QNetworkAccessManager Class

Detailed Description

The Network Access API is constructed around one QNetworkAccessManager object, which holds the common configuration and settings for the requests it sends. It contains the proxy and cache configuration, as well as the signals related to such issues, and reply signals that can be used to monitor the progress of a network operation. One QNetworkAccessManager instance should be enough for the whole Qt application. Since QNetworkAccessManager is based on QObject, it can only be used from the thread it belongs to.

Once a QNetworkAccessManager object has been created, the application can use it to send requests over the network. A group of standard functions are supplied that take a request and optional data, and each return a QNetworkReply object. The returned object is used to obtain any data returned in response to the corresponding request.

A simple download off the network could be accomplished with:

 QNetworkAccessManager *manager = new QNetworkAccessManager(this);
 connect(manager, &QNetworkAccessManager::finished,
         this, &MyClass::replyFinished);

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

QNetworkAccessManager has an asynchronous API. When the replyFinished slot above is called, the parameter it takes is the QNetworkReply object containing the downloaded data as well as meta-data (headers, etc.).

A more involved example, assuming the manager is already existent, can be:

 QNetworkRequest request;
 request.setUrl(QUrl("http://qt-project.org"));
 request.setRawHeader("User-Agent", "MyOwnBrowser 1.0");

 QNetworkReply *reply = manager->get(request);
 connect(reply, &QIODevice::readyRead, this, &MyClass::slotReadyRead);
 connect(reply, &QNetworkReply::errorOccurred,
         this, &MyClass::slotError);
 connect(reply, &QNetworkReply::sslErrors,
         this, &MyClass::slotSslErrors);