Question

我有一个n00b问题，我似乎无法从我的Qt代码发出HTTP GET请求......

以下代码应该起作用：

void MainWindow::requestShowPage(){
    QNetworkAccessManager *manager = new QNetworkAccessManager(this);
    connect(manager,SIGNAL(finished(QNetworkReply*)),this,SLOT(requestReceived(QNetworkReply*)));
manager->get(QNetworkRequest(QUrl("http://google.com")));
}

void MainWindow::requestReceived(QNetworkReply* reply){
    QString replyText;
    replyText.fromAscii(reply->readAll());

    ui->txt_debug->appendPlainText(replyText);
}

但问题是，这不起作用：在requestReceived(QNetworkReply* reply)，replyText似乎为空，reply->error()返回0，reply->errorString()返回“未知错误”。我现在真的不知道该怎么做......

有什么想法吗？

Answer 1

显然存在重定向，这不被视为错误您应该使用回复属性中提供的重定向URL运行新请求，直到获得真实页面：

void MainWindow::requestReceived(QNetworkReply *reply)
{
    reply->deleteLater();

    if(reply->error() == QNetworkReply::NoError) {
        // Get the http status code
        int v = reply->attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt();
        if (v >= 200 && v < 300) // Success
        {
             // Here we got the final reply 
            QString replyText = reply->readAll();
            ui->txt_debug->appendPlainText(replyText);
        } 
        else if (v >= 300 && v < 400) // Redirection
        {
            // Get the redirection url
            QUrl newUrl = reply->attribute(QNetworkRequest::RedirectionTargetAttribute).toUrl();
            // Because the redirection url can be relative, 
            // we have to use the previous one to resolve it 
            newUrl = reply->url().resolved(newUrl);

            QNetworkAccessManager *manager = reply->manager();
            QNetworkRequest redirection(newUrl);
            QNetworkReply *newReply = manager->get(redirection);

            return; // to keep the manager for the next request
        } 
    } 
    else 
    {
        // Error
        ui->txt_debug->appendPlainText(reply->errorString());
    }

    reply->manager()->deleteLater();
}

您还应记录重定向的位置或计算重定向的数量，以避免永无止境的循环。

Answer 2

如果reply->error() = 0，则表示请求成功。事实上，你的代码对我来说似乎是正确的，我唯一能做的就是阅读数据。试试这个：

QByteArray rawData = reply->readAll();
QString textData(rawData);
qDebug() << textData;

在Qt下进行HTTP GET

2 个答案: