root element
    QDomElement root = document.createElement("baseConfig");

    // Making elements of algolist
    QDomElement algolist = document.createElement("algolist");

    QDomElement algo1 = document.createElement("algo");
    algo1.setAttribute("algId", "101001");
    algo1.setAttribute("algName", "未戴安全帽");
    algo1.setAttribute("serverType", "图片服务");
    algo1.setAttribute("depModel1", "1030");
    algo1.setAttribute("depLable1", "NO_HELMET");
    algolist.appendChild(algo1);

    QDomElement algo2 = document.createElement("algo");
    algo2.setAttribute("algId", "101002");
    algo2.setAttribute("algName", "未穿长袖");
    algo2.setAttribute("serverType", "图片服务");
    algo2.setAttribute("depModel1", "1030");
    algo2.setAttribute("depLable1", "PERSON");
    algolist.appendChild(algo2);

    root.appendChild(algolist);

    // Making elements of modelMap
    QDomElement modelMap = document.createElement("modelMap");

    QDomElement model = document.createElement("model");
    model.setAttribute("modelName", "1303");
    model.setAttribute("reName", "2303");
    modelMap.appendChild(model);

    root.appendChild(modelMap);

    document.appendChild(root);

    // Writing to a file
    QFile file("Config.xml");
    if(!file.open(QIODevice::WriteOnly | QIODevice::Text)) {
        qDebug() << "Failed to open file for writing.";
        return;
    } else {
        QTextStream stream(&file);
        stream << document.toString();
        file.close();
        qDebug() << "File written.";
    }
}

3.2 QDomDocument实现读取XML文件

#include 
void loadXMLFile() {
    QDomDocument document;
    QFile file("Config.xml");

    if(!file.open(QIODevice::ReadOnly | QIODevice::Text)) {
        qDebug() << "Failed to open file for reading.";
        return;
    } else {
        if(!document.setContent(&file)) {
            qDebug() << "Failed to load document.";
            return;
        }
        file.close();
    }

    QDomElement root = document.firstChildElement();

    QDomNodeList algos = root.firstChildElement("algolist").elementsByTagName("algo");
    for(int i = 0; i < algos.count(); i++) {
        QDomNode algoNode = algos.at(i);
        if(algoNode.isElement()) {
            QDomElement algo = algoNode.toElement();
            qDebug() << "Algo ID: " << algo.attribute("algId");
            qDebug() << "Algo Name: " << algo.attribute("algName");
        }
    }

    QDomNodeList models = root.firstChildElement("modelMap").elementsByTagName("model");
    for(int i = 0; i < models.count(); i++) {
        QDomNode modelNode = models.at(i);
        if(modelNode.isElement()) {
            QDomElement model = modelNode.toElement();
            qDebug() << "Model Name: " << model.attribute("modelName");
            qDebug() << "Renamed as: " << model.attribute("reName");
        }
    }
}

4 QXmlStreamWriter实现读写

• 使用QXmlStreamWriter方法，读写超级简单，实现容易快速。

4.1 QXmlStreamWriter实现生成XML

#include 
void genConfForm::genXmlFile()
{
    QFile file("conf.xml");
    if (!file.open(QIODevice::WriteOnly | QIODevice::Text)) {
        qDebug() << "Failed to open file for writing.";
        return;
    }

    QXmlStreamWriter xmlWriter(&file);
    xmlWriter.setAutoFormatting(true);
    xmlWriter.writeStartDocument();
    xmlWriter.writeDTD("");
    xmlWriter.writeStartElement("baseConfig");

    xmlWriter.writeStartElement("algolist");

    int rows = ui->tableView_gc->model()->rowCount();
    for(int r = 0; r < rows; r++)
    {
        /*|0算法ID|1算法名称|2服务类型|3依赖模型1|4依赖label1|5依赖模型2|6依赖label2|7依赖模型3|8依赖label3|*/
        QString algId = ui->tableView_gc->model()->index(r,0).data().toString();
        QString algName = ui->tableView_gc->model()->index(r,1).data().toString();
        QString serverType = ui->tableView_gc->model()->index(r,2).data().toString();
        QString depModel1 = ui->tableView_gc->model()->index(r,3).data().toString();
        QString depLabel1 = ui->tableView_gc->model()->index(r,4).data().toString();
        QString depModel2 = ui->tableView_gc->model()->index(r,5).data().toString();
        QString depLabel2 = ui->tableView_gc->model()->index(r,6).data().toString();
        QString depModel3 = ui->tableView_gc->model()->index(r,7).data().toString();
        QString depLabel3 = ui->tableView_gc->model()->index(r,8).data().toString();

