一、基本思路：
首先程序运行时注册按键事件，然后将程序转入后台运行，当按键事件发生后在AppUi的HandleKeyEventL中处理。
相关代码如下：
void CClockSSAppUi::SetCaptureKey()
{
// If there is another handle, we have to cancel it first.
CancelCaptureKey();
// This will capture scan code of the keypress.
iHandleCaptureKey = CCoeEnv::Static()-> RootWin().CaptureKeyUpAndDowns(
KOkKeyScanCode, EModifierShift, EModifierShift PRIORITYCAPTUREKEY);
//// WARNING: We need to capture the normal code of keypress otherwise
// the key event will be sent to another application.
iHandleCaptureKey2 = CCoeEnv::Static()-> RootWin().CaptureKey(
KOkKeyCode, EModifierShift, EModifierShift PRIORITYCAPTUREKEY);
}
TKeyResponse CClockSSAppUi::HandleKeyEventL(const TKeyEvent& aKeyEvent,TEventCode aType)
{
if ((KOkKeyScanCode == (TUint) aKeyEvent.iScanCode) && (EEventKeyDown == aType)
&& ((aKeyEvent.iModifiers & EModifierShift) == EModifierShift) )
{
CAknGlobalNote* globalNote = CAknGlobalNote::NewLC();
globalNote->ShowNoteL(EAknGlobalInformationNote, _L(”Captured KEY!”));
CleanupStack::PopAndDestroy();
}
}
需要注意的是：如果你的是多view程序，并且调用了AppUi::AddToStackL接收按键事件，那么在这些控件OfferKeyEventL的处理中对于不相关的键事件一定要返回EKeyWasNotConsumed,好让AppUi最后能处理。
二、如何将程序送到后台运行
比如说，当按下back后，在HandleCommandL()中加入如下处理：
case EAknSoftkeyBack:
{
TApaTask apaTask(iEikonEnv->WsSession());
apaTask.SetWgId(CCoeEnv::Static()->RootWin().Identifier());
apaTask.SendToBackground();
break;
}
解释一下：
A task is a running application.
A task is identified by its association with the running application’s window group.
apaTask把自己送到后台，并在后台继续运行。
首先程序运行时注册按键事件，然后将程序转入后台运行，当按键事件发生后在AppUi的HandleKeyEventL中处理。
相关代码如下：
void CClockSSAppUi::SetCaptureKey()
{
// If there is another handle, we have to cancel it first.
CancelCaptureKey();
// This will capture scan code of the keypress.
iHandleCaptureKey = CCoeEnv::Static()-> RootWin().CaptureKeyUpAndDowns(
KOkKeyScanCode, EModifierShift, EModifierShift PRIORITYCAPTUREKEY);
//// WARNING: We need to capture the normal code of keypress otherwise
// the key event will be sent to another application.
iHandleCaptureKey2 = CCoeEnv::Static()-> RootWin().CaptureKey(
KOkKeyCode, EModifierShift, EModifierShift PRIORITYCAPTUREKEY);
}
TKeyResponse CClockSSAppUi::HandleKeyEventL(const TKeyEvent& aKeyEvent,TEventCode aType)
{
if ((KOkKeyScanCode == (TUint) aKeyEvent.iScanCode) && (EEventKeyDown == aType)
&& ((aKeyEvent.iModifiers & EModifierShift) == EModifierShift) )
{
CAknGlobalNote* globalNote = CAknGlobalNote::NewLC();
globalNote->ShowNoteL(EAknGlobalInformationNote, _L(”Captured KEY!”));
CleanupStack::PopAndDestroy();
}
}
需要注意的是：如果你的是多view程序，并且调用了AppUi::AddToStackL接收按键事件，那么在这些控件OfferKeyEventL的处理中对于不相关的键事件一定要返回EKeyWasNotConsumed,好让AppUi最后能处理。
二、如何将程序送到后台运行
比如说，当按下back后，在HandleCommandL()中加入如下处理：
case EAknSoftkeyBack:
{
TApaTask apaTask(iEikonEnv->WsSession());
apaTask.SetWgId(CCoeEnv::Static()->RootWin().Identifier());
apaTask.SendToBackground();
break;
}
解释一下：
A task is a running application.
A task is identified by its association with the running application’s window group.
apaTask把自己送到后台，并在后台继续运行。
