Question

我正在处理我使用QXMLStreamReader和QXMLStreamWriter的内容，以便读取和写入文件。

但我无法找到一种可以修改XML的方法，例如考虑这个XML：

<?xml version="1.0"?>
<LAMPS>
    <LIGHT1>
        <State>statevalue</State>
        <Room>roomvalue</Room>
        <Potencial>potencialvalue</Potencial>
    </LIGHT1>
</LAMPS>

使用以下代码编写：

QFile file(filename);
file.open(QIODevice::WriteOnly);

QXmlStreamWriter xmlWriter(&file);
xmlWriter.setAutoFormatting(true);
xmlWriter.writeStartDocument();

xmlWriter.writeStartElement("LAMPS");

xmlWriter.writeStartElement("LIGHT1");
xmlWriter.writeTextElement("State", "statevalue" );
xmlWriter.writeTextElement("Room", "roomvalue");
xmlWriter.writeTextElement("Potencial", "potencialvalue");
xmlWriter.writeEndElement();
xmlWriter.writeEndElement();
file.close();

现在我想再添加一个<LIGHT1>到一个EXISTING xml文件，然后在QT中如何做到这一点？

我正在做以下事情：

     //filename = my file path
     QFile file(filename);
     file.open(QIODevice::ReadWrite);
     QXmlStreamWriter xmlWriter(&file);
     QXmlStreamReader xmlReader;
     xmlReader.setDevice(&file);
     xmlWriter.setAutoFormatting(true);
     while(!xmlReader.atEnd()){
         if(xmlReader.isStartDocument())
             xmlWriter.writeStartDocument();
         if(xmlReader.isStartElement()){
             xmlWriter.writeStartElement(xmlReader.name().toString());
             if(xmlReader.name()=="LAMPS"){
                 xmlWriter.writeStartElement("Arqam");
                 xmlWriter.writeTextElement("Arqam","Lucid Dreamer");
                 xmlWriter.writeEndElement();
             }
         }
         if(xmlReader.isEndElement())
             xmlWriter.writeEndElement();
         if(xmlReader.isEndDocument())
             xmlWriter.writeEndDocument();
         xmlReader.readNext();
         file.close();

我收到以下错误：

QIODevice::write (QFile, "/Users/arqam/Desktop/XMLGenrator/input/zzzz.xml"): device not open
QIODevice::read (QFile, "/Users/arqam/Desktop/XMLGenrator/input/zzzz.xml"): device not open

Answer 1

您可以使用#include <QXmlStreamReader> #include <QXmlStreamWriter> #include <QFile> #include <QDomElement> #include <QDomDocument> #include <QDomText> #include <QTextStream> int main() { QFile file("test.xml"); if (!file.open(QIODevice::ReadOnly | QIODevice::Text)) { qDebug() << "Failed to open file"; return 0; } QDomDocument document; if (!document.setContent(&file)) { qDebug() << "failed to parse file"; file.close(); return 0; } file.close(); QDomElement docEle = document.documentElement(); QDomNodeList elements = docEle.elementsByTagName("LAMPS"); QDomElement light1 = document.createElement( "LIGHT1" ); QDomElement state = document.createElement("State"); QDomText nextNode = document.createTextNode("State"); state.appendChild(nextNode); light1.appendChild(state); docEle.appendChild( light1 ); QFile outFile( "test-result.xml" ); if( !outFile.open( QIODevice::WriteOnly | QIODevice::Text ) ) { qDebug( "Failed to open file for writing." ); return 0; } QTextStream stream( &outFile ); stream << document.toString(); outFile.close(); return 0; }来存储来自XML的内容。您可以创建新的子，标记，属性。

function range(start,end,step){
    let countx = [];
    if(typeof step==='undefined'){
        step=1;
        for(let start=1;start<=end;start+=step){
            countx.push(start);
        }
    }
    else {
        for(let i=start;i>=end;i+=step)
          countx.push(i);
        }
    return countx;
}

function sum(arrayx){
    let total=0;
    for(let i=0;i<=arrayx.length-1;i++){
          total+= (+arrayx[i]);
    }
    return total;
}
console.log(sum(range(1,10)));

修改XML文件QXMLStreamReader / Writer

1 个答案: