qtreewidget 显示保存xml文件

 此文是读取和存储已知结构的xml，对于未知结构的xml，可以用递归方法读取和遍历。可参考文章：Qt遍历不规则树的节点。

1、QTreewidget设置

 //折叠图标（三角图标）换成自定义图标
	ui->treeWidget->setStyleSheet("QTreeView::branch:has-children:!has-siblings:closed,\
									 QTreeView::branch:closed:has-children:has-siblings{border-image: none; image: url(:/images/plus.png);}\
									 QTreeView::branch:open:has-children:!has-siblings,\
									 QTreeView::branch:open:has-children:has-siblings{border-image: none; image: url(:/images/minus.png);}");

2、显示保存xml

头文件

#ifndef PROCESSDEVICEXML_H
#define PROCESSDEVICEXML_H

#include <QObject>
#include <QDomElement>
#include <QTreeWidget>
#include "public.h"

#define ManageDeviceStr "ManageDevice"
#define SystemStr       "System"
#define SubSystemStr    "SubSystem"
#define DeviceStr       "Device"
#define NameStr         "name"
#define TypeStr         "type"
#define DeviceXmlName   "DeviceItem.xml"

class ProcessDeviceXml : public QObject
{
    Q_OBJECT

public:
    explicit ProcessDeviceXml(QObject *parent = nullptr);

    bool OpenXml(QString fileName, QList<DeviceInfo>& listDev, QTreeWidget* pTreeWg = NULL);
    void ShowXml(QDomElement &docElem, QList<DeviceInfo> &listDev, QTreeWidget *treeWg);
     bool SaveXML(QString fileName, QTreeWidget *pTreeWg);

    bool AddTreeItem(QTreeWidget *pTreeWg, QTreeWidgetItem *clickedItem, int itemType);
    bool delTreeItem(QTreeWidget *pTreeWg, QTreeWidgetItem *clickedItem, int nType);
signals:

public slots:

private:

};

#endif // PROCESSDEVICEXML_H

　　源文件：

显示图标时，要换成自己的图标路径；如果出现编译不通过，需要根据情况修改一下。

#include "processdevicexml.h"
#include <QTextStream>
#include <QMessageBox>
#include <QFile>
#include <QDebug>
#include "public.h"
#include "adddevicedlg.h"
#include "extern.h"

ProcessDeviceXml::ProcessDeviceXml(QObject *parent) : QObject(parent)
{

}

bool ProcessDeviceXml::OpenXml(QString fileName, QList<DeviceInfo>& listDeviceName, QTreeWidget* pTreeWg)
{
    QFile file(fileName);
    if (file.open(QIODevice::ReadOnly))
    {
        QDomDocument dom;
        QString errorStr;
        int errorLine;
        int errorCol;
        if (!dom.setContent(&file, true, &errorStr, &errorLine, &errorCol))
        {
            qDebug() << errorStr << "line: " << errorLine << "col: " << errorCol;
            file.close();
            return  false;
        }
        else
        {
            pTreeWg->clear();
            QDomElement docElem = dom.documentElement();
            ShowXml(docElem, listDeviceName, pTreeWg);
            pTreeWg->expandAll();
        }
        file.close();
        return true;
    }
    else {
        file.close();
        return false;
    }

}

void ProcessDeviceXml::ShowXml(QDomElement& docElem, QList<DeviceInfo>& listDev, QTreeWidget* treeWg)
{
    //根节点
    QTreeWidgetItem *projectItem = new QTreeWidgetItem(treeWg);
    QString projectName = docElem.attribute(NameStr);
    projectItem->setText(0, projectName);
    projectItem->setData(0, Qt::UserRole, QString::number(TypeProject));
    projectItem->setIcon(0, QIcon(QStringLiteral(":/image/system.png")));
    projectItem->setWhatsThis(0, SystemStr);

    listDev.clear();

    QDomNode systemNode = docElem.firstChild();
    while (!systemNode.isNull())
    {
        DeviceInfo devInfo;
        devInfo.listDevName.clear();
        QDomElement elementSystem = systemNode.toElement(); // try to convert the node to an element.
        if (elementSystem.tagName() == QStringLiteral(SystemStr))
        {
            QTreeWidgetItem *systemItem = new QTreeWidgetItem(projectItem);
            //系统节点
            QString strSystemName = elementSystem.attribute(NameStr);
            devInfo.qstrSystemName = strSystemName;
            systemItem->setText(0, strSystemName);
            systemItem->setData(0, Qt::UserRole, QString::number(TypeSystem));
            systemItem->setIcon(0, QIcon(QStringLiteral(":/image/system.png")));
            systemItem->setWhatsThis(0, SystemStr);

            //子系统节点
            QDomNode subsystemNode = systemNode.firstChild();
            while (!subsystemNode.isNull())
            {
                QDomElement elementDev = subsystemNode.toElement();
                if (elementDev.tagName() == QStringLiteral(SubSystemStr))
                {
                    QString strDevName = elementDev.attribute(NameStr);

                    QTreeWidgetItem *subsystemItem = new QTreeWidgetItem(systemItem);
                    subsystemItem->setText(0, strDevName);
                    subsystemItem->setIcon(0, QIcon(QStringLiteral(":/image/subSystem.png")));
                    subsystemItem->setData(0, Qt::UserRole, QString::number(TypeSubsystem));
                    subsystemItem->setWhatsThis(0, SubSystemStr);
                  

