问题描述
我想要在我的Qt程序中的以下链接上显示的字符串如何获得它?
我已编码以下文件,以获取字符串出现在m_DownloadedData上面的页面,但它在程序结束时存储空字符串,有人可以帮助我获取数据从上面的链接?
.h文件:
#ifndef SKYOBJDESCRIPTION_H
#define SKYOBJDESCRIPTION_H
#include< QObject>
#include< QByteArray>
#include< QString>
#include< QNetworkAccessManager>
#include< QNetworkRequest>
#include< QNetworkReply>
class SkyObjDescription:public QObject
{
Q_OBJECT
public:
explicit SkyObjDescription(const QString soName,const QString soType,QObject * parent = 0) ;
virtual〜SkyObjDescription();
QByteArray downloadedData()const;
信号:
void downloaded();
私有插槽:
void fileDownloaded(QNetworkReply * reply);
private:
QString soName,soType;
QByteArray m_DownloadedData;
};
#endif // SKYOBJDESCRIPTION_H
和
.cpp档案
#include< QString>
#include< QUrl>
#include< QDebug>
#includeskyobjdescription.h
SkyObjDescription :: SkyObjDescription(const QString so_Name,const QString so_Type,QObject * parent):soName(so_Name) soType(so_Type),QObject(parent)
{
QString wikiLink =http://en.wikipedia.org/w/api.php?action=opensearch&search=\"+ soName.replace ,_)。toLower()+_+ soType.toLower()+& format = xml& limit = 1.xml;
// QUrl wikiUrl(http://en.wikipedia.org/w/api.php?action=opensearch&search=hello_world&format=xml&limit=1.xml);
m_DownloadedData = wikiUrl.toEncoded();
qDebug()<< wikiUrl.toEncoded():< m_DownloadedData;
QNetworkRequest req(wikiUrl);
QNetworkAccessManager * manager = new QNetworkAccessManager(this);
connect(manager,SIGNAL(finished(QNetworkReply *)),SLOT(fileDownloaded(QNetworkReply *)));
manager-> get(req);
}
SkyObjDescription ::〜SkyObjDescription()
{
}
void SkyObjDescription fileDownloaded(QNetworkReply * reply)
{
m_DownloadedData = reply-> readAll();
qDebug()<< received reply;
qDebug()<< m_DownloadedData;
reply-> deleteLater();
emit downloaded();
}
QByteArray SkyObjDescription :: downloadedData()const
{
qDebug()< m_DownloadedData;
return m_DownloadedData;
}
部分main.cpp
SkyObjDescription * skd = new SkyObjDescription(m_Name,Constellation);
QString data(skd-> downloadedData());
qDebug()<<数据;
delete skd;
如果有其他方式从链接获取数据,请解释。
非常感谢:)
你可能试验的是你的双重呼叫 QNetworkReply :: readAll
。
记住它是一个IO操作,并且没有办法多次读取netwrk回复。
只需注释您的调试行:
void SkyObjDescription :: fileDownloaded(QNetworkReply * pReply)
{
// qDebug()<< pReply-> readAll();
m_DownloadedData = pReply-> readAll();
//发出一个信号
pReply-> deleteLater();
emit downloaded();
}
编辑(完整性)
我使用的测试代码:
#ifndef TMP_H
#define TMP_H
#include< QObject>
class QNetworkReply;
class Tmp:public QObject
{
Q_OBJECT
public:
explicit Tmp(QObject * parent = 0);
信号:
公共位置:
void displayResult(QNetworkReply * reply);
};
#endif // TMP_H
//tmp.cpp
#includetmp.h
#include< QNetworkAccessManager>
#include< QNetworkReply>
#include< QNetworkRequest>
#include< QDebug>
Tmp :: Tmp(QObject * parent):
QObject(parent)
{
QUrl url(http://en.wikipedia.org/wiki / Centaurus_constellation);
QNetworkRequest req(url);
QNetworkAccessManager * manager = new QNetworkAccessManager(this);
connect(manager,SIGNAL(finished(QNetworkReply *)),SLOT(displayResult(QNetworkReply *)));
manager-> get(req);
}
void Tmp :: displayResult(QNetworkReply * reply){
QByteArray buffer = reply-> readAll();
qDebug()<< received reply;
qDebug()<<缓冲;
reply-> deleteLater();
}
I want to get string that appears on following link in my Qt program how can I get it ?
http://en.wikipedia.org/w/api.php?action=opensearch&search=centaurus_constellation
I have coded following files to get string appearing on above page in m_DownloadedData, but it is storing empty string at the end of the program , can someone please help me get data from above link ?
