添加多线程下载示例

MultiplethreadDownload/.gitignore

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+# This file is used to ignore files which are generated
+# ----------------------------------------------------------------------------
+
+*~
+*.autosave
+*.a
+*.core
+*.moc
+*.o
+*.obj
+*.orig
+*.rej
+*.so
+*.so.*
+*_pch.h.cpp
+*_resource.rc
+*.qm
+.#*
+*.*#
+core
+!core/
+tags
+.DS_Store
+.directory
+*.debug
+Makefile*
+*.prl
+*.app
+moc_*.cpp
+ui_*.h
+qrc_*.cpp
+Thumbs.db
+*.res
+*.rc
+/.qmake.cache
+/.qmake.stash
+
+# qtcreator generated files
+*.pro.user*
+
+# xemacs temporary files
+*.flc
+
+# Vim temporary files
+.*.swp
+
+# Visual Studio generated files
+*.ib_pdb_index
+*.idb
+*.ilk
+*.pdb
+*.sln
+*.suo
+*.vcproj
+*vcproj.*.*.user
+*.ncb
+*.sdf
+*.opensdf
+*.vcxproj
+*vcxproj.*
+
+# MinGW generated files
+*.Debug
+*.Release
+
+# Python byte code
+*.pyc
+
+# Binaries
+# --------
+*.dll
+*.exe
+

MultiplethreadDownload/MultiplethreadDownload.pro

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+QT       += core gui network concurrent
+
+greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
+
+CONFIG += c++17
+
+# You can make your code fail to compile if it uses deprecated APIs.
+# In order to do so, uncomment the following line.
+#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0
+
+SOURCES += \
+    main.cpp \
+    utils.cpp \
+    widget.cpp
+
+HEADERS += \
+    utils.h \
+    widget.h
+
+FORMS += \
+    widget.ui
+
+# Default rules for deployment.
+qnx: target.path = /tmp/$${TARGET}/bin
+else: unix:!android: target.path = /opt/$${TARGET}/bin
+!isEmpty(target.path): INSTALLS += target

MultiplethreadDownload/main.cpp

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+#include "widget.h"
+
+#include <QApplication>
+#include <QScreen>
+
+int main(int argc, char *argv[])
+{
+    QApplication a(argc, argv);
+    Widget w;
+    w.show();
+    w.move(QApplication::screens().at(0)->geometry().center() - w.frameGeometry().center());
+    return a.exec();
+}

MultiplethreadDownload/utils.cpp

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+#include "utils.h"
+#include <QStringList>
+#include <QLocale>
+
+
+QString Utils::sizeFormat(qint64 bytes)
+{
+    qreal size = bytes;
+    QStringList list;
+    list << "KB" << "MB" << "GB" << "TB";
+
+    QStringListIterator i(list);
+    QString unit("bytes");
+
+    while (size >= 1024.0 && i.hasNext()) {
+        unit = i.next();
+        size /= 1024.0;
+    }
+    return QString().setNum(size, 'f', 2) + " " + unit;
+}
+

MultiplethreadDownload/utils.h

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+#ifndef UTILS_H
+#define UTILS_H
+
+#include <QtGlobal>
+
+class Utils
+{
+public:
+    static QString sizeFormat(qint64 bytes);
+};
+
+#endif // UTILS_H

