Qt：QNetworkReply

0、说明

QNetworkReply对象包含了Manager发送的请求头和返回的数据。

它继承自QIODevice，所以可以用各种read获取其中返回的数据：

QByteArray data = reply->readAll();

QNetworkReply是顺序访问的QIODevice，这意味着一旦数据从中读取出来之后，它就不再为Device保存了。因此保存数据的工作必须要由应用程序自己来实现。每当有新的数据从网络中传来时，readyRead()信号就会被发送。

此外，数据接收时downloadProgress()信号也会被发送，只是其中包含的bytes数并不代表实际接收的bytes，因为可能存在着数据转换（如解压缩和撤销协议）。

它也会发送uploadProgress()信号，指示上传这些内容的进度。

注意

不要在信号errorOccurred()和finished()的槽中删除Object，而应该使用deleteLater()。

1、模块和加载项

Header:	#include <QNetworkReply>
qmake:	QT += network
Since:	Qt 4.4
Inherits:	QIODevice

2、构造

无

3、静态字段

类型	字段	说明
enum	NetworkError	标识在处理Request期间可能发生的所有错误。 常见的是QNetworkReply::NoError，标识没有错误。
typedef	RawHeaderPair	一个QPair < QByteArray , QByteArray >，第一个QByteArray是header name，第二个QByteArray是header

NetworkError

Constant	Value	Description
QNetworkReply::ConnectionRefusedError	1	the remote server refused the connection (the server is not accepting requests)
QNetworkReply::RemoteHostClosedError	2	the remote server closed the connection prematurely, before the entire reply was received and processed
QNetworkReply::HostNotFoundError	3	the remote host name was not found (invalid hostname)
QNetworkReply::TimeoutError	4	the connection to the remote server timed out
QNetworkReply::OperationCanceledError	5	the operation was canceled via calls to abort() or close() before it was finished.
QNetworkReply::SslHandshakeFailedError	6	the SSL/TLS handshake failed and the encrypted channel could not be established. The sslErrors() signal should have been emitted.
QNetworkReply::TemporaryNetworkFailureError	7	the connection was broken due to disconnection from the network, however the system has initiated roaming to another access point. The request should be resubmitted and will be processed as soon as the connection is re-established.
QNetworkReply::NetworkSessionFailedError	8	the connection was broken due to disconnection from the network or failure to start the network.
QNetworkReply::BackgroundRequestNotAllowedError	9	the background request is not currently allowed due to platform policy.
QNetworkReply::TooManyRedirectsError	10	while following redirects, the maximum limit was reached. The limit is by default set to 50 or as set by QNetworkRequest::setMaxRedirectsAllowed(). (This value was introduced in 5.6.)
QNetworkReply::InsecureRedirectError	11	while following redirects, the network access API detected a redirect from a encrypted protocol (https) to an unencrypted one (http). (This value was introduced in 5.6.)
QNetworkReply::ProxyConnectionRefusedError	101	the connection to the proxy server was refused (the proxy server is not accepting requests)
QNetworkReply::ProxyConnectionClosedError	102	the proxy server closed the connection prematurely, before the entire reply was received and processed
QNetworkReply::ProxyNotFoundError	103	the proxy host name was not found (invalid proxy hostname)
QNetworkReply::ProxyTimeoutError	104	the connection to the proxy timed out or the proxy did not reply in time to the request sent
QNetworkReply::ProxyAuthenticationRequiredError	105	the proxy requires authentication in order to honour the request but did not accept any credentials offered (if any)
QNetworkReply::ContentAccessDenied	201	the access to the remote content was denied (similar to HTTP error 403)
QNetworkReply::ContentOperationNotPermittedError	202	the operation requested on the remote content is not permitted
QNetworkReply::ContentNotFoundError	203	the remote content was not found at the server (similar to HTTP error 404)
QNetworkReply::AuthenticationRequiredError	204	the remote server requires authentication to serve the content but the credentials provided were not accepted (if any)
QNetworkReply::ContentReSendError	205	the request needed to be sent again, but this failed for example because the upload data could not be read a second time.
QNetworkReply::ContentConflictError	206	the request could not be completed due to a conflict with the current state of the resource.
QNetworkReply::ContentGoneError	207	the requested resource is no longer available at the server.
QNetworkReply::InternalServerError	401	the server encountered an unexpected condition which prevented it from fulfilling the request.
QNetworkReply::OperationNotImplementedError	402	the server does not support the functionality required to fulfill the request.
QNetworkReply::ServiceUnavailableError	403	the server is unable to handle the request at this time.
QNetworkReply::ProtocolUnknownError	301	the Network Access API cannot honor the request because the protocol is not known
QNetworkReply::ProtocolInvalidOperationError	302	the requested operation is invalid for this protocol
QNetworkReply::UnknownNetworkError	99	an unknown network-related error was detected
QNetworkReply::UnknownProxyError	199	an unknown proxy-related error was detected
QNetworkReply::UnknownContentError	299	an unknown error related to the remote content was detected
QNetworkReply::ProtocolFailure	399	a breakdown in protocol was detected (parsing error, invalid or unexpected responses, etc.)
QNetworkReply::UnknownServerError	499	an unknown error related to the server response was detected

4、实例方法

返回值类型	方法	说明
QVariant	attribute(QNetworkRequest::Attribute code)
QNetworkReply::NetworkError	error()
bool	hasRawHeader(QByteArray headerName)
QVariant	header(QNetworkRequest::KnownHeaders header)
void	ignoreSslErrors(QList<QSslError> errors)
bool	isFinished()
bool	isRunning()
QNetworkAccessManager *	manager()
QNetworkAccessManager::Operation	operation()
QByteArray	rawHeader(QByteArray headerName)
QList<QByteArray>	rawHeaderList()
QList<QNetworkReply::RawHeaderPair>	rawHeaderPairs()
qint64	readBufferSize()
QNetworkRequest	request()
virtual void	setReadBufferSize(qint64 size)
void	setSslConfiguration(QSslConfiguration config)
QSslConfiguration	sslConfiguration()
QUrl	url()

5、信号

信号	说明
downloadProgress(qint64 bytesReceived, qint64 bytesTotal)
encrypted()
errorOccurred(QNetworkReply::NetworkError code)
finished()
metaDataChanged()
preSharedKeyAuthenticationRequired(QSslPreSharedKeyAuthenticator *authenticator)
redirectAllowed()
redirected(QUrl url)
sslErrors(QList<QSslError> errors)
uploadProgress(qint64 bytesSent, qint64 bytesTotal)