static void TestWeakRef()
{
_ref =
ExtendedWeakReference.RecoverOrCreate(
typeof(TypeUniqueToOurApp), //作为标识的类
0, //ID标识，这个比较有用
ExtendedWeakReference.c_SurvivePowerdown);
//数据重要次序：OkayToThrowAway->NiceToHave->Important->Critical->System
_ref.Priority = (Int32)ExtendedWeakReference.PriorityLevel.Important;
//获取数据
var numBoots = (NumBoots)_ref.Target;
if (numBoots == null)
{
Debug.Print("the first time!");
numBoots = new NumBoots(1);
}
else
{
numBoots = new NumBoots(numBoots.BootCount + 1);
Debug.Print("This is boot #" + numBoots.BootCount);
}
//保存数据
_ref.Target = numBoots;
//延时等待保存
Thread.Sleep(2000);
}
/// <summary>
/// The execution entry point.
/// </summary>
public static void Main()
{
// We are booting; try to retrieve the boot count.
s_numBootsExtendedWeakReference =
ExtendedWeakReference.RecoverOrCreate(
typeof(TypeUniqueToOurApp), // The unique type that identifies the data.
0, // The ID of the specific data item.
ExtendedWeakReference.c_SurvivePowerdown); // The CLR should try to persist data across a reboot.
// Indicate how important this data is. The CLR discards
// OkayToThrowAway items first, then NiceToHave items, then
// Important items, then Critical items, and finally System items.
// In practice, System items are virtually never discarded.
s_numBootsExtendedWeakReference.Priority =
(Int32)ExtendedWeakReference.PriorityLevel.Important;
// Try to get the persisted data, initializing it if it is not
// available. The Target property of the extended weak reference
// must be cast to the actual type of the object. The Target
// property is cast to prevent the object from being
// garbage-collected unexpectedly.
NumBoots numBoots = (NumBoots)s_numBootsExtendedWeakReference.Target;
if (numBoots == null)
{
// The object could not be found in flash memory, so create the
// object and initialize it.
Debug.Print(
"The device was booted for the first time, or the boot counter was lost. Initializing the boot counter to 1.");
numBoots = new NumBoots(1);
}
else
{
// The object was found in flash memory; increment the boot
// counter.
numBoots = new NumBoots(numBoots.BootCount + 1);
Debug.Print("Successfully read boot counter. This is boot #" +
numBoots.BootCount);
}
// Set the Target property of the extended weak reference to the
// boot count object, triggering persistence.
s_numBootsExtendedWeakReference.Target = numBoots;
// The CLR needs some time to asynchronously store the data in
// flash. In this sample application, we use a two-second Sleep.
// A real application would simply continue without delay. This app
// only needs to sleep because the application is about to end.
// The system provides no guarantee about when the data will
// actually be stored in flash memory. When the data is actually
// stored depends on the size of the object and the speed of the
// flash memory.
System.Threading.Thread.Sleep(2000);
}
/// <summary>
/// The execution entry point.
/// </summary>
public static void Run()
{
// We are booting; try to retrieve the boot count.
s_numBootsExtendedWeakReference =
ExtendedWeakReference.RecoverOrCreate(
typeof(TypeUniqueToOurApp), // The unique type that identifies the data.
0, // The ID of the specific data item.
ExtendedWeakReference.c_SurviveBoot); // The CLR should try to persist data across a reboot.
// Indicate how important this data is. The CLR discards
// OkayToThrowAway items first, then NiceToHave items, then
// Important items, then Critical items, and finally System items.
// In practice, System items are virtually never discarded.
s_numBootsExtendedWeakReference.Priority =
(Int32)ExtendedWeakReference.PriorityLevel.Important;
// Try to get the persisted data, initializing it if it is not
// available. The Target property of the extended weak reference
// must be cast to the actual type of the object. The Target
// property is cast to prevent the object from being
// garbage-collected unexpectedly.
NumBoots numBoots = (NumBoots)s_numBootsExtendedWeakReference.Target;
if (numBoots == null)
{
// The object could not be found in flash memory, so create the
// object and initialize it.
Debug.Print(
"The device was booted for the first time, or the boot counter was lost. Initializing the boot counter to 1.");
numBoots = new NumBoots(1);
}
else
{
// The object was found in flash memory; increment the boot
// counter.
numBoots = new NumBoots(numBoots.BootCount + 1);
Debug.Print("Successfully read boot counter. This is boot #" +
numBoots.BootCount);
}
// Set the Target property of the extended weak reference to the
// boot count object, triggering persistence.
s_numBootsExtendedWeakReference.Target = numBoots;
// The CLR needs some time to asynchronously store the data in
// flash. In this sample application, we use a two-second Sleep.
// A real application would simply continue without delay. This app
// only needs to sleep because the application is about to end.
// The system provides no guarantee about when the data will
// actually be stored in flash memory. When the data is actually
// stored depends on the size of the object and the speed of the
// flash memory.
// System.Threading.Thread.Sleep(2000);
}
