QGIS二次开发新建工程并显示一个图层

#pragma once
#include
#include "ui_qtwidgetsapplication.h"
#include
#include
#include
class QtWidgetsApplication : public QMainWindow
{
Q_OBJECT
public:
QtWidgetsApplication(QWidget *parent = Q_NULLPTR);
private:
Ui::QtWidgetsApplicationClass ui;

QMenu* fileMenu;
QAction* openFileAction;
QgsMapCanvas* mapCanvas;
QList layers;
public slots:
void on_openFileAction_triggered();
//

public:
void addVectorLayer();
};

#include "qtwidgetsapplication.h"
#include
#include
#include
#include
QtWidgetsApplication::QtWidgetsApplication(QWidget *parent)
: QMainWindow(parent)
{
ui.setupUi(this);
this->resize(600, 400);
// create the menus and then add the actions to them.
fileMenu = this->menuBar()->addMenu("File");
openFileAction = new QAction("Open", this);
this->connect(openFileAction, SIGNAL(triggered(bool)), this, SLOT(on_openFileAction_triggered()));
fileMenu->addAction(openFileAction);
// initialize the map canvas
mapCanvas = new QgsMapCanvas();
this->setCentralWidget(mapCanvas);
mapCanvas->setCanvasColor(QColor(255, 255, 255));
mapCanvas->setVisible(true);
mapCanvas->enableAntiAliasing(true);

}
void QtWidgetsApplication::on_openFileAction_triggered()
{
addVectorLayer();
}
void QtWidgetsApplication::addVectorLayer()
{
QString fileName = QFileDialog::getOpenFileName(this, tr("Open shape file"), "", "*.shp");
//QString fileName = QFileDialog::getOpenFileName(this, tr("Open shape file"), "", "*");
QStringList temp = fileName.split(‘/‘);
QString basename = temp.at(temp.size() - 1);
QgsVectorLayer* vecLayer = new QgsVectorLayer(fileName, basename, "ogr");
if (!vecLayer->isValid())
{
QMessageBox::critical(this, "error", QString("layer is invalid: \n") + fileName);
return;
}
mapCanvas->setExtent(vecLayer->extent());
layers.append(vecLayer);
mapCanvas->setLayers(layers);
mapCanvas->refresh();
}

#include "qtwidgetsapplication.h"
#include
#include
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QtWidgetsApplication w;
w.show();
return a.exec();
}