MultiplethreadDownload/widget.cpp

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+#include "widget.h"
+#include "ui_widget.h"
+#include "utils.h"
+#include <QUrl>
+#include <QNetworkReply>
+#include <QNetworkRequest>
+#include <QMessageBox>
+#include <QRegExp>
+#include <QRegExpValidator>
+#include <QFileDialog>
+#include <QDir>
+#include <QThread>
+#include <QEventLoop>
+#include <QFuture>
+#include <QtConcurrent/QtConcurrent>
+
+Widget::Widget(QWidget *parent)
+    : QWidget(parent)
+    , ui(new Ui::Widget)
+{
+    ui->setupUi(this);
+
+    // 设置URL链接验证器
+    QRegExp regex(R"(http[s]://.+)");
+    auto *validator = new QRegExpValidator(regex, nullptr);
+    ui->urlInput->setValidator(validator);
+
+    // 设置最大的线程并发数
+    int processer_num = QThread::idealThreadCount();
+    processer_num = processer_num > maxThreadNum ? maxThreadNum : processer_num;
+    ui->threadCountSpinbox->setMaximum(processer_num);
+    ui->threadCountSpinbox->setValue(processer_num);
+
+    // 设置保存路径为当前程序运行路径
+    ui->savePathInput->setText(QDir::currentPath());
+
+    requestManager = new QNetworkAccessManager(this);
+}
+
+Widget::~Widget()
+{
+    delete ui;
+}
+
+
+/**
+ * @brief 展示错误信息
+ * @param msg
+ */
+void Widget::showError(const QString& msg)
+{
+    auto msgBox = new QMessageBox(this);
+    msgBox->setWindowTitle(tr("请求出错"));
+    msgBox->setIcon(QMessageBox::Critical);
+    msgBox->setText(msg);
+    msgBox->exec();
+    ui->downloadBtn->setEnabled(true);
+}
+
+/**
+ * @brief 获取要下载的文件大小
+ * @param url
+ */
+qint64 Widget::getFileSize(const QString& url)
+{
+    QEventLoop event;
+    QNetworkRequest request;
+    request.setUrl(QUrl(url));
+    request.setAttribute(QNetworkRequest::FollowRedirectsAttribute, true);
+    QNetworkReply *reply = requestManager->head(request);
+    connect(reply, &QNetworkReply::errorOccurred, [this, reply](QNetworkReply::NetworkError error){
+        if (error != QNetworkReply::NoError) {
+            return showError(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();
+    }
+    reply->deleteLater();
+    return fileSize;
+}
+
+
+/**
+ * @brief 开始下载文件
+ * @param url
+ * @param filename
+ */
+void Widget::singleDownload(const QString& url, const QString& filename)
+{
+    QFile file(filename);
+    if (file.exists())
+        file.remove();
+    if (!file.open(QIODevice::WriteOnly)) {
+        return showError(file.errorString());
+    }
+
+    QEventLoop event;
+    QNetworkAccessManager mgr;
+    QNetworkRequest request;
+    request.setUrl(QUrl(url));
+    request.setAttribute(QNetworkRequest::FollowRedirectsAttribute, true);
+    QNetworkReply *reply = mgr.get(request);
+    connect(reply, &QNetworkReply::readyRead, this, [&file, reply](){
+        file.write(reply->readAll());
+    });
+    connect(reply, &QNetworkReply::finished, &event, &QEventLoop::quit);
+    connect(reply, &QNetworkReply::errorOccurred,  [this, reply](QNetworkReply::NetworkError error){
+        if (error != QNetworkReply::NoError) showError(reply->errorString());
+    });
+    event.exec();
+    file.flush();
+    file.close();
+    ui->downloadBtn->setEnabled(true);
+}
+
+/**
+ * @brief 多线程下载
+ * @param url
+ * @param fileSize
+ * @param filename
+ * @param threadCount
+ */
+void Widget::multiDownload(const QString &url, qint64 fileSize, const QString &filename, int threadCount)
+{
+    QFile file(filename);
+    if (file.exists())
+        file.remove();
+    if (!file.open(QIODevice::WriteOnly)) {
