如何在Qt中从网站获取文本（QNetworkAccessManager无法正常工作）？

Question

我正在尝试使用QNetworkAccessManager类从网站上获取文字，但它不起作用。 When the replyFinished slot above is called, the parameter it takes is the QNetworkReply object containing the downloaded data as well as meta-data (headers, etc.)。当调用插槽时，我将获取的文本附加到QString并将其打印出来，但它会打印一个空字符串。这是我的代码：

//.pro file
TEMPLATE = app
QT += qml quick
QT += network
CONFIG += c++11


//xmlparser.h
#ifndef XMLPARSER_H
#define XMLPARSER_H

#include <QObject>
#include <QNetworkAccessManager>

class XMLParser : public QNetworkAccessManager
{
    Q_OBJECT
public:
    ~XMLParser()=default;
    static XMLParser &Instance();
    Q_INVOKABLE void readXML();

signals:
    finished(QNetworkReply* reply);

public slots:
    void replyFinished(QNetworkReply* reply);

private:
    XMLParser()=default;
    XMLParser(XMLParser const&)=delete;
    void operator = (XMLParser const&)=delete;

    QByteArray m_text;
};

#endif // XMLPARSER_H


//xmlparser.cpp
#include <QUrl>
#include <QDebug>
#include <QNetworkAccessManager>
#include <QNetworkRequest>
#include <QNetworkReply>
#include <QEventLoop>
#include "xmlparser.h"

XMLParser &XMLParser::Instance()
{
    static XMLParser instance;
    return instance;
}
void XMLParser::readXML()
{
    QNetworkAccessManager *manager = new QNetworkAccessManager(this);
    connect(manager, SIGNAL(finished(QNetworkReply*)),
            this, SLOT(replyFinished(QNetworkReply*)));
    manager->get(QNetworkRequest(QUrl("http://qt-project.org")));
}
void XMLParser::replyFinished(QNetworkReply *reply)
{
    QString text;
    text.append(reply->readAll());
    qDebug () << "Text: " << text; //Prints out emtpy string?
}