通过

StorageLibraryChangeTrackerTrigger 类

  • 参考

定义

命名空间:
Windows.ApplicationModel.Background
编辑

表示 StorageFolder 中触发后台任务运行的文件更改。

public ref class StorageLibraryChangeTrackerTrigger sealed : IBackgroundTrigger
/// [Windows.Foundation.Metadata.Activatable(Windows.ApplicationModel.Background.IStorageLibraryChangeTrackerTriggerFactory, 393216, "Windows.Foundation.UniversalApiContract")]
/// [Windows.Foundation.Metadata.ContractVersion(Windows.Foundation.UniversalApiContract, 393216)]
/// [Windows.Foundation.Metadata.MarshalingBehavior(Windows.Foundation.Metadata.MarshalingType.Agile)]
/// [Windows.Foundation.Metadata.Threading(Windows.Foundation.Metadata.ThreadingModel.Both)]
class StorageLibraryChangeTrackerTrigger final : IBackgroundTrigger
[Windows.Foundation.Metadata.Activatable(typeof(Windows.ApplicationModel.Background.IStorageLibraryChangeTrackerTriggerFactory), 393216, "Windows.Foundation.UniversalApiContract")]
[Windows.Foundation.Metadata.ContractVersion(typeof(Windows.Foundation.UniversalApiContract), 393216)]
[Windows.Foundation.Metadata.MarshalingBehavior(Windows.Foundation.Metadata.MarshalingType.Agile)]
[Windows.Foundation.Metadata.Threading(Windows.Foundation.Metadata.ThreadingModel.Both)]
public sealed class StorageLibraryChangeTrackerTrigger : IBackgroundTrigger
function StorageLibraryChangeTrackerTrigger(tracker)
Public NotInheritable Class StorageLibraryChangeTrackerTrigger
Implements IBackgroundTrigger
继承
Object Platform::Object IInspectable StorageLibraryChangeTrackerTrigger
属性
ActivatableAttribute ContractVersionAttribute MarshalingBehaviorAttribute ThreadingAttribute
实现
IBackgroundTrigger

Windows 要求

设备系列
Windows 10, version 1803 (在 10.0.17134.0 中引入)
API contract
Windows.Foundation.UniversalApiContract (在 v6.0 中引入)

示例

以下示例演示如何为指定文件夹创建和注册存储库更改触发器。

private async Task<bool> RegisterBackgroundTask(StorageFolder folder)
{
    StorageLibraryChangeTracker tracker = folder.TryGetChangeTracker();
    if (tracker != null)
    {
        tracker.Enable();

        StorageLibraryChangeTrackerTrigger trigger = new StorageLibraryChangeTrackerTrigger(tracker);

        string name = "StorageLibraryChangeTrackerTask"; // a friendly task name
        string taskEntryPoint = "Tasks.StorageLibraryChangeTrackerTask";

        var access = await BackgroundExecutionManager.RequestAccessAsync(); // to register background tasks, you must first call RequestAccessAsync()

        BackgroundTaskBuilder builder = new BackgroundTaskBuilder();
        builder.Name = name;
        builder.TaskEntryPoint = taskEntryPoint;
        builder.SetTrigger(trigger);
        BackgroundTaskRegistration task = builder.Register();

        return true;
    }

    // Not getting a tracker means we don't have access to the folder or it’s not a physical folder
    return false;
}

注解

在注册成功之前，必须在清单中声明后台任务。

构造函数

StorageLibraryChangeTrackerTrigger(StorageLibraryChangeTracker)

初始化新的 StorageLibraryChangeTrackerTrigger 实例。

适用于

另请参阅