中途结束程序

Question

pythoncom.PumpMessages()

根据我的理解，这行代码基本上是让程序一直等待，直到有事情发生。对我来说，这样的效果是可以的。不过，我希望能在合适的情况下结束这个程序。请问怎么才能结束上面这行代码，或者让程序停止继续运行呢？

Answer 1

我想补充一下Gregg和Boaz Yaniv的两个回答。通常情况下，你会在一个单独的线程中运行阻塞代码，所以你需要向这个线程发送WM_QUIT消息。正如Gregg提到的，你应该使用PostQuitMessage，但这个方法只在当前线程中有效。你不应该使用PostThreadMessage来发送WM_QUIT消息（我记不清在哪看到过这个说明了）。你可以在讨论中了解更多内容，标题是"为什么有一个特殊的PostQuitMessage函数？"。我认为最好是先向线程发送WM_CLOSE消息。

# if more hotkeys needs to be supported at the same time this class needs to be rewritten
class HotKey:
    def __init__(self, modifier_key, virtual_key, callback):
        self.hotkey_id = 1
        # shared variable to pass thread id
        self.pid = mpdummy.Value('l', 0)

        # start checking hotkey press in new thread
        self.process_pool = mpdummy.Pool()
        self.process_pool.apply_async(HotKey.register, (self.hotkey_id, self.pid, modifier_key, virtual_key, callback, ))
        self.process_pool.close()

    # bind windows global hotkey
    @staticmethod
    def register(hotkey_id, pid, modifier_key, virtual_key, callback):
        # set thread ID to shared variable
        # Win API could also be used:
        # ctypes.windll.Kernel32.GetCurrentThreadId()
        pid.value = mpdummy.current_process().ident

        # register hotkey with Win API
        logging.getLogger('default').info("Registering hotkey with id " + str(hotkey_id) + " for key " + str(modifier_key) + " " + str(virtual_key))
        if not ctypes.windll.user32.RegisterHotKey(None, hotkey_id, modifier_key, virtual_key):
            logging.getLogger('default').info("Unable to register hotkey with id " + str(hotkey_id))

        msg = ctypes.wintypes.MSG()
        try:
            # wait for a message - it doesn't return until some message arrives
            while ctypes.windll.user32.GetMessageA(ctypes.byref(msg), None, 0, 0) != 0:
                # WM_HOTKEY     0x0312
                # https://msdn.microsoft.com/en-us/library/windows/desktop/ms646279(v=vs.85).aspx
                if msg.message == 0x0312:
                    logging.getLogger('default').info("Pressed hotkey with id " + str(hotkey_id))
                    callback()
                # WM_CLOSE
                # https://msdn.microsoft.com/en-us/library/windows/desktop/ms632617(v=vs.85).aspx
                elif msg.message == 0x0010:
                    # quit current thread
                    # WM_QUIT shouldn't be send with PostThreadMessageA therefore we send WM_CLOSE and quit inside thread.
                    # More info at:
                    # https://msdn.microsoft.com/en-us/library/windows/desktop/ms644945(v=vs.85).aspx
                    # https://blogs.msdn.microsoft.com/oldnewthing/20051104-33/?p=33453
                    ctypes.windll.user32.PostQuitMessage(0)
                ctypes.windll.user32.TranslateMessage(ctypes.byref(msg))
                ctypes.windll.user32.DispatchMessageA(ctypes.byref(msg))
        finally:
            logging.getLogger('default').info("Unregistering hotkey for id " + str(hotkey_id))
            ctypes.windll.user32.UnregisterHotKey(None, hotkey_id)

    def unregister(self):
        # send WM_CLOSE signal to thread checking for messages
        # WM_CLOSE      0x0010
        # https://msdn.microsoft.com/en-us/library/windows/desktop/ms632617(v=vs.85).aspx
        ctypes.windll.user32.PostThreadMessageA(self.pid.value, 0x0010, 0, 0)
        # wait for thread to finish
        self.process_pool.join()

我在使用这个功能来注册热键，但原理是一样的。这个类可以这样调用：

# bind global hotkey for "pressing" start/split button
# MOD_ALT       0x0001
# VK_F12        0x7B
# https://msdn.microsoft.com/en-us/library/windows/desktop/ms646309(v=vs.85).aspx
# https://msdn.microsoft.com/en-us/library/windows/desktop/dd375731.aspx
self.hotkey = hotkey.HotKey(0x0001, 0x7B, self.special_key_pressed)

当你想结束等待消息时，调用：

self.hotkey.unregister()

Answer 2

这里有一个使用定时器线程退出应用程序的例子：

import win32api
import win32con
import pythoncom
from threading import Timer

main_thread_id = win32api.GetCurrentThreadId()

def on_timer():
    win32api.PostThreadMessage(main_thread_id, win32con.WM_QUIT, 0, 0);

t = Timer(5.0, on_timer) # Quit after 5 seconds
t.start()

pythoncom.PumpMessages()

PostQuitMessage() 这个函数只能在主线程中使用，但主线程如果被“阻塞”了，就没什么用处了。你只能在把自己的消息处理方式接入消息循环时才能用它。

Answer 3

根据这些文档，pythoncom.PumpMessages()的意思是：

它会处理当前线程的所有消息，直到收到一个WM_QUIT消息为止。

所以，停止接收消息的一种方法是通过使用ctypes库来发送一个WM_QUIT消息到消息队列，这样可以调用PostQuitMessage：

ctypes.windll.user32.PostQuitMessage(0)