I have already #include <QtWebSockets/QWebSocket> and set the QT Project Setting and checked WebKit and Network Module。

and this is the full error message I have got :

1>mainwindow.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: virtual __thiscall QWebSocket::~QWebSocket(void)" (_imp??1QWebSocket@@UAE@XZ)，referenced in function "public: virtual __thiscall MWebSocket::~MWebSocket(void)" (??1MWebSocket@@UAE@XZ) 1>MWebSocket.obj : error LNK2001: unresolved external symbol "__declspec(dllimport) public: virtual __thiscall QWebSocket::~QWebSocket(void)" (_imp??1QWebSocket@@UAE@XZ) 1>MWebSocket.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __thiscall QWebSocket::QWebSocket(class QString const &,enum QWebSocketProtocol::Version,class QObject *)" (_imp??0QWebSocket@@QAE@ABVQString@@W4Version@QWebSocketProtocol@@PAVQObject@@@Z)，referenced in function "public: __thiscall MWebSocket::MWebSocket(class QUrl const &,class QObject *)" (??0MWebSocket@@QAE@ABVQUrl@@PAVQObject@@@Z) 1>MWebSocket.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __int64 __thiscall QWebSocket::sendTextMessage(class QString const &)" (_imp?sendTextMessage@QWebSocket@@QAE_JABVQString@@@Z)，referenced in function "private: void __thiscall MWebSocket::onConnected(void)" (?onConnected@MWebSocket@@AAEXXZ) 1>MWebSocket.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: void __thiscall QWebSocket::close(enum QWebSocketProtocol::CloseCode,class QString const &)" (_imp?close@QWebSocket@@QAEXW4CloseCode@QWebSocketProtocol@@ABVQString@@@Z)，referenced in function "private: void __thiscall MWebSocket::onTextMessageReceived(class QString)" (?onTextMessageReceived@MWebSocket@@AAEXVQString@@@Z) 1>MWebSocket.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: void __thiscall QWebSocket::open(class QUrl const &)" (_imp?open@QWebSocket@@QAEXABVQUrl@@@Z)，referenced in function "public: __thiscall MWebSocket::MWebSocket(class QUrl const &,class QObject *)" (??0MWebSocket@@QAE@ABVQUrl@@PAVQObject@@@Z) 1>MWebSocket.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: void __thiscall QWebSocket::connected(void)" (_imp?connected@QWebSocket@@QAEXXZ)，referenced in function "public: __thiscall MWebSocket::MWebSocket(class QUrl const &,class QObject *)" (??0MWebSocket@@QAE@ABVQUrl@@PAVQObject@@@Z) 1>MWebSocket.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: void __thiscall QWebSocket::disconnected(void)" (_imp?disconnected@QWebSocket@@QAEXXZ)，referenced in function "public: __thiscall MWebSocket::MWebSocket(class QUrl const &,class QObject *)" (??0MWebSocket@@QAE@ABVQUrl@@PAVQObject@@@Z) 1>MWebSocket.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: void __thiscall QWebSocket::textMessageReceived(class QString const &)" (_imp?textMessageReceived@QWebSocket@@QAEXABVQString@@@Z)，referenced in function "private: void __thiscall MWebSocket::onConnected(void)" (?onConnected@MWebSocket@@AAEXXZ) 1>MWebSocket.obj : error LNK2001: unresolved external symbol "__declspec(dllimport) public: static struct QMetaObject const QWebSocket::staticMetaObject" (_imp?staticMetaObject@QWebSocket@@2UQMetaObject@@B) 1>debug/\MapleUI.exe : fatal error LNK1120: 9 unresolved externals

this is the code for Websocket:

@
//HEADER
#pragma once
#include "global.h"

class MWebSocket : public QObject
{
Q_OBJECT
public:
explicit MWebSocket(const QUrl &url, QObject *parent = Q_NULLPTR);

Q_SIGNALS:
void closed();

private Q_SLOTS:
void onConnected();
void onTextMessageReceived(QString message);

private:
QWebSocket m_webSocket;
QUrl m_url;
};

//CPP

#include "global.h"
#include "MWebSocket.h"

QT_USE_NAMESPACE

//! [constructor]
MWebSocket::MWebSocket(const QUrl &url, QObject *parent) :
QObject(parent),
m_url(url)
{
connect(&m_webSocket, &QWebSocket::connected, this, &MWebSocket::onConnected);
connect(&m_webSocket, &QWebSocket::disconnected, this, &MWebSocket::closed);
m_webSocket.open(QUrl(url));
}
//! [constructor]

//! [onConnected]
void MWebSocket::onConnected()
{
qDebug() << "WebSocket connected";
connect(&m_webSocket, &QWebSocket::textMessageReceived,
this, &MWebSocket::onTextMessageReceived);
m_webSocket.sendTextMessage(QStringLiteral("H2ello, world!"));
}
//! [onConnected]

//! [onTextMessageReceived]
void MWebSocket::onTextMessageReceived(QString message)
{
qDebug() << "Message received:" << message;
m_webSocket.close();
}
//! [onTextMessageReceived]

@
anyone have idea about how to solve this problem? thanks