我正在尝试使用带有单独线程的 QNetworkAccessManager::get() 下载网页,当我运行程序时,它会随机崩溃(可能是一小时或两小时)。代码示例:
class SpiderThread : public QThread
{
Q_OBJECT
public:
SpiderThread();
void run();
private:
bool _stopped;
};
void SpiderThread::run()
{
while (!_stopped) {
DownloadManager downloadManager();
QUrl u = getOneUrl();
QString content = downloadManager.getContent(u);
// some other code
}
}
QString DownloadManager::getContent(const QUrl &url)
{
QEventLoop loop;
QNetworkAccessManager manager;
QNetworkRequest request(url);
request.setRawHeader("User-Agent", _userAgent.toAscii());
QNetworkReply *reply = manager.get(request);
connect(reply, SIGNAL(finished()),
SLOT(replyFinished()));
connect(reply, SIGNAL(finished()),
&loop, SLOT(quit()));
loop.exec();
if (reply->error() != QNetworkReply::NoError) {
if (reply->isRunning())
reply->abort();
reply->deleteLater();
return QString();
}
int httpCode = reply->attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt();
if (httpCode != 200)
return QString();
QByteArray data = reply->readAll();
reply->deleteLater();
return QString(data);
}
我正在使用 QEventloop 阻止 http 请求,直到它完成,当我运行这些代码时,它总是崩溃并显示错误消息:
纯虚方法调用 在没有活动异常的情况下调用终止
gdb 调试信息:
(gdb) BT #0 0x0000003c0dc30285 in raise () from /lib64/libc.so.6 #1 0x0000003c0dc31d30 in abort () from /lib64/libc.so.6 #2 0x0000003d992bed94 in __gnu_cxx::__verbose_terminate_handler() () 来自 /usr/lib64/libstdc++.so.6 #3 0x0000003d992bce46 在?? () 来自 /usr/lib64/libstdc++.so.6 #4 0x0000003d992bce73 in std::terminate() () from /usr/lib64/libstdc++.so.6 #5 0x0000003d992bd3cf in __cxa_pure_virtual () from /usr/lib64/libstdc++.so.6 #6 0x00002aaaabc3cc35 在 QCoreApplication::postEvent(QObject*, QEvent*, int) () 来自 /usr/local/Trolltech/Qt-4.8.2/lib/libQtCore.so.4 #7 0x00002aaaabc5301d in QMetaObject::activate(QObject*, QMetaObject const*, int, void**) () 来自 /usr/local/Trolltech/Qt-4.8.2/lib/libQtCore.so.4 #8 0x00002aaaab7b81a1 在?? () 来自 /usr/local/Trolltech/Qt-4.8.2/lib/libQtNetwork.so.4 #9 0x00002aaaab7ac3ad 在?? () 来自 /usr/local/Trolltech/Qt-4.8.2/lib/libQtNetwork.so.4 #10 0x00002aaaab7c8d1d 在 ?? () 来自 /usr/local/Trolltech/Qt-4.8.2/lib/libQtNetwork.so.4 #11 0x00002aaaab7cadb0 在 ?? () 来自 /usr/local/Trolltech/Qt-4.8.2/lib/libQtNetwork.so.4 #12 0x00002aaaab7a89ce 在 QNetworkAccessManager::createRequest(QNetworkAccessManager::Operation, QNetworkRequest const&, QIODevice*) () 来自 /usr/local/Trolltech/Qt-4.8.2/lib/libQtNetwork.so.4 #13 0x00002aaaab7a5ea4 在 QNetworkAccessManager::get(QNetworkRequest const&) () 来自 /usr/local/Trolltech/Qt-4.8.2/lib/libQtNetwork.so.4 #14 0x00000000004088fe 在 DownloadManager::getContent (this=0x409fff40, url=..., toCodec=...) 在 src/downloadmanager.cpp:55 #15 0x0000000000415248 在 SpiderThread::run (this=0x7ffffffffe2b0) at src/spiderthread.cpp:27 #16 0x00002aaaabb2c3b9 在?? () 来自 /usr/local/Trolltech/Qt-4.8.2/lib/libQtCore.so.4 #17 0x0000003c0e40677d in start_thread () from /lib64/libpthread.so.0 #18 0x0000003c0dcd325d in clone () from /lib64/libc.so.6
请帮助我,我花了这么多时间来找出问题所在,但它仍然不起作用。我犯了一些错误?