QHostInfo 类

QHostInfo 类为主机名查找提供静态函数。更多...

头：	#include <QHostInfo>
qmake:	QT += network

所有成员列表，包括继承成员

注意： 此类的所有函数可重入 .

公共类型

enum	HostInfoError { NoError, HostNotFound, UnknownError }

公共函数

	QHostInfo (QHostInfo && other )
	QHostInfo (const QHostInfo & other )
	QHostInfo (int id = -1)
QHostInfo &	operator= (QHostInfo && other )
QHostInfo &	operator= (const QHostInfo & other )
	~QHostInfo ()
QList<QHostAddress>	addresses () const
QHostInfo::HostInfoError	error () const
QString	errorString () const
QString	hostName () const
int	lookupId () const
void	setAddresses (const QList<QHostAddress> & addresses )
void	setError (QHostInfo::HostInfoError error )
void	setErrorString (const QString & str )
void	setHostName (const QString & hostName )
void	setLookupId (int id )
void	swap (QHostInfo & other )

静态公共成员

void	abortHostLookup (int id )
QHostInfo	fromName (const QString & name )
QString	localDomainName ()
QString	localHostName ()
int	lookupHost (const QString & name , QObject * receiver , const char * member )
int	lookupHost (const QString & name , Functor functor )
int	lookupHost (const QString & name , const QObject * context , Functor functor )

详细描述

QHostInfo 查找与主机名关联的 IP 地址，或与 IP 地址关联的主机名。类提供了 2 个静态方便函数：一个异步工作并在找到主机后发射信号，另一个阻塞并返回 QHostInfo 对象。

要异步查找主机的 IP 地址，调用 lookupHost ()，它以主机名或 IP 地址、接收者对象、及槽签名作为自变量并返回 ID。可以中止查找通过调用 abortHostLookup () 采用查找 ID。

范例：

// To find the IP address of qt-project.org
QHostInfo::lookupHost("qt-project.org",
                      this, SLOT(printResults(QHostInfo)));
// To find the host name for 4.2.2.1
QHostInfo::lookupHost("4.2.2.1",
                      this, SLOT(printResults(QHostInfo)));

The slot is invoked when the results are ready. The results are stored in a QHostInfo object. Call addresses () to get the list of IP addresses for the host, and hostName () to get the host name that was looked up.

If the lookup failed, error () returns the type of error that occurred. errorString () gives a human-readable description of the lookup error.

若想要阻塞查找，使用 QHostInfo::fromName () 函数：

QHostInfo info = QHostInfo::fromName("qt-project.org");

QHostInfo supports Internationalized Domain Names (IDNs) through the IDNA and Punycode standards.

To retrieve the name of the local host, use the static QHostInfo::localHostName () 函数。

QHostInfo uses the mechanisms provided by the operating system to perform the lookup. As per {https://tools.ietf.org/html/rfc6724}{RFC 6724} there is no guarantee that all IP addresses registered for a domain or host will be returned.

注意： Since Qt 4.6.1 QHostInfo is using multiple threads for DNS lookup instead of one dedicated DNS thread. This improves performance, but also changes the order of signal emissions when using lookupHost () compared to previous versions of Qt.

注意： Since Qt 4.6.3 QHostInfo is using a small internal 60 second DNS cache for performance improvements.

另请参阅 QAbstractSocket , RFC 3492 ，和 RFC 6724 .

成员类型文档编制

enum QHostInfo:: HostInfoError

This enum describes the various errors that can occur when trying to resolve a host name.

常量	值	描述
`QHostInfo::NoError`	`0`	查找成功。
`QHostInfo::HostNotFound`	`1`	No IP addresses were found for the host.
`QHostInfo::UnknownError`	`2`	出现未知错误。

另请参阅 error () 和 setError ().

成员函数文档编制

QHostInfo:: QHostInfo ( QHostInfo && other )

Move-constructs a new QHostInfo from other .

注意： The moved-from object other is placed in a partially-formed state, in which the only valid operations are destruction and assignment of a new value.

该函数在 Qt 5.14 引入。

QHostInfo:: QHostInfo (const QHostInfo & other )

构造副本为 other .

QHostInfo:: QHostInfo ( int id = -1)

Constructs an empty host info object with lookup ID id .

另请参阅 lookupId ().

QHostInfo &QHostInfo:: operator= ( QHostInfo && other )

移动赋值 other 到此 QHostInfo 实例。

注意： The moved-from object other is placed in a partially-formed state, in which the only valid operations are destruction and assignment of a new value.

