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体现读取的进度，QSlider必要改成进度条的样式

mythread.h

2. #ifndef MYTHREAD_H
3. #define MYTHREAD_H
5. #include <QThread>
6. #include <QObject>
8. class mythread : public QThread
9. {
10.     Q_OBJECT
11. public:
12.     mythread(QObject *parent = Q_NULLPTR);
14. protected:
15.     virtual void run() override;
17. signals:
18.     void sndSig();
19. };
21. #endif // MYTHREAD_H

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mthread.cpp

2. #include "mythread.h"
4. mythread::mythread(QObject *parent)
5.     :QThread(parent)
6. {
8. }
10. void mythread::run()
11. {
12.     while (1) {
13.         emit sndSig();
14.         this->msleep(50);
15.     }
16. }

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widget.h

2. #ifndef WIDGET_H
3. #define WIDGET_H
5. #include <QWidget>
6. #include <QComboBox>
7. #include <QSlider>
8. #include <QString>
9. #include <QTimer>
10. #include "mythread.h"
11. #include <QFileDialog>
12. #include <QDebug>
13. #include <QProgressBar>
14. #include <QMessageBox>
16. QT_BEGIN_NAMESPACE
17. namespace Ui { class Widget; }
18. QT_END_NAMESPACE
20. class Widget : public QWidget
21. {
22.     Q_OBJECT
24. public:
25.     Widget(QWidget *parent = nullptr);
26.     ~Widget();
28. public slots:
29.     void readslot();
30.     void startslot();
32. private slots:
33.     void on_pushButton_clicked();
35. signals:
36.     void trigger();
38. private:
39.     Ui::Widget *ui;
40.     QTimer* timer;
41.     int i = 0;
42.     mythread* t;
43.     QFile* fd;
44.     QByteArray btarr;
45.     qint64 maxsize=1024;
46.     qint64 size=0;
47.     void readFileInChunks(const QString &content);
49. };
50. #endif // WIDGET_H

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widget.cpp

2. #include "widget.h"
3. #include "ui_widget.h"
5. Widget::Widget(QWidget *parent)
6.     : QWidget(parent)
7.     , ui(new Ui::Widget)
8. {
9.     ui->setupUi(this);
10.     ui->slider->setRange(1,100);
12.     //设置按钮
13.     QString qss = "QPushButton{background-color:black;color:red}QPushButton:hover{background-color:green}";
14.     ui->pushButton->setStyleSheet(qss);
16.     //设置下拉栏
17.     QString qss1 = "QComboBox::drop-down{image:url(C:/Users/11214/Desktop/mn.jpg)}";
18.     ui->comboBox->setStyleSheet(qss1);
20.     //设置滑动条
21.     QString qss2 = "QSlider::sub-page:horizontal{background-color:rgb(0,255,0)}\
22.                     QSlider::groove:horizontal{background-color:lightgray}";
23.     ui->slider->setStyleSheet(qss2);
25.     //创建线程
26.     t = new mythread(this);
28.     QObject::connect(t,&mythread::sndSig,this,&Widget::readslot);
29.     QObject::connect(this,&Widget::trigger,this,&Widget::startslot);
30. }
32. Widget::~Widget()
33. {
35.     t->terminate();
36.     delete ui;
37. }
39. //点击按钮触发文件对话框
40. void Widget::on_pushButton_clicked()
41. {
42.     QString fileName = QFileDialog::getOpenFileName(this,"打开文件","D:/qt.img","Text Files (*.*);;All Files (*)");
43.     if(fileName.isEmpty()){
44.         return;
45.     }else{
46.         emit trigger();
48.         //QFile设置文件名
49.         fd = new QFile(fileName);
51.         //打开文件
52.         fd->open(QIODevice::ReadOnly);
54.         //将进度条的范围设置为文件的大小
55.         ui->slider->setRange(0,fd->size());
56.     }
57. }
59. void Widget::startslot()
60. {
61.    t->start();
62. }
64. void Widget::readslot()
65. {
66.     btarr = fd->read(maxsize);
67.     size += maxsize;
69.     //进度条随读取增长
70.     ui->slider->setValue(size);
72.     if(size >= fd->size()){
73.         qDebug() << "读取完毕";
75.         fd->close();
76.         size = 0;
77.         //关闭线程
78.         t->terminate();
79.     }

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