QHostInfo class provides static functions for host name lookups. 更多...
| 头： | #include <QHostInfo> |
| qmake: | QT += network |
注意： 此类的所有函数 可重入 .
| enum | HostInfoError { NoError, HostNotFound, UnknownError } |
| QHostInfo (int id = -1) | |
| QHostInfo (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 ) |
| QHostInfo & | operator= (const QHostInfo & other ) |
| QHostInfo & | operator= (QHostInfo && other ) |
| 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 , const QObject * receiver , PointerToMemberFunction function ) |
| int | lookupHost (const QString & name , Functor functor ) |
| int | lookupHost (const QString & name , const QObject * context , Functor functor ) |
QHostInfo class provides static functions for host name lookups.
QHostInfo finds the IP address(es) associated with a host name, or the host name associated with an IP address. The class provides two static convenience functions: one that works asynchronously and emits a signal once the host is found, and one that blocks and returns a 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： 从 Qt 4.6.3 起， QHostInfo is using a small internal 60 second DNS cache for performance improvements.
另请参阅 QAbstractSocket , RFC 3492 ，和 RFC 6724 .
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。 |
Constructs an empty host info object with lookup ID id .
另请参阅 lookupId ().
构造副本为 other .
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 ().
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 ().
Returns the type of error that occurred if the host name lookup failed; otherwise returns NoError .
另请参阅 setError () 和 errorString ().
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 ().
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.
This function returns the same as 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]
int
QHostInfo::
lookupHost
(const
QString
&
name
, const
QObject
*
receiver
,
PointerToMemberFunction
function
)
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 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 ().
[static]
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.
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]
int
QHostInfo::
lookupHost
(const
QString
&
name
, const
QObject
*
context
,
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.
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。
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 ().
Returns the ID of this lookup.
另请参阅 setLookupId (), abortHostLookup ()，和 hostName ().
Sets the list of addresses in this QHostInfo to addresses .
另请参阅 addresses ().
Sets the error type of this QHostInfo to error .
另请参阅 error () 和 errorString ().
Sets the human readable description of the error that occurred to str if the lookup failed.
另请参阅 errorString () 和 setError ().
Sets the host name of this QHostInfo to hostName .
另请参阅 hostName ().
Sets the ID of this lookup to id .
另请参阅 lookupId () 和 lookupHost ().
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。
赋值数据源于 other object to this host info object, and returns a reference to it.
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。