Hi
Has anybody successfully hooked into the Windows shutdown messages? I've
been beating my head against this for a while, and I just can't seem to get
anything useful.
I definitely seem to be getting normal windows messages, but I never seem
to receive the critical WM_ENDSESSION message.
Thanks, Noel Grandin
public class ShutdownDetect
{
/**
* @see <a
href="http://msdn.microsoft.com/en-us/library/aa376889.aspx">WM_ENDSESSION
reference</a>
*/
public static final int WM_ENDSESSION = 0x16;
public static final int WM_QUERYENDSESSION = 0x11;
public interface IShutdownListener
{
void onShutdown();
}
public static class CWPSSTRUCT extends Structure
{
public LPARAM lParam;
public WPARAM wParam;
public DWORD message;
public HWND hwnd;
}
public interface WinHookProc extends WinUser.HOOKPROC
{
/**
* @see <a
href="
http://msdn.microsoft.com/en-us/library/windows/desktop/ms644975(v=vs...">CallWndProc
* callback function</a>
* @param nCode is an action parameter. anything less than zero indicates I
should ignore this call.
* @param wParam Specifies whether the message was sent by the current
thread. If the message was sent by the
* current thread, it is nonzero; otherwise, it is zero
* @param hookProcStruct A pointer to a CWPSTRUCT structure that contains
details about the message.
* @return If nCode is less than zero, the hook procedure must return the
value returned by CallNextHookEx.
*/
WinDef.LRESULT callback(int nCode, WinDef.WPARAM wParam, CWPSSTRUCT
hookProcStruct);
}
public static final class MyHookProc implements WinHookProc
{
public IShutdownListener listener;
public WinUser.HHOOK hhook;
@Override
public LRESULT callback(int nCode, WPARAM wParam, CWPSSTRUCT
hookProcStruct) {
if (nCode >= 0) {
System.out.println(hookProcStruct.message);
// tell the OS it's OK to shut down
if (hookProcStruct.message.longValue() == WM_QUERYENDSESSION) {
System.out.println("WM_QUERYENDSESSION");
return new LRESULT(1);
}
// process the actual shutting down message
if (hookProcStruct.message.longValue() == WM_ENDSESSION) {
System.out.println("WM_ENDSESSION");
listener.onShutdown();
return new LRESULT(0); // return success
}
}
// pass the callback on to the next hook in the chain
return User32.INSTANCE.CallNextHookEx(hhook, nCode, wParam,
hookProcStruct.getPointer());
}
}
public static void register(JFrame frame, final IShutdownListener listener)
{
Native.setCallbackExceptionHandler(new Callback.UncaughtExceptionHandler() {
@Override
public void uncaughtException(Callback arg0, Throwable arg1) {
arg1.printStackTrace();
}
});
// get the window handle for the main window/frame
final HWND hwnd = new HWND();
hwnd.setPointer(Native.getComponentPointer(frame));
// clear the error value
Native.setLastError(0);
// retrieve the threadID associated with the main window/frame
int windowThreadID = User32.INSTANCE.GetWindowThreadProcessId(hwnd, null);
if (windowThreadID == 0) {
int x = Native.getLastError();
throw new IllegalStateException(
"error calling GetWindowThreadProcessId when installing machine-shutdown
handler " + x);
}
// clear the error value
Native.setLastError(0);
final MyHookProc proc = new MyHookProc();
proc.listener = listener;
proc.hhook = User32.INSTANCE.SetWindowsHookEx(12/* WH_CALLWNDPROCRET */,
new MyHookProc(),
null, windowThreadID/* dwThreadID */);
// null indicates failure
if (proc.hhook == null) {
int x = Native.getLastError();
throw new IllegalStateException(
"error calling SetWindowsHookEx when installing machine-shutdown handler "
+ x);
}
System.out.println("Installed shutdown-detect hook procedure");
}
public static void main(String[] args) {
final JFrame frame = new JFrame("Shutdown Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
register(frame, new IShutdownListener() {
@Override
public void onShutdown() {
try {
PrintStream out = new PrintStream(new
File("C:/SCC_Runtime/shutdownTest.txt"));
System.out.println("shutting down");
out.println("shutting down");
out.close();
}
catch (IOException ex) {}
System.exit(1);
}
});
}
}
