QT文件操作(QT实操学习3)

1.项目架构

1.UI界面

1.新建文本文档

2.打开文件

3.另存为文件

2.mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H#include <QMainWindow>
#include <QFileDialog>
#include <QMessageBox>
#include <QDebug>
QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACEclass MainWindow : public QMainWindow
{Q_OBJECTpublic:MainWindow(QWidget *parent = nullptr);~MainWindow();private slots:void newActionSlot();void openActionSlot();void saveActionSlot();private:Ui::MainWindow *ui;
};
#endif // MAINWINDOW_H

3.main.cpp

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

3.mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"MainWindow::MainWindow(QWidget *parent): QMainWindow(parent), ui(new Ui::MainWindow)
{ui->setupUi(this);connect(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()
{ui->textEdit->clear();this->setWindowTitle("新建文本文档.txt");
}void MainWindow::openActionSlot()
{QString fileName = QFileDialog::getOpenFileName(this, "open",QCoreApplication::applicationFilePath(),"*.cpp");if (fileName.isEmpty()){QMessageBox::warning(this,"警告","请选择一个文件");}else{
//        qDebug()<<fileName;QFile file(fileName);//创建文件对象file.open(QIODevice::ReadOnly);QByteArray ba = file.readAll();ui->textEdit->setText(QString(ba));file.close();}}void MainWindow::saveActionSlot()
{QString fileName = QFileDialog::getSaveFileName(this,"save",QCoreApplication::applicationFilePath());if (fileName.isEmpty()){QMessageBox::warning(this,"警告","请选择一个文件");}else{QFile file(fileName);//创建文件对象file.open(QIODevice::WriteOnly);QByteArray ba;ba.append(ui->textEdit->toPlainText());file.write(ba);file.close();}
}

2. 程序讲解

1. 初始化界面

MainWindow::MainWindow(QWidget *parent): QMainWindow(parent), ui(new Ui::MainWindow)
{ui->setupUi(this);connect(ui->newAction, &QAction::triggered, this, &MainWindow::newActionSlot);connect(ui->openAction, &QAction::triggered, this, &MainWindow::openActionSlot);connect(ui->saveAction, &QAction::triggered, this, &MainWindow::saveActionSlot);
}

界面设置：构造函数中初始化UI组件。
信号槽连接：将菜单项的动作（新建、打开、保存）与对应的槽函数连接起来。

2. 新建文件

void MainWindow::newActionSlot()
{ui->textEdit->clear();this->setWindowTitle("新建文本文档.txt");
}

清空文本：调用textEdit->clear()清空文本编辑器的内容。
设置窗口标题：将窗口标题设置为“新建文本文档.txt”。

3. 打开文件

void MainWindow::openActionSlot()
{QString fileName = QFileDialog::getOpenFileName(this, "open",QCoreApplication::applicationFilePath(), "*.cpp");if (fileName.isEmpty()){QMessageBox::warning(this, "警告", "请选择一个文件");}else{QFile file(fileName);file.open(QIODevice::ReadOnly);QByteArray ba = file.readAll();ui->textEdit->setText(QString(ba));file.close();}
}

打开文件对话框：使用QFileDialog::getOpenFileName打开文件选择对话框。
检查文件名：如果用户没有选择文件，显示警告消息。
读取文件内容：打开文件，读取所有内容，并将其显示在文本编辑器中。

4. 保存文件

void MainWindow::saveActionSlot()
{QString fileName = QFileDialog::getSaveFileName(this, "save",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());file.write(ba);file.close();}
}