Qt读写XML文档示例程序

#include "xmldemo.h" #include <Qfile> #include <QDomDocument> #include <QTextStream> #include <QMessageBox> #include <qDebug> #if defined(_MSC_VER) && (_MSC_VER >= 1600) # pragma execution_character_set("utf-8") #endif xmlDemo::xmlDemo(QWidget *parent) : QMainWindow(parent) { ui.setupUi(this); QFile file("my.xml"); if (!file.open(QIODevice::WriteOnly | QIODevice::Truncate)) return; QDomDocument doc; //dom树 QDomProcessingInstruction instruction; instruction = doc.createProcessingInstruction("xml","version=\"1.0\"encoding=\"utf-8\""); doc.appendChild(instruction); QDomElement root = doc.createElement(tr("library")); doc.appendChild(root); //添加根元素 //添加第一个book元素及其子元素 QDomElement book = doc.createElement(tr("book")); QDomAttr id = doc.createAttribute(tr("id")); id.setValue(tr("1")); book.setAttributeNode(id); QDomElement title = doc.createElement(tr("title")); QDomText text; text = doc.createTextNode(tr("Qt")); title.appendChild(text); QDomElement author = doc.createElement(tr("author")); text = doc.createTextNode(tr("石明")); author.appendChild(text); book.appendChild(title); book.appendChild(author); root.appendChild(book); // 添加第二个book元素及其子元素 book = doc.createElement(tr("book")); id = doc.createAttribute(tr("id")); id.setValue(tr("2")); book.setAttributeNode(id); title = doc.createElement(tr("title")); text = doc.createTextNode(tr("Linux")); title.appendChild(text); author = doc.createElement(tr("author")); text = doc.createTextNode(tr("亚飞")); author.appendChild(text); book.appendChild(title); book.appendChild(author); root.appendChild(book); QTextStream out(&file); doc.save(out, 4, QDomNode::EncodingFromTextStream); // 将文档保存到文件，4为子元素缩进字符数 file.close(); } xmlDemo::~xmlDemo() { } void xmlDemo::on_pBtnShowAll_clicked() { ui.listWidget->clear(); ui.listWidget->clear(); QFile file("my.xml"); if (!file.open(QIODevice::ReadOnly)) return; QDomDocument doc; if (!doc.setContent(&file)) { file.close(); return; } file.close(); //返回根节点及其子节点的元素标记名 QDomElement docElem = doc.documentElement(); //返回根元素 //qDebug() << docElem.tagName(); //library QDomNode n = docElem.firstChild(); //返回根节点的第一个子节点 while (!n.isNull()) //如果节点不为空 { if (n.isElement()) //如果节点是元素 { QDomElement e = n.toElement(); //转换为元素 ui.listWidget->addItem(e.tagName()); QDomNodeList list = e.childNodes(); for (int i = 0; i < list.count(); i++) { QDomNode node = list.at(i); qDebug() << node.toElement().tagName() + ":" + node.toElement().text(); if (node.isElement()) ui.listWidget->addItem(" " + node.toElement().tagName() + ":" + node.toElement().text()); } } n = n.nextSibling(); //下一个兄弟节点 } } //添加节点 void xmlDemo::on_pBtnAdd_clicked() { ui.listWidget->clear(); QString addTitle = ui.lEditBook->text(); QString addAuthor = ui.lEditAuthor->text(); if (addTitle == "" || addAuthor == "") { QMessageBox::information(NULL, "提示", "书名和作者不能为空"); return; } QFile file("my.xml"); if (!file.open(QIODevice::ReadOnly)) return; QDomDocument doc; if (!doc.setContent(&file)) { file.close(); return; } file.close(); QDomElement root = doc.documentElement(); QDomElement book = doc.createElement("book"); QDomAttr id = doc.createAttribute("id"); QDomElement title = doc.createElement("title"); QDomElement author = doc.createElement("Author"); QDomText text; //获得最后一个孩子节点的编号，然后+1，得到新编号 QString num = root.lastChild().toElement().attribute("id"); int count = num.toInt() + 1; id.setValue(QString::number(count)); book.setAttributeNode(id); text = doc.createTextNode(ui.lEditBook->text()); title.appendChild(text); text = doc.createTextNode(ui.lEditAuthor->text()); author.appendChild(text); book.appendChild(title); book.appendChild(author); root.appendChild(book); if (!file.open(QIODevice::WriteOnly | QIODevice::Truncate)) return; QTextStream out(&file); doc.save(out,4); file.close(); ui.listWidget->clear(); ui.listWidget->addItem("添加成功"); } void xmlDemo::doXml(const QString operate) { ui.listWidget->clear(); QFile file("my.xml"); if (!file.open(QIODevice::ReadOnly)) return; QDomDocument doc; if (!doc.setContent(&file)) { file.close(); return; } file.close(); QDomNodeList list = doc.elementsByTagName("book"); //以标签名进行查找 for (int i = 0; i < list.count(); i++) { QDomElement e = list.at(i).toElement(); if (e.attribute("id") == ui.lEditNum->text()) { if (operate == "delete") { QDomElement root = doc.documentElement(); //取出根节点 root.removeChild(list.at(i)); //从根节点删除该节点 QFile file("my.xml"); if (!file.open(QIODevice::WriteOnly | QIODevice::Truncate)) return; QTextStream out(&file); doc.save(out, 4); file.close(); ui.listWidget->addItem("删除成功"); } else if (operate == "update") { QDomNodeList child = list.at(i).childNodes(); //找到它的所有子节点，就是书名和作者 child.at(0).toElement().firstChild().setNodeValue(ui.lEditBook->text()); child.at(1).toElement().firstChild().setNodeValue(ui.lEditAuthor->text()); QFile file("my.xml"); if (!file.open(QIODevice::WriteOnly | QIODevice::Truncate)) return; QTextStream out(&file); doc.save(out, 4); file.close(); ui.listWidget->addItem("更新成功"); } else if (operate == "find") { QDomNodeList list = e.childNodes(); for (int i = 0; i < list.count(); i++) { QDomNode node = list.at(i); if (node.isElement()) ui.listWidget->addItem(" " + node.toElement().tagName() + ":" + node.toElement().text()); } } } } } void xmlDemo::on_pBtnSearch_clicked() { doXml("find"); } void xmlDemo::on_pBtnUpdate_clicked() { doXml("update"); } void xmlDemo::on_pBtnDelete_clicked() { doXml("delete"); }