线程使用Qt发送http请求

时间:2013-12-18 16:59:23

标签: c++ qt qthread qnetworkaccessmanager qtcore

我正在尝试创建一个线程(HttpWorker),当需要唤醒并发送http请求时。我希望这可以在一个线程中完成。我正在使用Qt实现。

我认为我会这样做的方法是拥有一个类MyHttpWorker,将其移动到另一个线程,连接插槽/信号等。然后在线程启动时,我将使用QNetworkAccessManager来调用get请求。我会在请求发送后使用QWaitCondition暂停线程,每当我需要发送另一个时,我都会恢复该线程。

但是,当我暂停httpworker线程时,根本不会调用FinishedSlot。如果我使用该类简单地调用一个http请求,它执行没有问题。所以问题与QWaitCondition有关(或者只是冻结线程)。

我可以简单地为每个请求创建和销毁一个工作线程和线程,但是我需要发送大量的http请求,所以我认为这种方法过于消耗(创建线程并一遍又一遍地销毁它们)。

我感谢任何帮助。

这是我的代码:

MyHttpWorker.h

#include <QNetworkReply>
#include <QDebug>
#include <QObject>
#include <QNetworkAccessManager>
#include <QThread>
#include <QWaitCondition>
#include <QMutex>    

class MyHttpWorker : public QObject
    {
        Q_OBJECT

        QNetworkAccessManager* nam;        
        QMutex syncPause;
        QWaitCondition pauseCond;        

    public:
        explicit MyHttpWorker(QObject *parent = 0);        
        void MyWake();            
    public slots:        
         void SetTheThread(QThread* thread);
         void MyStart();        
         void finishedSlot(QNetworkReply* reply);            
    };

MyHttpWorker.cpp

MyHttpWorker::MyHttpWorker(QObject *parent) :
    QObject(parent)
{
    nam = new QNetworkAccessManager(this);
    QObject::connect(nam, SIGNAL(finished(QNetworkReply*)), this, SLOT(finishedSlot(QNetworkReply*)));    
}

void MyHttpWorker::finishedSlot(QNetworkReply* reply)
{
    qDebug() << "Finished"; //This slot is never even reached, when i used QWaitCond...
    if (reply->error() == QNetworkReply::NoError)
    {
        QByteArray bytes = reply->readAll();
        QString string(bytes);
        qDebug() << string;
    }else
    {
        qDebug() << reply->errorString();
    }
    reply->deleteLater();
}

void MyHttpWorker::SetTheThread(QThread* thread){
    QObject::connect(thread,SIGNAL(started()),this,SLOT(MyStart()));
}

void MyHttpWorker::MyWake(){    
    pauseCond.wakeAll();
}

void MyHttpWorker::MyStart(){    
    qDebug() << "Start" ; 

    while(true){

        syncPause.lock();    
        qDebug() << "thread waiting...";
        pauseCond.wait(&syncPause);
        qDebug() << "thread resumed.";
        syncPause.unlock();

        //sending the actual request here
        QNetworkRequest myRequest;
        myRequest.setUrl(QUrl("http://www.google.com"));
        nam->get(myRequest);



    }

}

的main.cpp

#include <QCoreApplication>
#include <QThread>
#include <QDebug>
#include <myhttpworker.h>

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

   //create the worker, thread and launch it... (worker is waiting by default)
    MyHttpWorker* worker = new MyHttpWorker;    
    QThread* httpThread = new QThread;    
    worker->SetTheThread(httpThread);
    worker->moveToThread(httpThread);    
    httpThread->start();

   //try and send 5 requests ...
     for(int i=0;i<5;i++){
         qDebug() << "Unpausing";    
         QThread::currentThread()->msleep(1000);    
         worker->MyWake();    
     }

    return a.exec();
}

1 个答案:

答案 0 :(得分:2)

不要创建无限循环,而是让偶数循环处理它:

void MyHttpWorker::MyWake()
{
    QMetaObject::invokeMethod(this,"doSend");
    //send to the event loop
}

// new slot
void MyHttpWorker::doSend(){    
    //sending the actual request here
    QNetworkRequest myRequest;
    myRequest.setUrl(QUrl("http://www.google.com"));
    nam->get(myRequest);
}
//and remove the myStart and all that synchronisation

然后当你想要停止它时,只需向线程发送一个quit。我建议你也将帖子的finished信号连接到deleteLater的{​​{1}}位置