42.写入XML

 1 #include <QtGui>
 2 #include <QtXml>
 3 #include <iostream>
 4 
 5 //创建一个树结构
 6 void populateTree(QTreeWidget *treeWidget)
 7 {
 8     QStringList labels;
 9     labels << QObject::tr("Terms") << QObject::tr("Pages");
10 
11     treeWidget->setHeaderLabels(labels);
12     treeWidget->header()->setResizeMode(QHeaderView::Stretch);
13     treeWidget->setWindowTitle(QObject::tr("XML Stream Writer"));
14     treeWidget->show();
15 
16     (void) new QTreeWidgetItem(treeWidget,
17             QStringList() << "sidebearings" << "10, 34-35, 307-308");
18     QTreeWidgetItem *subterm = new QTreeWidgetItem(treeWidget,
19             QStringList() << "subtraction");
20     (void) new QTreeWidgetItem(subterm,
21             QStringList() << "of pictures" << "115, 244");
22     (void) new QTreeWidgetItem(subterm,
23             QStringList() << "of vectors" << "9");
24 }
25 
26 //生成一个新的开始标签
27 void writeIndexEntry(QXmlStreamWriter *xmlWriter, QTreeWidgetItem *item)
28 {
29     //创建一个开始标签
30     xmlWriter->writeStartElement("entry");
31     //给标签添加属性
32     xmlWriter->writeAttribute("term", item->text(0));
33     //获取子树的第二个元素
34     QString pageString = item->text(1);
35     //根据','拆开
36     if (!pageString.isEmpty()) {
37         QStringList pages = pageString.split(", ");
38         //依次写入Text元素
39         foreach (QString page, pages)
40             xmlWriter->writeTextElement("page", page);
41     }
42     //如果有子项则递归调用
43     for (int i = 0; i < item->childCount(); ++i)
44         writeIndexEntry(xmlWriter, item->child(i));
45     xmlWriter->writeEndElement();
46 }
47 
48 
49 bool writeXml(const QString &fileName, QTreeWidget *treeWidget)
50 {
51     QFile file(fileName);
52     if (!file.open(QFile::WriteOnly | QFile::Text)) {
53         std::cerr << "Error: Cannot write file "
54                   << qPrintable(fileName) << ": "
55                   << qPrintable(file.errorString()) << std::endl;
56         return false;
57     }
58 
59     //写xml
60     QXmlStreamWriter xmlWriter(&file);
61     xmlWriter.setAutoFormatting(true);
62     //写首行<?xml version="1.0" encoding="UTF-8">
63     xmlWriter.writeStartDocument();
64     //生成一个开始标签
65     xmlWriter.writeStartElement("bookindex");
66     //对于每一个顶级项,调用writeIndexEntry函数
67     for (int i = 0; i < treeWidget->topLevelItemCount(); ++i)
68         writeIndexEntry(&xmlWriter, treeWidget->topLevelItem(i));
69     xmlWriter.writeEndDocument();
70 
71     file.close();
72     if (file.error()) {
73         std::cerr << "Error: Cannot write file "
74                   << qPrintable(fileName) << ": "
75                   << qPrintable(file.errorString()) << std::endl;
76         return false;
77     }
78     return true;
79 }
80 
81 int main(int argc, char *argv[])
82 {
83     QApplication app(argc, argv);
84     QTreeWidget treeWidget;
85     populateTree(&treeWidget);
86     writeXml("out1.xml", &treeWidget);
87     return app.exec();
88 }