QT文件操作【记事本】

mainwindow.h

核心函数

• QFileDialog::getOpenFileName()
• QFileDialog::getSaveFileName()

#ifndef MAINWINDOW_H
#define MAINWINDOW_H#include <QMainWindow>
#include<QFileDialog>
#include<QMessageBox>
#include<QDebug>
#include<QFile>
#include<QKeyEvent>
#include<QMouseEvent>QT_BEGIN_NAMESPACE
namespace Ui {
class MainWindow;
}
QT_END_NAMESPACEclass MainWindow : public QMainWindow
{Q_OBJECTpublic:MainWindow(QWidget *parent = nullptr);void keyPressEvent(QKeyEvent *k);//父类虚函数，键盘按下事件void mousePressEvent(QMouseEvent *m);//鼠标按下事件~MainWindow();private:Ui::MainWindow *ui;
private slots:void newActionSlot();void openActionSlot();void saveActionSlot();
};
#endif // MAINWINDOW_H

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"MainWindow::MainWindow(QWidget *parent): QMainWindow(parent), ui(new Ui::MainWindow)
{ui->setupUi(this);this->setWindowTitle("记事本");//连接函数，谁发出信息，发出什么信号，谁接收信号，执行什么操作//自定义三个槽函数，newActionSlot,openActionSlot,saveActionSlotconnect(ui->newAction,&QAction::triggered,this,&MainWindow::newActionSlot);connect(ui->openAction,&QAction::triggered,this,&MainWindow::openActionSlot);connect(ui->saveAction,&QAction::triggered,this,&MainWindow::saveActionSlot);
}MainWindow::~MainWindow()
{delete ui;
}
void MainWindow::newActionSlot()
{
//清空内容ui->textEdit->clear();this->setWindowTitle("新建文本文档.txt");
}
void MainWindow::openActionSlot()
{
//打开文件资源管理窗口，获取选定的文件的路径QString filename= QFileDialog::getOpenFileName(this, "打开文件",QCoreApplication::applicationFilePath(), "*.cpp");if(filename.isEmpty()){QMessageBox::warning(this,"警告","请打开一个文件！");}else{//qDebug() << filename;//通过文件路径，构建文件对象QFile file(filename);//只读方式打开file.open(QIODevice::ReadOnly);//读取文件中的所有内容到字节数组中QByteArray ba = file.readAll();//关闭文件对象file.close();//将读取的数据存储到textEdit中ui->textEdit->setText(QString(ba));}
}
void MainWindow::saveActionSlot()
{
//弹出文件资源管理器窗口，选择文件夹。
//QCoreApplication::applicationFilePath()表示当前根目录QString filename=QFileDialog::getSaveFileName(this,"保存文件",QCoreApplication::applicationFilePath());if(filename.isEmpty())QMessageBox::warning(this,"警告","请选择一个文件！");else{QFile file(filename);file.open(QIODevice::WriteOnly);QByteArray ba;ba.append(ui->textEdit->toPlainText().toUtf8());file.write(ba);file.close();QMessageBox::about(this,"提示","保存成功");}
}void MainWindow::keyPressEvent(QKeyEvent *k)
{
//键盘按下事件，一个父类的虚函数，能够检测键盘事件。Ctrl+S调用保存函数if(k->modifiers()==Qt::ControlModifier&&k->key()==Qt::Key_S)saveActionSlot();
}void MainWindow::mousePressEvent(QMouseEvent *m)
{QPoint pt = m->pos();qDebug()<<pt;if(m->button()==Qt::LeftButton)qDebug()<<"左键被按下";else if(m->button()==Qt::RightButton)qDebug()<<"右键被按下";
}