代码运行后，可以实时监视用户计算机桌面上拥有焦点的窗口，如果焦点有切换就会给出提示。

from ctypes import *

from time import sleep

from datetime import datetime

#方便调用Windows底层API函数

user32 = windll.user32

kernel32 = windll.kernel32

psapi = windll.psapi

#实时查看当前窗口

def getProcessInfo():

    global windows

    #获取当前位于桌面最顶端的窗口句柄

    hwnd = user32.GetForegroundWindow()

    pid = c_ulong(0)

    #获取进程ID

    user32.GetWindowThreadProcessId(hwnd, byref(pid))

    processId = str(pid.value)

    #获取可执行文件名称

    executable = create_string_buffer(512)

    h_process = kernel32.OpenProcess(0x400|0x10, False, pid)

    psapi.GetModuleBaseNameA(h_process, None, byref(executable), 512)

    #获取窗口标题

    windowTitle = create_string_buffer(512)

    user32.GetWindowTextA(hwnd, byref(windowTitle), 512)

    #关闭句柄

    kernel32.CloseHandle(hwnd)

    kernel32.CloseHandle(h_process)

    #更新最近两个窗口的信息

    windows.pop(0)

    windows.append([executable.value.decode('gbk'),windowTitle.value.decode('gbk')])

def main():

    global windows

    windows = [None, None]

    while True:

        getProcessInfo()

        #如果用户切换窗口则进行提示

        if windows[0] != windows[1]:

            print('='*30)

            print(str(datetime.now())[:19],windows[0],'==>',windows[1])

        sleep(0.2)

if __name__ == '__main__':

    main()

部分运行结果如下：

2016-08-14 09:12:52 ['Explorer.EXE', ''] ==> ['pythonw.exe', 'focusSwitch.py - C:/Python35/focusSwitch.py (3.5.1)']

==============================

2016-08-14 09:12:56 ['pythonw.exe', 'focusSwitch.py - C:/Python35/focusSwitch.py (3.5.1)'] ==> ['QQBrowser.exe', '微信公众平台']

==============================

2016-08-14 09:13:11 ['QQBrowser.exe', '微信公众平台'] ==> ['Explorer.EXE', '']

==============================

2016-08-14 09:13:12 ['Explorer.EXE', ''] ==> ['pythonw.exe', '*Python 3.5.1 Shell*']

==============================

2016-08-14 09:13:22 ['pythonw.exe', '*Python 3.5.1 Shell*'] ==> ['Explorer.EXE', '']

==============================

2016-08-14 09:13:32 ['Explorer.EXE', ''] ==> ['pythonw.exe', '*Python 3.5.1 Shell*']

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