该函数在 Qt 5.10 引入。

QHostInfo &QHostInfo:: operator= (const QHostInfo & other )

赋值数据源于 other object to this host info object, and returns a reference to it.

QHostInfo:: ~QHostInfo ()

Destroys the host info object.

`[static]` void QHostInfo:: abortHostLookup ( int id )

Aborts the host lookup with the ID id , as returned by lookupHost ().

另请参阅 lookupHost () 和 lookupId ().

QList < QHostAddress > QHostInfo:: addresses () const

Returns the list of IP addresses associated with hostName (). This list may be empty.

范例：

QHostInfo info;
...
if (!info.addresses().isEmpty()) {
    QHostAddress address = info.addresses().first();
    // use the first IP address
}

另请参阅 setAddresses (), hostName ()，和 error ().

QHostInfo::HostInfoError QHostInfo:: error () const

Returns the type of error that occurred if the host name lookup failed; otherwise returns NoError .

另请参阅 setError () 和 errorString ().

QString QHostInfo:: errorString () const

If the lookup failed, this function returns a human readable description of the error; otherwise "Unknown error" is returned.

另请参阅 setErrorString () 和 error ().

`[static]` QHostInfo QHostInfo:: fromName (const QString & name )

Looks up the IP address(es) for the given host name . The function blocks during the lookup which means that execution of the program is suspended until the results of the lookup are ready. Returns the result of the lookup in a QHostInfo 对象。

If you pass a literal IP address to name instead of a host name, QHostInfo will search for the domain name for the IP (i.e., QHostInfo will perform a reverse lookup). On success, the returned QHostInfo will contain both the resolved domain name and IP addresses for the host name.

另请参阅 lookupHost ().

QString QHostInfo:: hostName () const

Returns the name of the host whose IP addresses were looked up.

另请参阅 setHostName () 和 localHostName ().

`[static]` QString QHostInfo:: localDomainName ()

Returns the DNS domain of this machine.

注意： DNS domains are not related to domain names found in Windows networks.

另请参阅 hostName ().

`[static]` QString QHostInfo:: localHostName ()

Returns this machine's host name, if one is configured. Note that hostnames are not guaranteed to be globally unique, especially if they were configured automatically.

This function does not guarantee the returned host name is a Fully Qualified Domain Name (FQDN). For that, use fromName () to resolve the returned name to an FQDN.

此函数返回如同 QSysInfo::machineHostName ().

另请参阅 hostName () 和 localDomainName ().

`[static]` int QHostInfo:: lookupHost (const QString & name , QObject * receiver , const char * member )

Looks up the IP address(es) associated with host name name , and returns an ID for the lookup. When the result of the lookup is ready, the slot or signal member in receiver is called with a QHostInfo 自变量。 QHostInfo object can then be inspected to get the results of the lookup.

The lookup is performed by a single function call, for example:

QHostInfo::lookupHost("www.kde.org",
                      this, SLOT(lookedUp(QHostInfo)));

The implementation of the slot prints basic information about the addresses returned by the lookup, or reports an error if it failed:

void MyWidget::lookedUp(const QHostInfo &host)
{
    if (host.error() != QHostInfo::NoError) {
        qDebug() << "Lookup failed:" << host.errorString();
        return;
    }
    const auto addresses = host.addresses();
    for (const QHostAddress &address : addresses)
        qDebug() << "Found address:" << address.toString();
}

If you pass a literal IP address to name instead of a host name, QHostInfo will search for the domain name for the IP (i.e., QHostInfo will perform a reverse lookup). On success, the resulting QHostInfo will contain both the resolved domain name and IP addresses for the host name. Example:

QHostInfo::lookupHost("4.2.2.1",
                      this, SLOT(lookedUp(QHostInfo)));

注意： There is no guarantee on the order the signals will be emitted if you start multiple requests with lookupHost().

另请参阅 abortHostLookup (), addresses (), error ()，和 fromName ().

`[static]` template <typename Functor> int QHostInfo:: lookupHost (const QString & name , Functor functor )

这是重载函数。

Looks up the IP address(es) associated with host name name , and returns an ID for the lookup. When the result of the lookup is ready, the functor is called with a QHostInfo 自变量。 QHostInfo object can then be inspected to get the results of the lookup.

The functor will be run in the thread that makes the call to lookupHost; that thread must have a running Qt event loop.

