内容

公共类型
静态公共成员
详细描述
URL 处理程序

QDesktopServices 类

The QDesktopServices class provides methods for accessing common desktop services. 更多...

头：	#include <QDesktopServices>
Since:	Qt 4.2

所有成员列表，包括继承成员

公共类型

enum	StandardLocation { DesktopLocation, DocumentsLocation, FontsLocation, ApplicationsLocation, ..., CacheLocation }

静态公共成员

QString	displayName (StandardLocation type )
bool	openUrl (const QUrl & url )
void	setUrlHandler (const QString & scheme , QObject * receiver , const char * method )
QString	storageLocation (StandardLocation type )
void	unsetUrlHandler (const QString & scheme )

详细描述

The QDesktopServices class provides methods for accessing common desktop services.

许多桌面环境提供可用于应用程序以履行常见任务的服务 (譬如：打开网页)，按一致且考虑到用户应用程序首选的方式。

This class contains functions that provide simple interfaces to these services that indicate whether they succeeded or failed.

The openUrl () function is used to open files located at arbitrary URLs in external applications. For URLs that correspond to resources on the local filing system (where the URL scheme is "file"), a suitable application will be used to open the file; otherwise, a web browser will be used to fetch and display the file.

The user's desktop settings control whether certain executable file types are opened for browsing, or if they are executed instead. Some desktop environments are configured to prevent users from executing files obtained from non-local URLs, or to ask the user's permission before doing so.

URL 处理程序

The behavior of the openUrl () function can be customized for individual URL schemes to allow applications to override the default handling behavior for certain types of URLs.

The dispatch mechanism allows only one custom handler to be used for each URL scheme; this is set using the setUrlHandler () function. Each handler is implemented as a slot which accepts only a single QUrl 自变量。

The existing handlers for each scheme can be removed with the unsetUrlHandler () function. This returns the handling behavior for the given scheme to the default behavior.

This system makes it easy to implement a help system, for example. Help could be provided in labels and text browsers using help://myapplication/mytopic URLs, and by registering a handler it becomes possible to display the help text inside the application:

class MyHelpHandler : public QObject
{
    Q_OBJECT
public:
    ...
public slots:
    void showHelp(const QUrl &url);
};
QDesktopServices::setUrlHandler("help", helpInstance, "showHelp");

If inside the handler you decide that you can't open the requested URL, you can just call QDesktopServices::openUrl () again with the same argument, and it will try to open the URL using the appropriate mechanism for the user's desktop environment.

另请参阅 QSystemTrayIcon and QProcess .

成员类型文档编制

enum QDesktopServices:: StandardLocation

This enum describes the different locations that can be queried by QDesktopServices::storageLocation and QDesktopServices::displayName .

常量	值	描述
`QDesktopServices::DesktopLocation`	`0`	Returns the user's desktop directory.
`QDesktopServices::DocumentsLocation`	`1`	Returns the user's document.
`QDesktopServices::FontsLocation`	`2`	Returns the user's fonts.
`QDesktopServices::ApplicationsLocation`	`3`	Returns the user's applications.
`QDesktopServices::MusicLocation`	`4`	Returns the users music.
`QDesktopServices::MoviesLocation`	`5`	Returns the user's movies.
`QDesktopServices::PicturesLocation`	`6`	Returns the user's pictures.
`QDesktopServices::TempLocation`	`7`	Returns the system's temporary directory.
`QDesktopServices::HomeLocation`	`8`	Returns the user's home directory.
`QDesktopServices::DataLocation`	`9`	Returns a directory location where persistent application data can be stored. QCoreApplication::applicationName and QCoreApplication::organizationName should work on all platforms.
`QDesktopServices::CacheLocation`	`10`	Returns a directory location where user-specific non-essential (cached) data should be written.

该枚举在 Qt 4.4 引入或被修改。

另请参阅 storageLocation () 和 displayName ().

成员函数文档编制

`[static]` QString QDesktopServices:: displayName ( StandardLocation type )

Returns a localized display name for the given location type or an empty QString if no relevant location can be found.

`[static]` bool QDesktopServices:: openUrl (const QUrl & url )

Opens the given url in the appropriate Web browser for the user's desktop environment, and returns true if successful; otherwise returns false.

If the URL is a reference to a local file (i.e., the URL scheme is "file") then it will be opened with a suitable application instead of a Web browser.

The following example opens a file on the Windows file system residing on a path that contains spaces:

QDesktopServices::openUrl(QUrl("file:///C:/Documents and Settings/All Users/Desktop", QUrl::TolerantMode));

若 mailto URL is specified, the user's e-mail client will be used to open a composer window containing the options specified in the URL, similar to the way mailto links are handled by a Web browser.

For example, the following URL contains a recipient ( user@foo.com ), a subject ( 测试 ), and a message body ( Just a test ):

mailto:user@foo.com?subject=Test&body=Just a test

警告： Although many e-mail clients can send attachments and are Unicode-aware, the user may have configured their client without these features. Also, certain e-mail clients (e.g., Lotus Notes) have problems with long URLs.

注意： On Symbian OS, SwEvent capability is required to open the given url if the Web browser is already running.

另请参阅 setUrlHandler ().

`[static]` void QDesktopServices:: setUrlHandler (const QString & scheme , QObject * receiver , const char * method )

设置处理程序为给定 scheme to be the handler method provided by the receiver 对象。

This function provides a way to customize the behavior of openUrl ()。若 openUrl () is called with a URL with the specified scheme then the given method 在 receiver object is called instead of QDesktopServices 发起外部应用程序。

提供方法必须被实现成槽，且其只接受单 QUrl 自变量。

If setUrlHandler() is used to set a new handler for a scheme which already has a handler, the existing handler is simply replaced with the new one. Since QDesktopServices 不拥有处理程序的所有权，因此，当替换处理程序时没有对象会被删除。

注意：总是在其内调用处理程序的线程，也会调用 QDesktopServices::openUrl ().

另请参阅 openUrl () 和 unsetUrlHandler ().

`[static]` QString QDesktopServices:: storageLocation ( StandardLocation type )

Returns the default system directory where files of type belong, or an empty string if the location cannot be determined.

注意： The storage location returned can be a directory that does not exist; i.e., it may need to be created by the system or the user.

注意： On Symbian OS, ApplicationsLocation always point /sys/bin folder on the same drive with executable. FontsLocation always points to folder on ROM drive. Symbian OS does not have desktop concept, DesktopLocation returns same path as DocumentsLocation . Rest of the standard locations point to folder on same drive with executable, except that if executable is in ROM the folder from C drive is returned.

该函数在 Qt 4.4 引入。

`[static]` void QDesktopServices:: unsetUrlHandler (const QString & scheme )

移除先前设置的 URL 处理程序，为指定的 scheme .