.h file:
#ifndef SKYOBJDESCRIPTION_H
#define SKYOBJDESCRIPTION_H
#include <QObject>
#include <QByteArray>
#include <QString>
#include <QNetworkAccessManager>
#include <QNetworkRequest>
#include <QNetworkReply>
class SkyObjDescription : public QObject
{
Q_OBJECT
public:
explicit SkyObjDescription(const QString soName, const QString soType, QObject* parent = 0);
virtual ~SkyObjDescription();
QByteArray downloadedData() const;
signals:
void downloaded();
private slots:
void fileDownloaded(QNetworkReply* reply);
private:
QString soName,soType;
QByteArray m_DownloadedData;
};
#endif // SKYOBJDESCRIPTION_H
and.cpp file
#include <QString>
#include <QUrl>
#include <QDebug>
#include "skyobjdescription.h"
SkyObjDescription::SkyObjDescription(const QString so_Name, const QString so_Type, QObject* parent): soName(so_Name), soType(so_Type), QObject(parent)
{
QString wikiLink = "http://en.wikipedia.org/w/api.php?action=opensearch&search="+ soName.replace(" ", "_").toLower() + "_" + soType.toLower() + "&format=xml&limit=1.xml";
// QUrl wikiUrl("http://en.wikipedia.org/w/api.php?action=opensearch&search=hello_world&format=xml&limit=1.xml");
m_DownloadedData = wikiUrl.toEncoded();
qDebug() << "wikiUrl.toEncoded(): " << m_DownloadedData;
QNetworkRequest req(wikiUrl);
QNetworkAccessManager* manager = new QNetworkAccessManager(this);
connect(manager, SIGNAL(finished(QNetworkReply*)), SLOT(fileDownloaded(QNetworkReply*)));
manager->get(req);
}
SkyObjDescription::~SkyObjDescription()
{
}
void SkyObjDescription::fileDownloaded(QNetworkReply* reply)
{
m_DownloadedData = reply->readAll();
qDebug() << "received reply";
qDebug() << m_DownloadedData;
reply->deleteLater();
emit downloaded();
}
QByteArray SkyObjDescription::downloadedData() const
{
qDebug() << m_DownloadedData;
return m_DownloadedData;
}
part of main.cpp
SkyObjDescription * skd = new SkyObjDescription(m_Name, "Constellation");
QString data(skd->downloadedData());
qDebug() << data;
delete skd;
If there is other way to get data from link please explain it.Thank you very much :)
What you probably experiment is caused by your double call on QNetworkReply::readAll
.
Remembers it is a IO operation, and there is no way to read multiple times the information contain by the netwrk reply.
Just comment your debug line :
void SkyObjDescription::fileDownloaded(QNetworkReply* pReply)
{
//qDebug() << pReply->readAll();
m_DownloadedData = pReply->readAll();
//emit a signal
pReply->deleteLater();
emit downloaded();
}
edit (for completness)
The test code I use :
#ifndef TMP_H
#define TMP_H
#include <QObject>
class QNetworkReply;
class Tmp : public QObject
{
Q_OBJECT
public:
explicit Tmp(QObject *parent = 0);
signals:
public slots:
void displayResult(QNetworkReply* reply);
};
#endif // TMP_H
//tmp.cpp
#include "tmp.h"
#include <QNetworkAccessManager>
#include <QNetworkReply>
#include <QNetworkRequest>
#include <QDebug>
Tmp::Tmp(QObject *parent) :
QObject(parent)
{
QUrl url("http://en.wikipedia.org/wiki/Centaurus_constellation");
QNetworkRequest req(url);
QNetworkAccessManager* manager = new QNetworkAccessManager(this);
connect(manager, SIGNAL(finished(QNetworkReply*)), SLOT(displayResult(QNetworkReply*)));
manager->get(req);
}
void Tmp::displayResult(QNetworkReply *reply) {
QByteArray buffer = reply->readAll();
qDebug() << "received reply";
qDebug() << buffer;
reply->deleteLater();
}
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