插槽错误使用QNetworkAccessManager [英] slot error using QNetworkAccessManager

问题描述

我尝试实施基本的http连接 http://developer.nokia.com/community / wiki / Creating_an_HTTP_network_request_in_Qt 到Qt，但我很难实施插槽。我是一个Qt新手。

C：\Qt5\Tools\QtCreator\bin\miniHTTP\main.cpp：10：错误：请求'mTest'中的成员'Test'，它是非类型'coreEng（）'
mTest.Test（）;

// main。 cpp

  #include< QCoreApplication> 
 #include< coreeng.h> 
 
 
 int main（int argc，char * argv []）
 {
 QCoreApplication a（argc，argv）; 
 
 coreEng mTest; 
 mTest.Test（） 
 return a.exec（）; 
} 
  

// coreeng.h

  #ifndef COREENG_H 
 #define COREENG_H 
 #include< QDebug> 
 #include< QObject> 
 #include< QNetworkAccessManager> 
 
 class coreEng：public QObject 
 {
 Q_OBJECT 
 public：
 explicit coreEng（QObject * parent = 0）; 
 void Test（）; 
私有插槽：
 
公共插槽：
 void connect（）; 
 void url（）; 
 void finishedSlot（）; 
 
 
 private：
 QNetworkAccessManager * nam; 
 
}; 
 
 #endif // COREENG_H 
  

// coreeng.cpp

  #includecoreeng.h
 #include< QNetworkAccessManager> 
 #include< QUrl> 
 #include< QNetworkRequest> 
 #include< QNetworkReply> 
 #include< QImageReader> 
 
 coreEng :: coreEng（QNetworkReply * parent）：
 QObject（parent）
 
 {
} 
 
 void coreEng ：：测试（）; 
 
 void coreEng :: connect（）{
 QObject :: connect（nam，SIGNAL（finished（QNetworkReply *）），
 this，SLOT（finishedSlot（QNetworkReply *）） ）; 
} 
 
 void coreEng :: url（）{
 QUrl url（http://www.forum.nokia.wiki）; 
 QNetworkReply * reply = nam-> get（QNetworkRequest（url））; 
} 
 
 
 void coreEng :: finishedSlot（QNetworkReply * reply）{
 
 QVariant statusCodeV = reply-> attribute（QNetworkRequest :: HttpStatusCodeAttribute） ; 
 
 QVariant redirectionTargetUrl = reply-> attribute（QNetworkRequest :: RedirectionTargetAttribute）; 
 
 if（reply-> error（）== QNetworkReply :: NoError）
 {
 
 QImageReader imageReader（reply）; 
 QImage pic = imageReader.read（）; 
 
 QByteArray bytes = reply-> readAll（）; // bytes 
 QString string（bytes）; // string 
} 
 
 else 
 {
 
} 
 
 delete reply; 
 
} 
  

解决方案

是你遇到最烦躁的解析： http://en.wikipedia.org/wiki/Most_vexing_parse

最讨厌的解析（C ++）

更改

  coreEng mTest 
  

到

  coreEng mTest;第二个问题是你的构造函数在coreeng.cpp中有错误的签名
 
 

更改：

  coreEng :: coreEng（QNetworkReply *）：
 QObject ）
  

到

 code> coreEng :: coreEng（QObject * parent）：
 QObject（parent）
  

I am trying to implement a basic http connection http://developer.nokia.com/community/wiki/Creating_an_HTTP_network_request_in_Qt into Qt but I have difficultly implementing the slot. I am a Qt novice.

C:\Qt5\Tools\QtCreator\bin\miniHTTP\main.cpp:10: error: request for member 'Test' in 'mTest', which is of non-class type 'coreEng()' mTest.Test();

//main.cpp

#include <QCoreApplication>
#include <coreeng.h>


int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    coreEng mTest;
    mTest.Test();
    return a.exec();
}

//coreeng.h

#ifndef COREENG_H
#define COREENG_H
#include <QDebug>
#include <QObject>
#include <QNetworkAccessManager>

class coreEng : public QObject
{
    Q_OBJECT
public:
    explicit coreEng(QObject *parent = 0);
    void Test();
private slots:

public slots:
    void connect();
    void url();
    void finishedSlot();


private:
    QNetworkAccessManager* nam;

};

#endif // COREENG_H

//coreeng.cpp

#include "coreeng.h"
#include <QNetworkAccessManager>
#include <QUrl>
#include <QNetworkRequest>
#include <QNetworkReply>
#include <QImageReader>

coreEng::coreEng(QNetworkReply* parent) :
    QObject(parent)

{
}

void coreEng::Test();

void coreEng::connect(){
    QObject::connect(nam, SIGNAL(finished(QNetworkReply*)),
    this, SLOT(finishedSlot(QNetworkReply*)));
}

void coreEng::url(){
    QUrl url("http://www.forum.nokia.wiki");
    QNetworkReply* reply = nam->get(QNetworkRequest(url));
}


void coreEng::finishedSlot(QNetworkReply* reply){

    QVariant statusCodeV = reply->attribute(QNetworkRequest::HttpStatusCodeAttribute);

    QVariant redirectionTargetUrl = reply->attribute(QNetworkRequest::RedirectionTargetAttribute);

    if (reply->error() == QNetworkReply::NoError)
    {

        QImageReader imageReader(reply);
        QImage pic = imageReader.read();

        QByteArray bytes = reply->readAll();  // bytes
        QString string(bytes); // string
    }

    else
    {

    }

    delete reply;

}

解决方案

One problem is you are running into the most vexing parse: http://en.wikipedia.org/wiki/Most_vexing_parse

Most vexing parse(C++)

Change

coreEng mTest();

to

coreEng mTest;

A second problem is your constructor in coreeng.cpp has the wrong signature

Change:

coreEng::coreEng(QNetworkReply*) :
    QObject(parent)

to

   coreEng::coreEng(QObject* parent) :
        QObject(parent)

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