QT5网络相关(QNetworkAccessManager)

QNetworkAccessManager类允许应用程序发送网络请求和接收网络应答。

先来两个官方文档中的例子

1.

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

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

2.

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

QNetworkReply *reply = manager->get(request);
connect(reply, SIGNAL(readyRead()), this, SLOT(slotReadyRead()));
connect(reply, SIGNAL(error(QNetworkReply::NetworkError)),
        this, SLOT(slotError(QNetworkReply::NetworkError)));
connect(reply, SIGNAL(sslErrors(QList<QSslError>)),
        this, SLOT(slotSslErrors(QList<QSslError>)));

一般访问网页获取数据用第一个，而下载普通URL文件用第二个，下面举例说明

1.访问网页

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

QString URL = "http://www.baidu.com";
/*URL.append("/...");追加数据*/
manager->get(QNetworkRequest(QUrl(URL)));

void MainWindow::replyFinished(QNetworkReply *reply)
{
    QVariant status_code = reply->attribute(QNetworkRequest::HttpStatusCodeAttribute);

    if(reply->error() == QNetworkReply::NoError)
    {
        QByteArray bytes = reply->readAll();
        QString HTML(bytes);
        //qDebug()<<HTML;
    }
}

2.下载文件

QFile *file = new QFile("test.zip");
    if(!file->open(QIODevice::WriteOnly))
    {
        //qDebug()<<"文件打开出错";
        delete file;
	file = 0;
        return;
    }
    startRequest(url);

void MainWindow::startRequest(QUrl url)
{
    reply = manager->get(QNetworkRequest(url));
    connect(reply,SIGNAL(readyRead()),this,SLOT(readyRead()));
    connect(reply,SIGNAL(downloadProgress(qint64,qint64)),this,SLOT(updateProgress(qint64,qint64)));//更新进度条
    connect(reply,SIGNAL(finished()),this,SLOT(finished()));//下载完成
}

void MainWindow::readyRead()
{
    if(file)
        file->write(reply->readAll());
}

void MainWindow::updateProgress(qint64 bytesRead, qint64 totalBytes)
{
    ui->progressBar->setMaximum(totalBytes);
    ui->progressBar->setValue(bytesRead);
}

void MainWindow::finished()
{
    file->flush();
    file->close();
    reply->deleteLater();
    reply = 0;
    delete file;
    file = 0;
    //qDebug()<<"下载完成";
}

3.如果需要代理ip则可通过以下方法设置

QNetworkProxy proxy;
proxy.setHostName("代理ip");
proxy.setPort("端口");
proxy.setType(QNetworkProxy::HttpProxy);
manager->setProxy(proxy);

详情参考官方文档