Qt5中创建临时的后台线程。

有个需求就是，GUI图形界面在上传文件到服务器的时候，需要用zip命令行打包，因为文件很多的时候，zip命令打包需要计算很长时间，所以把这样计算量大的任务分离到后台线程比较合适，然后任务完成，以信号槽机制来通知前台

UI线程处理结果。所以这个线程是需要销毁的，跟之前的一直在运行的后台线程接收网络数据的不一样。

压缩文件的任务类  H文件：

 #include <QObject>
 #include <QStringList>

 class ZipUpdatePackageTask : public QObject
 {
     Q_OBJECT

 public:
     ZipUpdatePackageTask();
     ~ZipUpdatePackageTask();

 public slots:
     void doZip();
     void beZipFiles(const QStringList& files);
 signals:
     void zipFinished();
     void zipPackageInfo(const QString& fileName, const QString& md5, const QString& size);

 private:
     bool beZipFilesIsEmpty();
     void deleteHistoryZip(const QString& targetPackage);
     void toBeZipFilesArguments(QString &files);
     void startZipTask(QString zipExePath, QString targetPackage, QString files);
     QString getFileMD5(const QString& targetZipPackage);
     QString getFileSize(const QString& targetZipPackage);
 private:
     QStringList m_files;
 };

压缩任务类的 cpp文件：

 #include <QCoreApplication>
 #include <QFile>
 #include <QFileInfo>
 #include <QDir>
 #include <QProcess>
 #include <QCryptographicHash>

 ZipUpdatePackageTask::ZipUpdatePackageTask()
 {
 }

 ZipUpdatePackageTask::~ZipUpdatePackageTask()
 {
 }

 void ZipUpdatePackageTask::doZip()
 {
     QString appDir = qApp->applicationDirPath();
     QString zipExePath = QString("%1/%2").arg(appDir).arg("zip.exe");
     if (QFile::exists(zipExePath) && !beZipFilesIsEmpty())
     {

         QString targetZipPackage = QString("%1/%2").arg(appDir).arg("update.zip");
         QString beZipFiles;

         toBeZipFilesArguments(beZipFiles);
         deleteHistoryZip(targetZipPackage);
         startZipTask(zipExePath, targetZipPackage, beZipFiles);

         if (QFile::exists(targetZipPackage))
         {
             QString size = getFileSize(targetZipPackage);
             QString md5 = getFileMD5(targetZipPackage);

             emit zipPackageInfo(targetZipPackage, md5, size);

         }

     }

     emit zipFinished();
 }

 void ZipUpdatePackageTask::beZipFiles(const QStringList& files)
 {
     m_files.clear();
     m_files = files;
 }

 bool ZipUpdatePackageTask::beZipFilesIsEmpty()
 {
     return m_files.isEmpty();
 }

 void ZipUpdatePackageTask::deleteHistoryZip(const QString& targetPackage)
 {
     if (QFile::exists(targetPackage))
     {
         QDir dir;
         dir.remove(targetPackage);
     }
 }

 void ZipUpdatePackageTask::toBeZipFilesArguments(QString &files)
 {
     for (auto file : m_files)
     {
         files.append(file);
         files.append(" ");
     }
 }

 void ZipUpdatePackageTask::startZipTask(QString zipExePath, QString targetPackage, QString files)
 {
     QProcess* zipProcesss = new QProcess;
     //zip a [zip_package_path_name] [file1Path]...[fileNPath]
     QString command = QString("%1 a %2 %3").arg(zipExePath).arg(targetPackage).arg(files);
     zipProcesss->start(command);
     zipProcesss->waitForFinished(-);
 }

 QString ZipUpdatePackageTask::getFileMD5(const QString& targetZipPackage)
 {
     QString md5;
     QFile file(targetZipPackage);
     if (file.open(QFile::ReadOnly))
     {
         QCryptographicHash hash(QCryptographicHash::Md5);
         if (hash.addData(&file))
         {
             md5 = QString(hash.result().toHex());
         }

         file.close();
     }
     return md5;
 }

 QString ZipUpdatePackageTask::getFileSize(const QString& targetZipPackage)
 {
     QFileInfo fileInf(targetZipPackage);
     return QString::number(fileInf.size());
 }

以下是创建这个后台压缩线程的槽函数，当压缩上传的button点击，就调用以下这个槽函数:

 void StatisticsWidget::slotUploadPackage()
 {
     QThread *zipThread = new QThread;
     ZipUpdatePackageTask* task = new ZipUpdatePackageTask();

     QStringList beZipFiles;
     for (int listRow = ; listRow < ui->updateFileList->count(); ++listRow)
     {
         beZipFiles << ui->updateFileList->item(listRow)->text();
     }

     task->beZipFiles(beZipFiles);
     task->moveToThread(zipThread);

     connect(zipThread, &QThread::started, task, &ZipUpdatePackageTask::doZip);

     connect(task, SIGNAL(zipFinished()), zipThread, SLOT(quit()));
     connect(task, &ZipUpdatePackageTask::zipPackageInfo, this, &StatisticsWidget::slotZipFinished,Qt::QueuedConnection);

     //automatically delete thread and task object when work is done:
     connect(zipThread, SIGNAL(finished()), task, SLOT(deleteLater()));
     connect(zipThread, SIGNAL(finished()), zipThread, SLOT(deleteLater()));
     zipThread->start();
 }

注意，以上代码都是临时任务和线程，当任务完成以后，由于设置了相应的信号槽，会自动删除。 任务线程做完该做的事儿，发出了一个zipPackageInfo的信号就销毁了。UI线程只用编写一个槽函数来接收做完的信号并处理就可以了。