                    QDomNode devNode = subsystemNode.firstChild();
                    while (!devNode.isNull())
                    {
                        QDomElement elementDev = devNode.toElement();
                        if (elementDev.tagName() == QStringLiteral(DeviceStr))
                        {
                            QString strDevName = elementDev.attribute(NameStr);
                            QTreeWidgetItem *devItem = new QTreeWidgetItem(subsystemItem);
                            devItem->setText(0, strDevName);
                            devItem->setIcon(0, QIcon(QStringLiteral(":/Qimage/device.png")));
                            devItem->setWhatsThis(0, DeviceStr);
                            devItem->setData(0, Qt::UserRole, QString::number(TypeDevice));
                            devInfo.listDevName.push_back(strDevName);
                        }
                        devNode = devNode.nextSibling();
                    }
                }
                subsystemNode = subsystemNode.nextSibling();
            }
        }
        //下一个分组节点
        listDev.push_back(devInfo);
        systemNode = systemNode.nextSibling();
    }

    return;
}

bool ProcessDeviceXml::SaveXML(QString fileName, QTreeWidget* pTreeWg)
{
    QTreeWidgetItem *rootItem = pTreeWg->invisibleRootItem(); //树的根节点
    int countSystem = rootItem->childCount();
    if (countSystem <= 0)  //列表树没有项
    {
        return false;
    }

    QFile db(fileName);
    if (!db.open(QIODevice::WriteOnly | QIODevice::Truncate)) return false;

    //只写方式打开，并清空以前的信息
    QDomDocument doc;
    QDomProcessingInstruction instruction;
    instruction = doc.createProcessingInstruction("xml", "version=\"1.0\" encoding=\"UTF-8\"");
    doc.appendChild(instruction);

    QDomElement root = doc.createElement(ManageDeviceStr);
    QString projectName = p_globalObject->getProjectName();
    QDomAttr elementProjAttr = doc.createAttribute(NameStr);
    elementProjAttr.setValue(projectName);
    root.setAttributeNode(elementProjAttr);
    doc.appendChild(root); //添加根元素

    QTreeWidgetItem* projectItem = rootItem->child(0);
    countSystem = projectItem->childCount();
    for (int i = 0; i < countSystem; i++)
    {
        QTreeWidgetItem *systemItem = projectItem->child(i);
        QString systemName = systemItem->text(0);
        QDomElement elementSystem = doc.createElement(SystemStr);
        QDomAttr elementSystemAttr = doc.createAttribute(NameStr);
        elementSystemAttr.setValue(systemName);
        elementSystem.setAttributeNode(elementSystemAttr);
        root.appendChild(elementSystem);

        int countSubsystem = systemItem->childCount();
        for (int j = 0; j < countSubsystem; j++)
        {
            QTreeWidgetItem *subsystemItem = systemItem->child(j);
            QDomElement elementSubsystem = doc.createElement(SubSystemStr);

            //子系统项属性name
            QString subsystemName = subsystemItem->text(0);
            QDomAttr elementSubsystemNameAttr = doc.createAttribute(NameStr);
            elementSubsystemNameAttr.setValue(subsystemName);
            elementSubsystem.setAttributeNode(elementSubsystemNameAttr);

            elementSystem.appendChild(elementSubsystem);

            int coutDev = subsystemItem->childCount();
            for (int k = 0; k < coutDev; k++)
            {
                QTreeWidgetItem *devItem = subsystemItem->child(k);
                QString devName = devItem->text(0);
                QDomElement elementChn = doc.createElement(DeviceStr);
                QDomAttr elementChnAttr = doc.createAttribute(NameStr);
                elementChnAttr.setValue(devName);
                elementChn.setAttributeNode(elementChnAttr);
                elementSubsystem.appendChild(elementChn);
            }
        }
    }

    QTextStream out(&db);
    out.setCodec("UTF-8");
    doc.save(out, 4);
    db.close();

    return true;
}

bool ProcessDeviceXml::AddTreeItem(QTreeWidget* pTreeWg, QTreeWidgetItem* clickedItem, int itemType)
{
    QString qstrCaption;
    int nType = TypeDevice;
    switch (itemType) {
    case TypeProject://添加系统
        qstrCaption = "添加系统";
        nType = TypeSystem;
        break;
    case TypeSystem://添加分系统
        qstrCaption = "添加子系统";
        nType = TypeSubsystem;
        break;
    case TypeSubsystem://添加设备
    case TypeDevice:
        qstrCaption = "添加设备";
        nType = TypeDevice;
        break;
    default:
        break;
    }

    AddDeviceDlg dlg;
    dlg.SetCaption(qstrCaption);

    if(dlg.exec() == QDialog::Rejected){
        return false;
    }

    QString txt = dlg.GetTxt();
    QTreeWidgetItem *item = new QTreeWidgetItem(clickedItem);
    item->setText(0, txt);
    item->setData(0, Qt::UserRole, QString::number(nType));
    item->setIcon(0, QIcon(QStringLiteral(":image/group.png")));
    item->setWhatsThis(0, qstrCaption);

    pTreeWg->expandItem(clickedItem);

    return true;
}