+        return showError(file.errorString());
+    }
+    file.resize(fileSize);
+
+    // 任务等分
+    qint64 segmentSize = fileSize / threadCount;
+    QVector<QPair<qint64, qint64>> vec(threadCount);
+    for (int i = 0; i < threadCount; i++) {
+        vec[i].first = i * segmentSize;
+        vec[i].second = i * segmentSize + segmentSize - 1;
+    }
+    vec[threadCount-1].second = fileSize; // 余数部分加入最后一个
+
+    qint64 bytesReceived = 0; // 下载接收的总字节数
+    // 任务队列
+    auto mapCaller = [&, this](const QPair<qint64, qint64>& pair) -> qint64 {
+        QEventLoop event;
+        QNetworkAccessManager mgr;
+        QNetworkRequest request;
+        request.setUrl(url);
+        request.setAttribute(QNetworkRequest::FollowRedirectsAttribute, true);
+        request.setRawHeader("Range", QString("bytes=%1-%2").arg(pair.first).arg(pair.second).toLocal8Bit());
+        QNetworkReply *reply = mgr.get(request);
+        qint64 writePos = pair.first;
+        connect(reply, &QNetworkReply::readyRead, [&, reply, this](){
+            QByteArray data = reply->readAll();
+            lock.lock();
+            file.peek(writePos);
+            file.write(data);
+            bytesReceived += data.size();
+            lock.unlock();
+            writePos += data.size();
+        });
+        connect(reply, &QNetworkReply::finished, &event, &QEventLoop::quit);
+        event.exec();
+        return writePos - pair.first;
+    };
+    QFuture<void> future = QtConcurrent::map(vec, mapCaller);
+    QFutureWatcher<void> futureWatcher;
+    QEventLoop loop;
+    connect(&futureWatcher, &QFutureWatcher<void>::finished, &loop,  &QEventLoop::quit, Qt::QueuedConnection);
+    futureWatcher.setFuture(future);
+    if (!future.isFinished()) {
+        loop.exec();
+    }
+    file.close();
+    qDebug() << "下载完毕！！";
+    ui->downloadBtn->setEnabled(true);
+}
+
+/**
+ * @brief  点击开始下载
+ */
+void Widget::on_downloadBtn_clicked()
+{
+    QString url = ui->urlInput->text().trimmed();
+    if (url.isEmpty()) {
+        return showError(tr("请求链接不允许为空！"));
+        return ;
+    }
+
+    // 选择保存路径
+    QString savePath = ui->savePathInput->text().trimmed();
+    if (savePath.isEmpty()) {
+        savePath = QFileDialog::getExistingDirectory();
+        if (savePath.isEmpty()) return;
+    } else {
+        if(!QDir(savePath).exists()) {
+            return showError(tr("路径不存在！"));
+        }
+    }
+
+    qint64 fileSize = getFileSize(url);
+    QString sizeText = fileSize == 0 ? "未知大小" : Utils::sizeFormat(fileSize);
+    ui->filesizeLabel->setText(sizeText);
+    ui->downloadBtn->setEnabled(false);
+
+    int process_num = ui->threadCountSpinbox->text().toInt();
+
+    QDir::setCurrent(savePath);
+    QString filename = QFileInfo(url).fileName();
+    if (fileSize == 0 || process_num == 1) {
+        singleDownload(url, filename);
+    } else {
+        multiDownload(url, fileSize, filename, process_num);
+    }
+}
+
+/**
+ * @brief 设置保存下载文件的路径
+ */
+void Widget::on_brwoserPathBtn_clicked()
+{
+    QString savePath = QFileDialog::getExistingDirectory();
+    if (!savePath.isEmpty()) {
+        ui->savePathInput->setText(savePath);
+    }
+}
+
+void Widget::download_progress_change(qint64 bytesReceived, qint64 bytesTotal)
+{
+    if (bytesTotal <= 0)
+        return;
+    ui->downProgressBar->setMaximum(10000); // 最大值
+    ui->downProgressBar->setValue((bytesReceived * 10000) / bytesTotal); // 当前值
+    ui->downProgressBar->setTextVisible(true);
+}

