一、实现简易文本编辑器

主要用到带菜单栏的窗口，而非单一窗口。QT已经写好相关操作，就不在重新造轮子了
功能设计：新建文本文档，打开文件，保存文件，另存为

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这次不同于之前直接可以在控件上面右击槽了；而是需要自己手动去进行连接信号与槽

private slots:void newTextAction();               //新建文档void openTextAction();              //打开文档void saveTextAction();              //保存文档void saveAnotherAction();           //文档另存为//构造函数中，连接信号与槽
connect(ui->new_file_Action, &QAction::triggered, this, &MainWindow::newTextAction);
connect(ui->open_file_Action, &QAction::triggered, this, &MainWindow::openTextAction);
connect(ui->save_file_Action, &QAction::triggered, this, &MainWindow::saveTextAction);
connect(ui->save_another_file_Action, &QAction::triggered, this, &MainWindow::saveAnotherAction);

新建文本文档：将之前的内容清空

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

打开文档，读取里面内容

void MainWindow::openTextAction()
{QString current_path = QCoreApplication::applicationFilePath();             //获取当前文件路径QString file_Name = QFileDialog::getOpenFileName(this, tr("打开文件"),current_path,tr("Text files (*.txt *.c *.cpp)"));if(file_Name.isNull()){QMessageBox::warning(this, "警告","请选择一个文件");}else{QFile file(file_Name);if (!file.open(QIODevice::ReadOnly | QIODevice::Text))return;QTextStream in(&file);QString content = in.readAll();ui->textEdit->setText(content);file.close();//记录当前路径m_current_file_path = file_Name;}
}

保存文档,将编辑框里面的内容写入文档中<=============>将内存中的数据持久化到磁盘上

void MainWindow::saveTextAction()
{//如果当前没有打开文件，那么就另存为if(m_current_file_path.isEmpty()){this->saveAnotherAction();return;}QFile file(m_current_file_path);if(!file.open(QIODevice::WriteOnly | QIODevice::Text)){QMessageBox::warning(this, "错误","无法保存文件");return;}QTextStream out(&file);out<<ui->textEdit->toPlainText();file.close();QMessageBox::information(this, "成功","保存文件");
}

和保存功能一样，不过需要新添选择新路径这一项

void MainWindow::saveAnotherAction()
{QString current_path = QCoreApplication::applicationFilePath();             //获取当前文件路径QString save_path = QFileDialog::getSaveFileName(this, tr("保存文件"),current_path,tr("Text files (*.txt *.c *.cpp)"));if(save_path.isNull()){QMessageBox::warning(this, "警告","请选择保存位置");}else{QFile file(save_path);if (!file.open(QIODevice::WriteOnly | QIODevice::Text)){QMessageBox::warning(this, "错误", "无法保存文件");return;}QTextStream out(&file);out<<ui->textEdit->toPlainText();file.close();//更新当前路径m_current_file_path = save_path;//设置标题this->setWindowTitle(QFileInfo(save_path).fileName());QMessageBox::information(this, "成功","保存文件");}
}

实现下快捷键操作,需要添加处理按键的响应函数

void MainWindow::keyPressEvent(QKeyEvent *event)
{if (event->modifiers() & Qt::ControlModifier){switch(event->key()){case Qt::Key_N: this->newTextAction();  break;case Qt::Key_O: this->openTextAction(); break;case Qt::Key_S:{if(event->modifiers() & Qt::ShiftModifier){this->saveAnotherAction();}else{this->saveTextAction();}break;}default:QMainWindow::keyPressEvent(event);  // 调用基类处理}}else{QMainWindow::keyPressEvent(event);  // 调用基类处理}
}

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