基于QT5的网络图片爬虫

以下是一个基于Qt5的简单网络图片爬虫示例代码。这个爬虫使用Qt的网络模块下载图片，并使用QThreadPool来并发下载图片。

#include <QCoreApplication>
#include <QNetworkAccessManager>
#include <QNetworkRequest>
#include <QNetworkReply>
#include <QFile>
#include <QThreadPool>
#include <QRunnable>
#include <QUrl>
#include <QDebug>
 
class ImageCrawler : public QObject {
    Q_OBJECT
public:
    ImageCrawler(QNetworkAccessManager* manager, const QUrl& url)
        : m_manager(manager), m_url(url) {}
 
    void run() override {
        QNetworkRequest request(m_url);
        QNetworkReply* reply = m_manager->get(request);
        QObject::connect(reply, &QNetworkReply::finished, [this, reply]() {
            if (reply->error() == QNetworkReply::NoError) {
                QFile file(QString("image_%1.jpg").arg(m_imageIndex++));
                if (file.open(QIODevice::WriteOnly)) {
                    file.write(reply->readAll());
                    file.close();
                    qDebug() << "Image saved successfully";
                } else {
                    qDebug() << "Cannot open file for writing";
                }
            } else {
                qDebug() << "Error downloading image:" << reply->errorString();
            }
            reply->deleteLater();
        });
    }
 
signals:
    void finished();
 
private:
    QNetworkAccessManager* m_manager;
    QUrl m_url;
    int m_imageIndex = 0;
};
 
class ImageCrawlerPool : public QObject {
    Q_OBJECT
public:
    ImageCrawlerPool(QNetworkAccessManager* manager, const QList<QUrl>& urls, int threadCount = 4)
        : m_manager(manager), m_urls(urls), m_threadCount(threadCount) {
        QThreadPool::globalInstance()->setMaxThreadCount(m_threadCount);
    }
 
    void startCrawling() {
        for (const QUrl& url : m_urls) {
            ImageCrawler* crawler = new ImageCrawler(m_manager, url);
            QObject::connect(crawler, &ImageCrawler::finished, [crawler]() {
                crawler->deleteLater();
            });
            QThreadPool::globalInstance()->start(crawler);
        }
    }
 
private:
    QNetworkAccessManager* m_manager;
    QList<QUrl> m_urls;
    int m_threadCount;
};
 
int main(int argc, ch