QT文件读取

1：使用QT的文件IO QFile 和 QFileDialog文件对话框，读取一个选中的文件，然后使用QSlider显示读取的进度，QSlider需要改成进度条的样式

mythread.h

#ifndef MYTHREAD_H
#define MYTHREAD_H

#include <QThread>
#include <QObject>

class mythread : public QThread
{
    Q_OBJECT
public:
    mythread(QObject *parent = Q_NULLPTR);

protected:
    virtual void run() override;

signals:
    void sndSig();
};

#endif // MYTHREAD_H

mthread.cpp

#include "mythread.h"

mythread::mythread(QObject *parent)
    :QThread(parent)
{

}

void mythread::run()
{
    while (1) {
        emit sndSig();
        this->msleep(50);
    }
}

widget.h

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <QComboBox>
#include <QSlider>
#include <QString>
#include <QTimer>
#include "mythread.h"
#include <QFileDialog>
#include <QDebug>
#include <QProgressBar>
#include <QMessageBox>

QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACE

class Widget : public QWidget
{
    Q_OBJECT

public:
    Widget(QWidget *parent = nullptr);
    ~Widget();

public slots:
    void readslot();
    void startslot();

private slots:
    void on_pushButton_clicked();

signals:
    void trigger();

private:
    Ui::Widget *ui;
    QTimer* timer;
    int i = 0;
    mythread* t;
    QFile* fd;
    QByteArray btarr;
    qint64 maxsize=1024;
    qint64 size=0;
    void readFileInChunks(const QString &content);

};
#endif // WIDGET_H

widget.cpp

#include "widget.h"
#include "ui_widget.h"

Widget::Widget(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::Widget)
{
    ui->setupUi(this);
    ui->slider->setRange(1,100);

    //设置按钮
    QString qss = "QPushButton{background-color:black;color:red}QPushButton:hover{background-color:green}";
    ui->pushButton->setStyleSheet(qss);

    //设置下拉栏
    QString qss1 = "QComboBox::drop-down{image:url(C:/Users/11214/Desktop/mn.jpg)}";
    ui->comboBox->setStyleSheet(qss1);

    //设置滑动条
    QString qss2 = "QSlider::sub-page:horizontal{background-color:rgb(0,255,0)}\
                    QSlider::groove:horizontal{background-color:lightgray}";
    ui->slider->setStyleSheet(qss2);

    //创建线程
    t = new mythread(this);

    QObject::connect(t,&mythread::sndSig,this,&Widget::readslot);
    QObject::connect(this,&Widget::trigger,this,&Widget::startslot);
}

Widget::~Widget()
{

    t->terminate();
    delete ui;
}

//点击按钮触发文件对话框
void Widget::on_pushButton_clicked()
{
    QString fileName = QFileDialog::getOpenFileName(this,"打开文件","D:/qt.img","Text Files (*.*);;All Files (*)");
    if(fileName.isEmpty()){
        return;
    }else{
        emit trigger();

        //QFile设置文件名
        fd = new QFile(fileName);

        //打开文件
        fd->open(QIODevice::ReadOnly);

        //将进度条的范围设置为文件的大小
        ui->slider->setRange(0,fd->size());
    }
}

void Widget::startslot()
{
   t->start();
}


void Widget::readslot()
{
    btarr = fd->read(maxsize);
    size += maxsize;

    //进度条随读取增长
    ui->slider->setValue(size);

    if(size >= fd->size()){
        qDebug() << "读取完毕";

        fd->close();
        size = 0;
        //关闭线程
        t->terminate();
    }