Qt C++LNK2019:使用QNetworkAccessManager未解析的外部符号

我正在尝试使用此处提供的文档运行一段简单的代码https://doc.qt.io/qt-5/qnetworkaccessmanager.html.我在Windows 10上使用Qt Creator和MSVC2017 64位工具包。我对C++和类的知识是非常基础的。

代码给出了链接器错误，我不知道为什么。我试过再次进行清洁和重建，但没有成功。如有任何帮助，我们将不胜感激。谢谢

我用mainwindow.h 在Qt Creator中创建了一个新项目

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <QtNetwork/QNetworkAccessManager>
#include <QtNetwork/QNetworkReply>
QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
MainWindow(QWidget *parent = nullptr);    
~MainWindow();
void replyFinished(QNetworkReply *reply);
private:
Ui::MainWindow *ui;    
};
#endif // MAINWINDOW_H

然后在mainwindow.cpp中添加这些行并进行编译。

MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent)
, ui(new Ui::MainWindow)
{
ui->setupUi(this);
QNetworkAccessManager *manager = new QNetworkAccessManager(this);
connect(manager, &QNetworkAccessManager::finished,
this, &MainWindow::replyFinished);
manager->get(QNetworkRequest(QUrl("http://qt-project.org")));
}
void MainWindow::replyFinished(QNetworkReply *reply)
{
//
}

当我使用MSVC2017 64位工具包进行编译时，我在输出处收到链接器错误。如果我使用不同的套件(MinGW(，问题也是一样的。

这是我的.pro文件：

QT       += core gui
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
CONFIG += c++11
# The following define makes your compiler emit warnings if you use
# any Qt feature that has been marked deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS
# You can also make your code fail to compile if it uses deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0
SOURCES += 
main.cpp 
mainwindow.cpp
HEADERS += 
mainwindow.h
FORMS += 
mainwindow.ui
# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

以下是编译器输出：

12:52:23: Running steps for project Proj2...
12:52:23: Configuration unchanged, skipping qmake step.
12:52:23: Starting: "C:QtToolsQtCreatorbinjom.exe" 
C:QtToolsQtCreatorbinjom.exe -f Makefile.Debug
link /NOLOGO /DYNAMICBASE /NXCOMPAT /DEBUG /SUBSYSTEM:WINDOWS "/MANIFESTDEPENDENCY:type='win32' name='Microsoft.Windows.Common-Controls' version='6.0.0.0' publicKeyToken='6595b64144ccf1df' language='*' processorArchitecture='*'" /MANIFEST:embed /OUT:debugProj2.exe @C:UsersHPAppDataLocalTempProj2.exe.7376.15.jom
mainwindow.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __cdecl QNetworkRequest::QNetworkRequest(class QUrl const &)" (__imp_??0QNetworkRequest@@QEAA@AEBVQUrl@@@Z) referenced in function "public: __cdecl MainWindow::MainWindow(class QWidget *)" (??0MainWindow@@QEAA@PEAVQWidget@@@Z)
mainwindow.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __cdecl QNetworkRequest::~QNetworkRequest(void)" (__imp_??1QNetworkRequest@@QEAA@XZ) referenced in function "public: __cdecl MainWindow::MainWindow(class QWidget *)" (??0MainWindow@@QEAA@PEAVQWidget@@@Z)
mainwindow.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __cdecl QNetworkAccessManager::QNetworkAccessManager(class QObject *)" (__imp_??0QNetworkAccessManager@@QEAA@PEAVQObject@@@Z) referenced in function "public: __cdecl MainWindow::MainWindow(class QWidget *)" (??0MainWindow@@QEAA@PEAVQWidget@@@Z)
mainwindow.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: virtual __cdecl QNetworkAccessManager::~QNetworkAccessManager(void)" (__imp_??1QNetworkAccessManager@@UEAA@XZ) referenced in function "public: virtual void * __cdecl QNetworkAccessManager::`scalar deleting destructor'(unsigned int)" (??_GQNetworkAccessManager@@UEAAPEAXI@Z)
mainwindow.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: class QNetworkReply * __cdecl QNetworkAccessManager::get(class QNetworkRequest const &)" (__imp_?get@QNetworkAccessManager@@QEAAPEAVQNetworkReply@@AEBVQNetworkRequest@@@Z) referenced in function "public: __cdecl MainWindow::MainWindow(class QWidget *)" (??0MainWindow@@QEAA@PEAVQWidget@@@Z)
mainwindow.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: void __cdecl QNetworkAccessManager::finished(class QNetworkReply *)" (__imp_?finished@QNetworkAccessManager@@QEAAXPEAVQNetworkReply@@@Z) referenced in function "public: __cdecl MainWindow::MainWindow(class QWidget *)" (??0MainWindow@@QEAA@PEAVQWidget@@@Z)
mainwindow.obj : error LNK2001: unresolved external symbol "protected: virtual class QNetworkReply * __cdecl QNetworkAccessManager::createRequest(enum QNetworkAccessManager::Operation,class QNetworkRequest const &,class QIODevice *)" (?createRequest@QNetworkAccessManager@@MEAAPEAVQNetworkReply@@W4Operation@1@AEBVQNetworkRequest@@PEAVQIODevice@@@Z)
mainwindow.obj : error LNK2001: unresolved external symbol "public: virtual struct QMetaObject const * __cdecl QNetworkAccessManager::metaObject(void)const " (?metaObject@QNetworkAccessManager@@UEBAPEBUQMetaObject@@XZ)
mainwindow.obj : error LNK2001: unresolved external symbol "public: virtual int __cdecl QNetworkAccessManager::qt_metacall(enum QMetaObject::Call,int,void * *)" (?qt_metacall@QNetworkAccessManager@@UEAAHW4Call@QMetaObject@@HPEAPEAX@Z)
mainwindow.obj : error LNK2001: unresolved external symbol "public: virtual void * __cdecl QNetworkAccessManager::qt_metacast(char const *)" (?qt_metacast@QNetworkAccessManager@@UEAAPEAXPEBD@Z)
mainwindow.obj : error LNK2001: unresolved external symbol "__declspec(dllimport) public: static struct QMetaObject const QNetworkAccessManager::staticMetaObject" (__imp_?staticMetaObject@QNetworkAccessManager@@2UQMetaObject@@B)
Hint on symbols that are defined and could potentially match:
"__declspec(dllimport) public: static struct QMetaObject const QMainWindow::staticMetaObject" (__imp_?staticMetaObject@QMainWindow@@2UQMetaObject@@B)
mainwindow.obj : error LNK2001: unresolved external symbol "__declspec(dllimport) public: static struct QMetaObject const QNetworkReply::staticMetaObject" (__imp_?staticMetaObject@QNetworkReply@@2UQMetaObject@@B)
Hint on symbols that are defined and could potentially match:
"__declspec(dllimport) public: static struct QMetaObject const QMainWindow::staticMetaObject" (__imp_?staticMetaObject@QMainWindow@@2UQMetaObject@@B)
debugProj2.exe : fatal error LNK1120: 12 unresolved externals