完成并发请求下载

src/downloadworker.cpp

@@ -0,0 +1,234 @@
+#include "downloadworker.h"
+#include <QIODevice>
+#include <QEventLoop>
+#include <QNetworkAccessManager>
+#include <QNetworkRequest>
+#include <QNetworkReply>
+#include <QDebug>
+#include <QThread>
+
+DownloadWorker::DownloadWorker(QObject *parent)
+{
+
+}
+
+void DownloadWorker::setIdentifier(int identifier)
+{
+    this->identifier = identifier;
+}
+
+void DownloadWorker::setParamter(const QString &url, QPair<qint64, qint64> range, QFile *file)
+{
+    this->url = url;
+    this->startPos = range.first;
+    this->endPos = range.second;
+    this->file = file;
+}
+
+qint64 DownloadWorker::getReceivedPos()
+{
+    return receivedPos;
+}
+
+void DownloadWorker::doWork()
+{
+        mgr = new QNetworkAccessManager(this);
+        QNetworkRequest request;
+        request.setUrl(url);
+        request.setAttribute(QNetworkRequest::FollowRedirectsAttribute, true);
+        request.setRawHeader("Range", QString("bytes=%1-%2").arg(startPos)
+                    .arg(endPos).toLocal8Bit());
+        reply = mgr->get(request);
+        qDebug() << "开始下载数据：" << QString(" %1~%2 -> writePos Start %3")
+            .arg(startPos).arg(endPos).arg(receivedPos);
+        connect(reply, static_cast<void(QNetworkReply::*)(QNetworkReply::NetworkError)>(&QNetworkReply::error),
+        [this](QNetworkReply::NetworkError error){
+            if (error != QNetworkReply::NoError) {
+                qDebug() << "出错了：" << reply->errorString();
+            }
+        });
+        connect(reply, &QNetworkReply::finished, mgr, &QNetworkAccessManager::deleteLater);
+        connect(reply, &QNetworkReply::finished, reply, &QNetworkReply::deleteLater);
+        connect(reply, &QNetworkReply::readyRead, this, &DownloadWorker::dataReady);
+        connect(reply, &QNetworkReply::finished, this, &DownloadWorker::slotFinish);
+        connect(reply, &QNetworkReply::downloadProgress, this, &DownloadWorker::handleProcess);
+
+}
+
+void DownloadWorker::doStop()
+{
+    reply->disconnect();
+    reply->aboutToClose();
+    reply->deleteLater();
+    reply = nullptr;
+}
+
+void DownloadWorker::dataReady()
+{
+    QByteArray data = reply->readAll();
+    file->seek(startPos + receivedPos);
+    file->write(data);
+    receivedPos += data.size();
+}
+
+void DownloadWorker::slotFinish()
+{
+    file->flush();
+    qDebug() << "数据块下载完毕：" << QString(" %1~%2 -> writePos Start %3")
+        .arg(startPos).arg(endPos).arg(receivedPos);
+    emit workFinished();
+}
+
+void DownloadWorker::handleProcess(qint64, qint64)
+{
+    emit this->downloadProcess();
+}
+
+
+DownloadController::DownloadController(QObject *parent)
+{
+    this->threadNum = QThread::idealThreadCount() > 4 ? 4 : QThread::idealThreadCount();
+}
+
+DownloadController::~DownloadController()
+{
+    for(int i = 0; i < workers.size(); i++) {
+        workers.at(i)->doStop();
+        workers.at(i)->disconnect();
+        workers.at(i)->deleteLater();
+    }
+    workers.clear();
+}
+
+void DownloadController::setFilename(QString filename)
+{
+    this->filename = filename;
+}
+
+void DownloadController::setThreadNum(int threadNum)
+{
+    this->threadNum = threadNum;
+}
+
+/**
+ * @brief 开始下载
+ */
+void DownloadController::startDownload(const QString &url)
+{
+    // 下载任务等分，计算每个线程的下载数据
+    fileSize = getFileSize(url);
+    if (fileSize == 0) {
+        emit errorOccur("文件大小获取失败");
+        return; 
+    }
+    qint64 segmentSize = fileSize / threadNum;
