如何使用 QNetworkManager for REST api？

Question

我想制作一个 class 用于通过 REST API 访问数据，例如：

class MeteoStation{
   int getLatestTemperature();
   int getLatestPessure();
   private:
   QNetworkManager nmng;
}

如何实现这些方法？通常我使用的是：

   int MeteoStation::getLatestTemperature(){    
      ...
      QEventLoop eventLoop;
      connect(&m_nam,SIGNAL(finished(QNetworkReply*)),&eventLoop,SLOT(quit()));
      QNetworkReply *reply = m_nam.get( req );
      eventLoop.exec();
      reply->readAll()
      ...
    }

但是由于不推荐使用内部QEventLoop，我应该如何查看响应属于谁？

MeteoStation::MeteoStation(){
   connect(&nmam, SIGNAL(finished(QNetworkReply*)),
                     this, SLOT(parseNetworkResponse(QNetworkReply*)));
}

void MeteoStation::parseNetworkResponse( QNetworkReply *finished )
{
   QByteArray data = finished->readAll();
...

是的，保存 class 线程会很好。你是如何在你的代码中解决这个问题的？

使调用同步有多糟糕：

QNetworkRequest req(url);
QScopedPointer<QNetworkReply> reply(nam.get(req));

QTime timeout= QTime::currentTime().addSecs(10);
while( QTime::currentTime() < timeout && !reply->isFinished()){
    QCoreApplication::processEvents(QEventLoop::AllEvents, 100);
}

if (reply->error() != QNetworkReply::NoError) {
    qDebug() << "Failure" <<reply->errorString();
}
QByteArray data = reply->readAll();

Answer 1

Qt 文档应该提供您需要的所有信息。你创建一个名字，连接完成信号，发送请求。

QNetworkAccessManager *manager = new QNetworkAccessManager(this);
connect(manager, SIGNAL(finished(QNetworkReply*)),
        this, SLOT(parseNetworkResponse(QNetworkReply*)));

manager->get(QNetworkRequest(QUrl("http://qt-project.org")));

检测回复属于哪个请求应该不难。回复包含 url。可能不同，但不同：

...but for a variety of reasons it can be different (for example, a file path being made absolute or canonical).

QUrl QNetworkReply::url() const

Returns the URL of the content downloaded or uploaded. Note that the URL may be different from that of the original request.

Answer 2

我已经使用 QCoreApplication::processEvents() 解决了我的问题。响应在 ms 内，我能够实现接近 libcurl 的功能。

QNetworkRequest req(url);
QScopedPointer<QNetworkReply> reply(nam.get(req));

QTime timeout= QTime::currentTime().addSecs(10);
while( QTime::currentTime() < timeout && !reply->isFinished()){
    QCoreApplication::processEvents(QEventLoop::AllEvents, 100);
}

if (reply->error() != QNetworkReply::NoError) {
    qDebug() << "Failure" <<reply->errorString();
}
QByteArray data = reply->readAll();

如何使用 QNetworkManager for REST api？

How to use QNetworkManager for REST api?

c++

rest

qt

network-programming