QDesktopServices 类

QDesktopServices 类提供用于访问常见桌面服务的方法。更多...

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

该类在 Qt 4.2 引入。

静态公共成员

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

详细描述

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.

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 类。

另请参阅 QSystemTrayIcon , QProcess ，和 QStandardPaths .

成员函数文档编制

`[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；否则返回 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:/Program Files", 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.

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 方案启用 URL：

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

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。

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

要使用该函数从 iOS 其它 APP 接收数据，还需要把自定义方案添加到 CFBundleURLSchemes 列表，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，见 Apple 开发者文档编制使用自定义 URL 与其它 APP 进行通信 .

警告： It is not possible to claim support for some well known URL schemes, including http and https. This is only allowed for Universal Links.

To claim support for http and https the above entry in the Info.plist file is not allowed. This is only possible when you add your domain to the Entitlements file:

<key>com.apple.developer.associated-domains</key>
<array>
    <string>applinks:your.domain.com</string>
</array>

iOS will search for /.well-known/apple-app-site-association on your domain, when the application is installed. If you want to listen to https://your.domain.com/help?topic=ABCDEF you need to provide the following content there:

{
    "applinks": {
        "apps": [],
        "details": [{
            "appIDs" : [ "ABCDE12345.com.example.app" ],
            "components": [{
                "/": "/help",
                "?": { "topic": "?*"}
            }]
        }]
    }
}

更多信息，见 Apple 开发者文档编制 https://developer.apple.com/documentation/safariservices/supporting_associated_domains_in_your_app [Supporting Associated Domains}.

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 ().

必须调用 unsetUrlHandler () before destroying the handler object, so the destruction of the handler object does not overlap with concurrent invocations of openUrl () using it.

另请参阅 openUrl () 和 unsetUrlHandler ().

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

移除先前设置的 URL 处理程序，为指定的 scheme .

Call this function before the handler object that was registered for scheme is destroyed, to prevent concurrent openUrl () calls from continuing to call the destroyed handler object.