內容

靜態公共成員
詳細描述
URL 處理程序

QDesktopServices 類

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

頭：	#include <QDesktopServices>
qmake:	QT += gui
Since:	Qt 4.2

靜態公共成員

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

詳細描述

The QDesktopServices class provides methods for accessing common desktop services.

許多桌麵環境提供可用於應用程序以履行常見任務的服務 (譬如：打開網頁)，按一緻且考慮到用戶應用程序首選的方式。

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 處理程序

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 自變量。

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.

Combined with platform specific settings, the schemes registered by the openUrl () function can also be exposed to other applications, opening up for application deep linking or a very basic URL-based IPC mechanism.

注意： Since Qt 5, storageLocation() and displayName() are replaced by functionality provided by the QStandardPaths 類。

另請參閱 QSystemTrayIcon , QProcess ，和 QStandardPaths .

成員函數文檔編製

`[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 若成功；否則返迴 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 ( 測試 ), 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.

警告： A return value of true indicates that the application has successfully requested the operating system to open the URL in an external application. The external application may still fail to launch or fail to open the requested URL. This result will not be reported back to the application.

警告： URLs passed to this function on iOS will not load unless their schemes are listed in the LSApplicationQueriesSchemes key of the application's Info.plist file. For more information, see the Apple Developer Documentation for canOpenURL(_:) 。例如，以下行采用 HTTPS 方案啓用 URL：

<key>LSApplicationQueriesSchemes</key>
<array>
    <string>https</string>
</array>

另請參閱 setUrlHandler ().

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

設置處理程序為給定 scheme to be the handler method provided by the receiver 對象。

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 發起外部應用程序。

提供方法必須被實現成槽，且其隻接受單 QUrl 自變量。

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

要使用該函數從 iOS 其它 APP 接收數據，還需要把自定義方案添加到 CFBundleURLSchemes 列錶，在 Info.plist 文件中：

<key>CFBundleURLTypes</key>
<array>
    <dict>
        <key>CFBundleURLSchemes</key>
        <array>
            <string>myapp</string>
        </array>
    </dict>
</array>

更多信息，見 Apple 開發者文檔編製使用自定義 URL 與其它 APP 進行通信 .

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 不擁有處理程序的所有權，因此，當替換處理程序時沒有對象會被刪除。

注意：總是在其內調用處理程序的綫程，也會調用 QDesktopServices::openUrl ().

另請參閱 openUrl () 和 unsetUrlHandler ().

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

移除先前設置的 URL 處理程序，為指定的 scheme .