MultiplethreadDownload/widget.h

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+#ifndef WIDGET_H
+#define WIDGET_H
+
+#include <QWidget>
+#include <QNetworkAccessManager>
+#include <QMutex>
+
+QT_BEGIN_NAMESPACE
+namespace Ui { class Widget; }
+QT_END_NAMESPACE
+
+class Widget : public QWidget
+{
+    Q_OBJECT
+
+public:
+    Widget(QWidget *parent = nullptr);
+    ~Widget();
+
+protected:
+    void showError(const QString& msg);
+    qint64 getFileSize(const QString& url);
+    void singleDownload(const QString& url, const QString& filename);
+    void multiDownload(const QString& url, qint64 fileSize, const QString& filename, int threadCount);
+
+
+private slots:
+    void on_downloadBtn_clicked();
+    void on_brwoserPathBtn_clicked();
+    void download_progress_change(qint64 bytesReceived, qint64 bytesTotal);
+
+private:
+    QNetworkAccessManager *requestManager;
+    const int maxThreadNum = 8;
+    QMutex lock;
+
+    Ui::Widget *ui;
+};
+#endif // WIDGET_H

MultiplethreadDownload/widget.ui

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+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>Widget</class>
+ <widget class="QWidget" name="Widget">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>635</width>
+    <height>209</height>
+   </rect>
+  </property>
+  <property name="sizePolicy">
+   <sizepolicy hsizetype="Preferred" vsizetype="Preferred">
+    <horstretch>0</horstretch>
+    <verstretch>0</verstretch>
+   </sizepolicy>
+  </property>
+  <property name="maximumSize">
+   <size>
+    <width>16777215</width>
+    <height>209</height>
+   </size>
+  </property>
+  <property name="windowTitle">
+   <string>多线程下载文件Demo</string>
+  </property>
+  <layout class="QVBoxLayout" name="verticalLayout">
+   <property name="sizeConstraint">
+    <enum>QLayout::SetDefaultConstraint</enum>
+   </property>
+   <item>
+    <layout class="QGridLayout" name="gridLayout">
+     <item row="0" column="0">
+      <widget class="QLabel" name="label">
+       <property name="text">
+        <string>URL:</string>
+       </property>
+      </widget>
+     </item>
+     <item row="0" column="1">
+      <widget class="QLineEdit" name="urlInput"/>
+     </item>
+     <item row="0" column="2">
+      <widget class="QPushButton" name="downloadBtn">
+       <property name="text">
+        <string>下载</string>
+       </property>
+      </widget>
+     </item>
+     <item row="1" column="0">
+      <widget class="QLabel" name="label_2">
+       <property name="text">
+        <string>保存路径:</string>
+       </property>
+      </widget>
+     </item>
+     <item row="1" column="1">
+      <widget class="QLineEdit" name="savePathInput"/>
+     </item>
+     <item row="1" column="2">
+      <widget class="QPushButton" name="brwoserPathBtn">
+       <property name="text">
+        <string>浏览</string>
+       </property>
+      </widget>
+     </item>
+     <item row="2" column="0">
+      <widget class="QLabel" name="label_3">
+       <property name="text">
+        <string>原始线程数：</string>
+       </property>
+      </widget>
+     </item>
+     <item row="2" column="1">
+      <widget class="QSpinBox" name="threadCountSpinbox">
+       <property name="minimum">
+        <number>1</number>
+       </property>
+       <property name="value">
+        <number>1</number>
+       </property>
+      </widget>
+     </item>
+     <item row="2" column="2">
+      <widget class="QPushButton" name="pauseBtn">
+       <property name="text">
+        <string>暂停</string>
+       </property>
+      </widget>
+     </item>
+     <item row="3" column="0">
+      <widget class="QLabel" name="label_4">
+       <property name="text">
+        <string>下载进度：</string>
+       </property>
+      </widget>
+     </item>
+     <item row="3" column="1">
+      <widget class="QProgressBar" name="downProgressBar">
+       <property name="value">
+        <number>0</number>
+       </property>
+       <property name="textVisible">
+        <bool>false</bool>
+       </property>
+       <property name="textDirection">
+        <enum>QProgressBar::TopToBottom</enum>
+       </property>
+      </widget>
+     </item>
+     <item row="3" column="2">
+      <widget class="QCheckBox" name="dwnFinishedOpenChbox">
+       <property name="text">
+        <string>下载完成是否打开</string>
+       </property>
+      </widget>
+     </item>
+    </layout>
+   </item>
+   <item>
+    <layout class="QHBoxLayout" name="horizontalLayout">
+     <item>
+      <widget class="QLabel" name="label_5">
+       <property name="text">
+        <string>下载速度：</string>
+       </property>
+      </widget>
+     </item>
+     <item>
+      <widget class="QLabel" name="downloadSpeedLabel">
+       <property name="text">
+        <string/>
+       </property>
+      </widget>
+     </item>
+     <item>
+      <widget class="QLabel" name="label_7">
+       <property name="text">
+        <string>文件大小：</string>
+       </property>
+      </widget>
+     </item>
+     <item>
+      <widget class="QLabel" name="filesizeLabel">
+       <property name="text">
+        <string/>
+       </property>
+      </widget>
+     </item>
+    </layout>
+   </item>
+  </layout>
+ </widget>
+ <resources/>
+ <connections/>
+</ui>

README.md

@@ -9,3 +9,11 @@
 
 ![](./QProxyStyleTest/screenshot.png)
 
+## 多线程下载
+[MultiplethreadDownload](./MultiplethreadDownload/)         
+
+测试视频下载地址 https://www.learningcontainer.com/wp-content/uploads/2020/05/sample-mp4-file.mp4       
+下完的文件好像是有问题的。。。。请帮忙看一下        
+
+参考内容        
+* CoverEars(迅雷不及掩耳，Qt版多线程下载器) https://github.com/xj361685640/CoverEars-Qt