QString fileName = QFileDialog::getOpenFileName(this);

#include "dialog.h"
#include "ui_dialog.h"
#include <QtWidgets>

Dialog::Dialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Dialog)
{
    ui->setupUi(this);
}

Dialog::~Dialog()
{
    delete ui;
}

void Dialog::on_pushButton_clicked()
{
    QString fileName = QFileDialog::getOpenFileName(this);
    if (!fileName.isEmpty())
    {
        //loadFile(fileName);
        ui->lineEdit->setText(fileName);
    }

}

void Dialog::on_pushButton_2_clicked()
{
    //定义文件对话框类
    QFileDialog *fileDialog = new QFileDialog(this);
    //定义文件对话框标题
    fileDialog->setWindowTitle(tr("打开图片"));
    //设置默认文件路径
    //fileDialog->setDirectory(".");
    //
    //设置文件过滤器
    fileDialog->setNameFilter(tr("Images(*.png *.jpg *.jpeg *.bmp)"));
    //设置可以选择多个文件,默认为只能选择一个文件QFileDialog::ExistingFiles
    fileDialog->setFileMode(QFileDialog::ExistingFiles);
    //设置视图模式
    fileDialog->setViewMode(QFileDialog::Detail);
    //打印所有选择的文件的路径
    QStringList fileNames;
    if(fileDialog->exec())
    {
        fileNames = fileDialog->selectedFiles();
    }
    for(auto tmp:fileNames)
    {
        qDebug()<<tmp<<endl;
    }
}