+    ranges.resize(threadNum);
+    QVector<qint64> receivedBytes;
+    receivedBytes.resize(threadNum);
+    for (int i = 0; i < threadNum; i++) {
+        ranges[i].first = i * segmentSize;
+        ranges[i].second = i * segmentSize + segmentSize - 1;
+        receivedBytes[i] = 0;
+    }
+    ranges[threadNum-1].second = fileSize; // 余数部分加入最后一个
+
+    // 打开文件
+    file = new QFile;
+    file->setFileName(filename);
+    if (file->exists())
+        file->remove();
+    if (!file->open(QIODevice::WriteOnly)) {
+        delete file;
+        file = nullptr;
+        emit errorOccur(file->errorString());
+        return;
+    }
+    file->resize(fileSize);
+
+    // 创建下载线程
+    workers.clear();
+    for(int i = 0; i < ranges.size(); i++) {
+        qDebug() << QString("第%1个下载请求：%2-%3").arg(i).arg(ranges.at(i).first).arg(ranges.at(i).second);
+        auto worker = new DownloadWorker(this);
+        auto range = ranges.at(i);
+        worker->setIdentifier(i);
+        worker->setParamter(url, range, file);
+        workers.append(worker);
+        connect(worker, &DownloadWorker::downloadProcess, this, &DownloadController::handleProcess);
+        connect(worker, &DownloadWorker::workFinished, this, &DownloadController::chunkDownloadFinish);
+        worker->doWork();
+    }
+}
+
+/**
+ * @brief 停止下载
+ */
+void DownloadController::stopDownload()
+{
+    for(int i = 0; i < workers.size(); i++) {
+        workers.at(i)->doStop();
+        workers.at(i)->disconnect();
+        workers.at(i)->deleteLater();
+    }
+    workers.clear();
+//    file->flush();
+    file->close();
+    delete file;
+    file = nullptr;
+}
+
+
+void DownloadController::handleProcess()
+{
+    qint64 bytesReceived = 0;
+    for(int i = 0; i < workers.size(); i++) {
+        bytesReceived += workers.at(i)->getReceivedPos();
+    }
+    qDebug() << QString("下载进度 %1-%2").arg(bytesReceived).arg(fileSize);
+    emit downloadProcess(bytesReceived, fileSize);
+}
+
+void DownloadController::chunkDownloadFinish()
+{
+    finish++;
+    if (finish == threadNum) {
+        file->flush();
+        file->close();
+        delete file;
+        file = nullptr;
+        for(int i = 0; i < workers.size(); i++) {
+            workers.at(i)->doStop();
+            workers.at(i)->disconnect();
+            workers.at(i)->deleteLater();
+        }
+        workers.clear();
+        emit downloadFinished();
+    }
+}
+
+qint64 DownloadController::getFileSize(const QString& url)
+{
+    QEventLoop event;
+    QNetworkAccessManager requestManager;
+    QNetworkRequest request;
+    request.setUrl(QUrl(url));
+    request.setAttribute(QNetworkRequest::FollowRedirectsAttribute, true);
+    QNetworkReply *reply = requestManager.head(request);
+    connect(reply, static_cast<void(QNetworkReply::*)(QNetworkReply::NetworkError)>(&QNetworkReply::error),
+    [this, reply](QNetworkReply::NetworkError error){
+        if (error != QNetworkReply::NoError) {
+            emit errorOccur(reply->errorString());
+        }
+    });
+    connect(reply, &QNetworkReply::finished, &event, &QEventLoop::quit);
+    event.exec();
+    qint64 fileSize = 0;
+    if (reply->rawHeader("Accept-Ranges") == QByteArrayLiteral("bytes")
+            && reply->hasRawHeader(QString("Content-Length").toLocal8Bit())) {
+        fileSize = reply->header(QNetworkRequest::ContentLengthHeader).toUInt();
+    }
+    qDebug() << "文件大小为：" << fileSize;
+    reply->deleteLater();
+    return fileSize;
+}
+