StorageLibraryChangeTracker.Enable 方法

定義

命名空間:

Windows.Storage

多載

Enable()	啟用儲存體程式庫的變更追蹤。
Enable(StorageLibraryChangeTrackerOptions)	根據變更識別碼，針對所有或最新的變更啟用儲存體程式庫的變更追蹤。

Enable()

啟用儲存體程式庫的變更追蹤。

public:
 virtual void Enable() = Enable;

void Enable();

public void Enable();

function enable()

Public Sub Enable ()

Enable(StorageLibraryChangeTrackerOptions)

根據變更識別碼，針對所有或最新的變更啟用儲存體程式庫的變更追蹤。

public:
 virtual void Enable(StorageLibraryChangeTrackerOptions ^ options) = Enable;

/// [Windows.Foundation.Metadata.Overload("EnableWithOptions")]
void Enable(StorageLibraryChangeTrackerOptions const& options);

[Windows.Foundation.Metadata.Overload("EnableWithOptions")]
public void Enable(StorageLibraryChangeTrackerOptions options);

function enable(options)

Public Sub Enable (options As StorageLibraryChangeTrackerOptions)

參數

options

StorageLibraryChangeTrackerOptions

StorageLibraryChangeTrackerOptions實例。

屬性

OverloadAttribute

Windows 需求

裝置系列	Windows 10, version 2104 (已於 10.0.20348.0 引進)
API contract	Windows.Foundation.UniversalApiContract (已於 v12.0 引進)

範例

// applications are expected to persist the previous value
UINT64 appsLastPersistedChangeId = StorageLibraryLastChangeId::Unknown();
StorageFolder folder = StorageFolder::GetFolderFromPathAsync(L"my folder path").get();

StorageLibraryChangeTracker tracker = folder.TryGetChangeTracker();
if (tracker != nullptr)
{
StorageLibraryChangeTrackerOptions ops;
ops.TrackChangeDetails(false);
tracker.Enable(ops);

StorageLibraryChangeReader reader = tracker.GetChangeReader();
if (reader != nullptr)
{
    UINT32 changeId = reader.GetLastChangeId();
    if ((changeId == StorageLibraryLastChangeId::Unknown())
    {
        ScanFolderSlow();
    }
    else if (changeId == 0)
    {
        // no changes in the storage folder yet, OR nothing has changed
        ProcessNormalApplicationStartup();
    }
    else if (changeId != appsLastPersistedChangeId)
    {
        // There have been new changes since we’ve last ran, process them
        appsLastPersistedChangeId = changeId;
        ScanFolderForChanges();
    }
    else
    {
        // changeId and our last persisted change id match, also normal application startup
        ProcessNormalApplicationStartup();
    }
}
}

備註

對於只對上次變更識別碼感興趣的應用程式，系統不會將所有變更記錄儲存在裝置上，並將儲存體變大。 在此情況下，ReadBatchAsync 一律會傳回 0 筆記錄。

另請參閱

• StorageLibraryChangeTrackerOptions