        xmlWriter.writeEmptyElement("algo");
        xmlWriter.writeAttribute("algId", algId);
        xmlWriter.writeAttribute("algName", algName);
        xmlWriter.writeAttribute("serverType", serverType);
        xmlWriter.writeAttribute("depModel1", depModel1);
        xmlWriter.writeAttribute("depLable1", depLabel1);
        xmlWriter.writeAttribute("depModel2", depModel2);
        xmlWriter.writeAttribute("depLable2", depLabel2);
        xmlWriter.writeAttribute("depModel3", depModel3);
        xmlWriter.writeAttribute("depLable3", depLabel3);
    }

    xmlWriter.writeEndElement();//algolist

    xmlWriter.writeStartElement("modelMap");

    for(auto& model:m_modelRename)
    {
        //第一次修改后的值，第二次修改前的值
        auto& modName = model.first;
        auto& reName = model.second;

        xmlWriter.writeEmptyElement("model");
        xmlWriter.writeAttribute("modelName", modName);
        xmlWriter.writeAttribute("reName", reName);
    }
    xmlWriter.writeEndElement();//modelMap

    xmlWriter.writeEndElement(); // baseConfig
    xmlWriter.writeEndDocument();

    file.close();
    qDebug() << "XML file generated successfully.";
}

4.2 QXmlStreamWriter实现读取XML

#include 
struct DepAllModelInfo{
    QString m_model1;
    QString m_label1;
    QString m_model2;
    QString m_label2;
    QString m_model3;
    QString m_label3;
};
using depModel = std::vector<DepModelInfo>;
struct algInfo{
    QString m_alg_name;
    QString m_server_type;
    DepAllModelInfo m_dep_model;
};
using algFullCapacity = std::map<QString,algInfo>;
/*以上是读取config.xml文件结构在程序中的数据结构*/
void genConfForm::loadXmlFile()
{
    algFullCapacity afc;
    QFile file("config.xml");
    if (!file.open(QIODevice::ReadOnly | QIODevice::Text)) {
        qDebug() << "Failed to open file for reading.";
        return;
    }

    QXmlStreamReader xmlReader(&file);

    while (!xmlReader.atEnd() && !xmlReader.hasError()) {
        // Read next element
        QXmlStreamReader::TokenType token = xmlReader.readNext();
        // If token is just StartDocument, we'll go to next
        if (token == QXmlStreamReader::StartDocument) {
            continue;
        }
        // If token is StartElement - read it
        if (token == QXmlStreamReader::StartElement)
        {
            if (xmlReader.name() == "algo")
            {
                DepAllModelInfo dam;
                QXmlStreamAttributes attributes = xmlReader.attributes();
                QString algId = attributes.value("algId").toString();
                QString algName = attributes.value("algName").toString();
                QString serverType = attributes.value("serverType").toString();
                dam.m_model1 = attributes.value("depModel1").toString();
                dam.m_label1 = attributes.value("depLable1").toString();
                dam.m_model2 = attributes.value("depModel2").toString();
                dam.m_label2 = attributes.value("depLable2").toString();
                dam.m_model3 = attributes.value("depModel3").toString();
                dam.m_label3 = attributes.value("depLable3").toString();

                if(!algId.isEmpty() && !algName.isEmpty())
                {
                    afc.insert(std::pair<QString,algInfo>(algId, {algName,serverType,dam}));
                }
            }
            if (xmlReader.name() == "model")
            {
                QXmlStreamAttributes attributes = xmlReader.attributes();
                QString dbModelName = attributes.value("modelName").toString();
                QString modifyName = attributes.value("reName").toString();
                m_modelRename.insert(std::pair<QString,QString>(dbModelName,modifyName));
            }
        }
    }

    if(!afc.empty())
        slotAlgInfo(afc);

    if (xmlReader.hasError()) {
        qDebug() << "XML error: " << xmlReader.errorString();
    }

    file.close();
}