应用扩展允许应用托管来自其他包的外接程序内容和功能。 这是插件模型的Windows等效项。 扩展提供程序声明内容或服务，主机应用会在运行时发现并加载它们。
Important
应用扩展需要主机和扩展应用的 MSIX 包标识 。 扩展是通过包目录发现的。
应用扩展的工作原理
应用扩展模型具有两个角色：
- 扩展主机 - 你的应用声明它接受的扩展类型并发现已安装的扩展。
- 扩展提供程序 - 另一个应用（或同一应用）声明它提供特定类型的扩展。
扩展通过包清单声明而不是代码进行通信。 主机应用使用 AppExtensionCatalog API 查找和管理已安装的扩展。
声明扩展主机
将 AppExtensionHost 声明添加到应用的 Package.appxmanifest：
<Package xmlns:uap3="http://schemas.microsoft.com/appx/manifest/uap/windows10/3" ...>
<Applications>
<Application ...>
<Extensions>
<uap3:Extension Category="windows.appExtensionHost">
<uap3:AppExtensionHost>
<uap3:Name>com.example.myapp.extensions</uap3:Name>
</uap3:AppExtensionHost>
</uap3:Extension>
</Extensions>
</Application>
</Applications>
</Package>
声明扩展提供程序
在扩展应用的 Package.appxmanifest 中：
<Package xmlns:uap3="http://schemas.microsoft.com/appx/manifest/uap/windows10/3" ...>
<Applications>
<Application ...>
<Extensions>
<uap3:Extension Category="windows.appExtension">
<uap3:AppExtension Name="com.example.myapp.extensions"
Id="MathExtension"
DisplayName="Math Functions"
Description="Provides math operations"
PublicFolder="Public">
</uap3:AppExtension>
</uap3:Extension>
</Extensions>
</Application>
</Applications>
</Package>
PublicFolder 指向扩展包中宿主应用可以读取的文件夹。
查找并加载扩展程序
在宿主应用中，使用 AppExtensionCatalog 来发现已安装的扩展：
private AppExtensionCatalog? _catalog;
private async Task InitializeExtensionsAsync()
{
_catalog = AppExtensionCatalog.Open("com.example.myapp.extensions");
_catalog.PackageInstalled += OnExtensionInstalled;
_catalog.PackageUpdated += OnExtensionUpdated;
_catalog.PackageUninstalling += OnExtensionRemoved;
var extensions = await _catalog.FindAllAsync();
foreach (var extension in extensions)
{
await LoadExtensionAsync(extension);
}
}
private async Task LoadExtensionAsync(AppExtension extension)
{
string extensionId = extension.Id;
string displayName = extension.DisplayName;
// Get the extension's public folder
var folder = await extension.GetPublicFolderAsync();
if (folder != null)
{
// Read configuration, content, or scripts from the folder
var configFile = await folder.TryGetItemAsync("config.json");
if (configFile != null)
{
// Parse and use the extension configuration
}
}
}
// See "Handle extension lifecycle events" below for the
// OnExtensionInstalled, OnExtensionUpdated, and OnExtensionRemoved handlers.
private async void OnExtensionInstalled(AppExtensionCatalog sender,
AppExtensionPackageInstalledEventArgs args) { }
private async void OnExtensionUpdated(AppExtensionCatalog sender,
AppExtensionPackageUpdatedEventArgs args) { }
private void OnExtensionRemoved(AppExtensionCatalog sender,
AppExtensionPackageUninstallingEventArgs args) { }
处理扩展生命周期事件
private async Task LoadExtensionAsync(AppExtension extension) => await Task.CompletedTask;
// (See "Discover and load extensions" above for the real implementation.)
private async void OnExtensionInstalled(AppExtensionCatalog sender,
AppExtensionPackageInstalledEventArgs args)
{
// Re-query the catalog to get the AppExtension instances added by this package
var extensions = await sender.FindAllAsync();
foreach (var extension in extensions.Where(e => e.Package.Id.FamilyName == args.Package.Id.FamilyName))
{
await LoadExtensionAsync(extension);
}
}
private void OnExtensionRemoved(AppExtensionCatalog sender,
AppExtensionPackageUninstallingEventArgs args)
{
// args.Package identifies the package that is uninstalling
string familyName = args.Package.Id.FamilyName;
// Remove any extensions from that package from your app
}
private async void OnExtensionUpdated(AppExtensionCatalog sender,
AppExtensionPackageUpdatedEventArgs args)
{
// Re-query the catalog to get the refreshed AppExtension instances
var extensions = await sender.FindAllAsync();
foreach (var extension in extensions.Where(e => e.Package.Id.FamilyName == args.Package.Id.FamilyName))
{
// Reload with updated content
await LoadExtensionAsync(extension);
}
}
