如何通过QNetworkAccessManager发送用于post的有效负载？

QNetworkAccessManager *manager = new QNetworkAccessManager(this);

QNetworkRequest request;
request.setUrl(QUrl("http://example.com/api"));
request.setHeader(QNetworkRequest::ContentTypeHeader, "application/json");

QJsonObject payload;
payload["key1"] = "value1";
payload["key2"] = "value2";
QJsonDocument payloadDoc(payload);
QByteArray payloadData = payloadDoc.toJson();

QNetworkReply *reply = manager->post(request, payloadData);

connect(reply, &QNetworkReply::finished, this, [=]() {
    if (reply->error() == QNetworkReply::NoError) {
        QByteArray responseData = reply->readAll();
        // 处理响应数据
    } else {
        // 处理错误
    }
    reply->deleteLater();
});