lv20 QT文件编程6

1 文件普通读写

略

2 流式操作

QFile file("in.txt");
if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
          return;
 
QTextStream in(&file);
while (!in.atEnd()) {
          QString line = in.readLine();
          process_line(line);
      }

示例

widegt.h

#ifndef WIDGET_H
#define WIDGET_H
 
#include <QWidget>
#include <QTextEdit>
#include <QLineEdit>
#include <QPushButton>
#include <QFileDialog>
#include <QTextStream>
 
class Widget : public QWidget
{
    Q_OBJECT
 
public:
    Widget(QWidget *parent = 0);
    ~Widget();
public slots:
    void showfile()
    {
        QString filename = QFileDialog::getOpenFileName();
        le->setText(filename);
#if 0
        QFile file(filename);
        if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
             return;
 
        while (!file.atEnd()) {
             QByteArray line = file.readLine();
            // process_line(line);
             te->append(line);
        }
#endif
        QFile file(filename);
              if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
                  return;
 
              QTextStream in(&file);
              while (!in.atEnd()) {
                  QString line = in.readLine();
                //  process_line(line);
                  te->append(line);
              }
    }
 
private:
    QTextEdit *te;
    QLineEdit *le;
    QPushButton *pb;
};
 
#endif // WIDGET_H

wigdet.cpp

#include "widget.h"
#include <QVBoxLayout>
 
Widget::Widget(QWidget *parent)
    : QWidget(parent)
{
    te = new QTextEdit;
    te->setMinimumSize(640, 480);
    le = new QLineEdit;
    pb = new QPushButton("showtxt");
 
    QVBoxLayout *vbox = new QVBoxLayout;
    vbox->addWidget(te);
    vbox->addWidget(le);
    vbox->addWidget(pb);
    setLayout(vbox);
 
    connect(pb, SIGNAL(clicked(bool)), this, SLOT(showfile()));
    
}
 
Widget::~Widget()
{
 
}

3 文件属性

QFileInfo  info1("/home/bob/bin/untabify");
info1.isSymLink(); // returns true 
info1.absoluteFilePath(); // returns "/home/bob/bin/untabify" info1.size(); // returns 56201 
info1.symLinkTarget(); // returns "/opt/pretty++/bin/untabify" 

 文件夹遍历

QDir dir;
QFileInfoList list = dir.entryInfoList();
 
for (int i = 0; i < list.size(); ++i) {
          QFileInfo fileInfo = list.at(i);
}

main.cpp 

#include <QCoreApplication>
#include <QDir>
#include <QFileInfo>
#include <iostream>
 
int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
 
    QDir dir;
 
    QFileInfoList list = dir.entryInfoList();
    std::cout << "     Bytes Filename" << std::endl;
    for (int i = 0; i < list.size(); ++i) {
 
         QFileInfo fileInfo = list.at(i);
         std::cout << fileInfo.size()<< "\t"<<fileInfo.fileName().toStdString().c_str();
 
         std::cout << std::endl;
    }
 
    return a.exec();
}