QFileDialog，也就是文件对话框。在本节中，我们将尝试编写一个简单的文本文件编辑器，我们将使用QFileDialog来打开一个文本文件，并将修改过的文件保存到硬盘。这或许是我们在本系列中所提供的第一个带有实际功能的实例。
首先，我们需要创建一个带有文本编辑功能的窗口
openAction = new QAction(QIcon(":/images/file-open"), tr("&Open..."), this);
openAction->setShortcuts(QKeySequence::Open);
openAction->setStatusTip(tr("Open an existing file"));
saveAction = new QAction(QIcon(":/images/file-save"), tr("&Save..."), this);
saveAction->setShortcuts(QKeySequence::Save);
saveAction->setStatusTip(tr("Save a new file"));
QMenu *file = menuBar()->addMenu(tr("&File"));
file->addAction(openAction);
file->addAction(saveAction);
QToolBar *toolBar = addToolBar(tr("&File"));
toolBar->addAction(openAction);
toolBar->addAction(saveAction);
textEdit = new QTextEdit(this);
setCentralWidget(textEdit);
QTextEdit类，这个类用于显示富文本文件。也就是说，它不仅仅用于显示文本，还可以显示图片、表格等等。
我们使用connect()函数，为这两个QAction对象添加响应的动作：
/// !!!Qt5
connect(openAction, &QAction::triggered, this, &MainWindow::openFile);
connect(saveAction, &QAction::triggered, this, &MainWindow::saveFile);
下面是最主要的openFile()和saveFile()这两个函数的代码：
void MainWindow::openFile()
{
QString path = QFileDialog::getOpenFileName(this,
tr("Open File"),
".",
tr("Text Files(*.txt)"));
if(!path.isEmpty()) {
QFile file(path);
if (!file.open(QIODevice::ReadOnly | QIODevice::Text)) {
QMessageBox::warning(this, tr("Read File"),
tr("Cannot open file:\n%1").arg(path));
return;
}
QTextStream in(&file);
textEdit->setText(in.readAll());
file.close();
} else {
QMessageBox::warning(this, tr("Path"),
tr("You did not select any file."));
}
}
void MainWindow::saveFile()
{
QString path = QFileDialog::getSaveFileName(this,
tr("Open File"),
".",
tr("Text Files(*.txt)"));
if(!path.isEmpty()) {
QFile file(path);
if (!file.open(QIODevice::WriteOnly | QIODevice::Text)) {
QMessageBox::warning(this, tr("Write File"),
tr("Cannot open file:\n%1").arg(path));
return;
}
QTextStream out(&file);
out << textEdit->toPlainText();
file.close();
} else {
QMessageBox::warning(this, tr("Path"),
tr("You did not select any file."));
}
}
完整代码：
mianwindow,h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
class QTextEdit;
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
private slots:
void openFile();
void saveFile();
private:
QAction *openAction;
QAction *saveAction;
QTextEdit *textEdit;
};
#endif // MAINWINDOW_H
mainwindow.cpp
#include <QtGui>
#include <QtWidgets>
#include "mainwindow.h"
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent)
{
openAction = new QAction(QIcon(":/images/file-open"), tr("&Open..."), this);
openAction->setShortcuts(QKeySequence::Open);
openAction->setStatusTip(tr("Open an existing file"));
connect(openAction, &QAction::triggered, this, &MainWindow::openFile);
saveAction = new QAction(QIcon(":/images/file-save"), tr("&Save..."), this);
saveAction->setShortcuts(QKeySequence::Save);
saveAction->setStatusTip(tr("Save a new file"));
connect(saveAction, &QAction::triggered, this, &MainWindow::saveFile);
QMenu *file = menuBar()->addMenu(tr("&File"));
file->addAction(openAction);
file->addAction(saveAction);
QToolBar *toolBar = addToolBar(tr("&File"));
toolBar->addAction(openAction);
toolBar->addAction(saveAction);
textEdit = new QTextEdit(this);
setCentralWidget(textEdit);
}
MainWindow::~MainWindow()
{
}
void MainWindow::openFile()
{
QString path = QFileDialog::getOpenFileName(this, tr("Open File"), ".", tr("Text Files(*.txt)"));
if(!path.isEmpty()) {
QFile file(path);
if (!file.open(QIODevice::ReadOnly | QIODevice::Text)) {
QMessageBox::warning(this, tr("Read File"), tr("Cannot open file:\n%1").arg(path));
return;
}
QTextStream in(&file);
textEdit->setText(in.readAll());
file.close();
} else {
QMessageBox::warning(this, tr("Path"), tr("You did not select any file."));
}
}
void MainWindow::saveFile()
{
QString path = QFileDialog::getSaveFileName(this, tr("Save File"), ".", tr("Text Files(*.txt)"));
if(!path.isEmpty()) {
QFile file(path);
if (!file.open(QIODevice::WriteOnly | QIODevice::Text)) {
QMessageBox::warning(this, tr("Write File"), tr("Cannot open file:\n%1").arg(path));
return;
}
QTextStream out(&file);
out << textEdit->toPlainText();
file.close();
} else {
QMessageBox::warning(this, tr("Path"), tr("You did not select any file."));
}
}
