Qt使用隨機(jī)驗(yàn)證碼的實(shí)現(xiàn)示例

更新時(shí)間：2024年01月02日 11:41:13 作者：怎么追摩羯座

有時(shí)候在登錄界面需要驗(yàn)證碼功能,這樣能夠防止被惡意程序攻擊,本文主要介紹了Qt使用隨機(jī)驗(yàn)證碼的實(shí)現(xiàn)示例,具有一定的參考價(jià)值,感興趣的可以了解一下

一、新建項(xiàng)目

創(chuàng)建一個(gè)"Qt Widget Application"項(xiàng)目，基類選擇“QMainWindow”

二、自定義CaptchaLabel類

右擊項(xiàng)目名，選擇"Add New...”

C++ -> C++Class，點(diǎn)擊“Choose”

更改類名CaptchaLabel，添加基類QLabel，點(diǎn)擊“下一步”

默認(rèn)，點(diǎn)擊完成

更改captchalabel.h代碼如下

#ifndef CAPTCHALABEL_H
 
#define CAPTCHALABEL_H
 
#include <QObject>
 
#include <QLabel>
 
class CaptchaLabel : public QLabel
 
{
 
public:
 
    explicit CaptchaLabel(QWidget* parent = nullptr);
 
    //獲取隨機(jī)數(shù)
 
    QString getRandNumber() { return m_randNumber; }
 
    void generateRandNumber(int num = 4);  //生成隨機(jī)數(shù)
 
protected:
    void paintEvent(QPaintEvent *event);  //繪制
 
    void mousePressEvent(QMouseEvent *event);  //鼠標(biāo)按下
 
private:
    QString m_randNumber;  //隨機(jī)數(shù)
 
};
 
#endif // CAPTCHALABEL_H

更改captchalabel.cpp代碼如下

#include "captchalabel.h"
#include <QDebug>
#include <QRandomGenerator>
#include <QTimer>
#include <QPainter>
#include <QTime>
 
CaptchaLabel::CaptchaLabel(QWidget *parent) : QLabel(parent)
{
    this->setMinimumSize(100, 30);  //設(shè)置最小大小
    this->setStyleSheet("background-color:white;");  //白色背景
 
    //隨機(jī)數(shù)種子初始化
    qsrand(QTime(0,0,0).secsTo(QTime::currentTime()));
 
    //生成隨機(jī)數(shù)
    generateRandNumber();
}
 
/**
* @brief CaptchaLabel::generateRandNum 生成隨機(jī)數(shù)，默認(rèn)是四個(gè)數(shù)
* @param num
*/
void CaptchaLabel::generateRandNumber(int num)
{
    m_randNumber.clear();
    for(int i = 0; i < num; i++)
    {
        int num = qrand() % 3;
        if(num == 0)  //數(shù)字
        {
            m_randNumber += QString::number(qrand()%10);
        }
        else if(num == 1)  //大寫(xiě)字母
        {
            int temp = 'A';
            m_randNumber += static_cast<QChar>(temp + qrand()%26);
        }
        else if(num == 2)  //小寫(xiě)字母
        {
            int temp = 'a';
            m_randNumber += static_cast<QChar>(temp + qrand()%26);
        }
    }
}
 
/**
* @brief CaptchaLabel::paintEvent 繪制驗(yàn)證碼
*/
void CaptchaLabel::paintEvent(QPaintEvent *)
{
    QPainter painter(this);
 
    int num = m_randNumber.size();  //幾個(gè)隨機(jī)數(shù)
    int width = this->width();
    int height = this->height();
 
    //設(shè)置字體
    int size = (width/num) < height ? (width/num) : height;
    QFont font;
    font.setPixelSize(size);  //設(shè)置字體大小
    font.setItalic(true);  //設(shè)置字體傾斜
    font.setFamily(QString("楷體"));
    painter.setFont(font);  //若設(shè)置字體加粗，有的隨機(jī)數(shù)會(huì)顯示不全
 
    QPen pen;
    //繪制隨機(jī)數(shù)
    for(int i = 0; i < num; i++)
    {
        pen = QPen(QColor(qrand()%255, qrand()%255, qrand()%255));
        painter.setPen(pen);
 
        int y = (height-5-size) <= 0 ? 0 : (qrand()%(height-5-size));
        QRectF rect(width/num*i, y, width/num, size);
        //painter.drawRect(rect);  //測(cè)試時(shí)，查看矩形的位置及大小
        //在矩形rect中繪制大小為size的隨機(jī)數(shù)
        painter.drawText(rect, Qt::AlignHCenter|Qt::AlignBottom, m_randNumber.at(i));
    }
 
    //繪制干擾點(diǎn)
    for(int i = 0; i < (num*25); i++)
    {
        pen = QPen(QColor(qrand()%256, qrand()%256, qrand()%256));
        painter.setPen(pen);
        painter.drawPoint(qrand()%width, qrand()%height);
    }
 
    //繪制干擾線
    for(int i = 0; i < num; i++)
    {
        pen = QPen(QColor(qrand()%256, qrand()%256, qrand()%256));
        painter.setPen(pen);
        painter.drawLine(qrand()%width, qrand()%height, qrand()%width, qrand()%height);
    }
}
 
/**
 
* @brief CaptchaLabel::mousePressEvent 鼠標(biāo)點(diǎn)擊時(shí)更換隨機(jī)數(shù)
 
* @param event
 
*/
void CaptchaLabel::mousePressEvent(QMouseEvent *event)
 
{
 
    Q_UNUSED(event);
 
    //重新生成驗(yàn)證碼
 
    generateRandNumber();
 
    //實(shí)時(shí)更新
 
    update();
}