注意： There is no guarantee on the order the signals will be emitted if you start multiple requests with lookupHost().

该函数在 Qt 5.9 引入。

另请参阅 abortHostLookup (), addresses (), error ()，和 fromName ().

`[static]` template <typename Functor> int QHostInfo:: lookupHost (const QString & name , const QObject * context , Functor functor )

这是重载函数。

若 context is destroyed before the lookup completes, the functor will not be called. The functor will be run in the thread of context 。上下文线程必须拥有正在运行的 Qt 事件循环。

Here is an alternative signature for the function:

lookupHost(const QString &name, const QObject *receiver, PointerToMemberFunction function)

In this case, when the result of the lookup is ready, the slot or signal function in receiver is called with a QHostInfo 自变量。 QHostInfo object can then be inspected to get the results of the lookup.

注意： There is no guarantee on the order the signals will be emitted if you start multiple requests with lookupHost().

该函数在 Qt 5.9 引入。

另请参阅 abortHostLookup (), addresses (), error ()，和 fromName ().

int QHostInfo:: lookupId () const

Returns the ID of this lookup.

另请参阅 setLookupId (), abortHostLookup ()，和 hostName ().

void QHostInfo:: setAddresses (const QList < QHostAddress > & addresses )

Sets the list of addresses in this QHostInfo to addresses .

另请参阅 addresses ().

void QHostInfo:: setError ( QHostInfo::HostInfoError error )

Sets the error type of this QHostInfo to error .

另请参阅 error () 和 errorString ().

void QHostInfo:: setErrorString (const QString & str )

Sets the human readable description of the error that occurred to str if the lookup failed.

另请参阅 errorString () 和 setError ().

void QHostInfo:: setHostName (const QString & hostName )

Sets the host name of this QHostInfo to hostName .

另请参阅 hostName ().

void QHostInfo:: setLookupId ( int id )

Sets the ID of this lookup to id .

另请参阅 lookupId () 和 lookupHost ().

void QHostInfo:: swap ( QHostInfo & other )

Swaps host-info other with this host-info. This operation is very fast and never fails.

该函数在 Qt 5.10 引入。

QHostInfo 类

公共类型

公共函数

静态公共成员

详细描述

成员类型文档编制

enum QHostInfo:: HostInfoError

成员函数文档编制

QHostInfo:: QHostInfo ( QHostInfo && other )

QHostInfo:: QHostInfo (const QHostInfo & other )

QHostInfo:: QHostInfo ( int id = -1)

QHostInfo &QHostInfo:: operator= ( QHostInfo && other )

QHostInfo &QHostInfo:: operator= (const QHostInfo & other )

QHostInfo:: ~QHostInfo ()

[static] void QHostInfo:: abortHostLookup ( int id )

QList < QHostAddress > QHostInfo:: addresses () const

QHostInfo::HostInfoError QHostInfo:: error () const

QString QHostInfo:: errorString () const

[static] QHostInfo QHostInfo:: fromName (const QString & name )

QString QHostInfo:: hostName () const

[static] QString QHostInfo:: localDomainName ()

[static] QString QHostInfo:: localHostName ()

[static] int QHostInfo:: lookupHost (const QString & name , QObject * receiver , const char * member )

[static] template <typename Functor> int QHostInfo:: lookupHost (const QString & name , Functor functor )

[static] template <typename Functor> int QHostInfo:: lookupHost (const QString & name , const QObject * context , Functor functor )

int QHostInfo:: lookupId () const

void QHostInfo:: setAddresses (const QList < QHostAddress > & addresses )

void QHostInfo:: setError ( QHostInfo::HostInfoError error )

void QHostInfo:: setErrorString (const QString & str )

void QHostInfo:: setHostName (const QString & hostName )

void QHostInfo:: setLookupId ( int id )

void QHostInfo:: swap ( QHostInfo & other )

内容

`[static]` void QHostInfo:: abortHostLookup ( int id )

`[static]` QHostInfo QHostInfo:: fromName (const QString & name )

`[static]` QString QHostInfo:: localDomainName ()

`[static]` QString QHostInfo:: localHostName ()

`[static]` int QHostInfo:: lookupHost (const QString & name , QObject * receiver , const char * member )

`[static]` template <typename Functor> int QHostInfo:: lookupHost (const QString & name , Functor functor )

`[static]` template <typename Functor> int QHostInfo:: lookupHost (const QString & name , const QObject * context , Functor functor )