摘要
用户的一个误操作往往会引起Windows系统的退出,正运行中的程序的数据也因此丢失,为了提高我们程序的健壮性,下面我们来说说 Windows 关机消息的截获原理 在Windows关机或注销的时候会给每个进程传送一个WM_QUERYENDSESSION消息,如果中间有的进程不能顺利的结束,这时该信息执行的结果将返回FALSE,这时Windows将不再继续向后面的进程发送WM_QUERYENDSESSION消息,只有所有的进程都可以顺利的结束,才代表顺利结束. 不管WM_QUERYENDSESSION消息最后是否可以顺利结束,Windows会再向所有的进程传送WM_ENDSESSION消息,而wParam的内容指出是否可以顺利结束如果返回FALSE则Windows将不会退出实例
#include /*Dev-C++编译*/
/* Declare Windows procedure */LRESULT CALLBACK WindowProcedure (HWND, UINT, WPARAM, LPARAM);
/* Make the class name into a global variable */char szClassName[ ] = "WindowsApp";
int WINAPI WinMain (HINSTANCE hThisInstance, HINSTANCE hPrevInstance, LPSTR lpszArgument, int nFunsterStil){ HWND hwnd; /* This is the handle for our window */ MSG messages; /* Here messages to the application are saved */ WNDCLASSEX wincl; /* Data structure for the windowclass */
/* The Window structure */ wincl.hInstance = hThisInstance; wincl.lpszClassName = szClassName; wincl.lpfnWndProc = WindowProcedure; /* This function is called by windows */ wincl.style = CS_DBLCLKS; /* Catch double-clicks */ wincl.cbSize = sizeof (WNDCLASSEX);
/* Use default icon and mouse-pointer */ wincl.hIcon = LoadIcon (NULL, IDI_APPLICATION); wincl.hIconSm = LoadIcon (NULL, IDI_APPLICATION); wincl.hCursor = LoadCursor (NULL, IDC_ARROW); wincl.lpszMenuName = NULL; /* No menu */ wincl.cbClsExtra = 0; /* No extra bytes after the window class */ wincl.cbWndExtra = 0; /* structure or the window instance */ /* Use Windows’s default color as the background of the window */ wincl.hbrBackground = (HBRUSH) COLOR_BACKGROUND;
/* Register the window class, and if it fails quit the program */ if (!RegisterClassEx (&wincl)) return 0;
/* The class is registered, let’s create the program*/ hwnd = CreateWindowEx ( 0, /* Extended possibilites for variation */ szClassName, /* Classname */ "Windows App", /* Title Text */ WS_OVERLAPPEDWINDOW, /* default window */ CW_USEDEFAULT, /* Windows decides the position */ CW_USEDEFAULT, /* where the window ends up on the screen */ 544, /* The programs width */ 375, /* and height in pixels */ HWND_DESKTOP, /* The window is a child-window to desktop */ NULL, /* No menu */ hThisInstance, /* Program Instance handler */ NULL /* No Window Creation data */ );
/* Make the window visible on the screen */ ShowWindow (hwnd, nFunsterStil);
/* Run the message loop. It will run until GetMessage() returns 0 */ while (GetMessage (&messages, NULL, 0, 0)) { /* Translate virtual-key messages into character messages */ TranslateMessage(&messages); /* Send message to WindowProcedure */ DispatchMessage(&messages); }
/* The program return-value is 0 - The value that PostQuitMessage() gave */ return messages.wParam;}
/* This function is called by the Windows function DispatchMessage() */
LRESULT CALLBACK WindowProcedure (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam){ switch (message) /* handle the messages */ { case WM_DESTROY: PostQuitMessage (0); /* send a WM_QUIT to the message queue */ break; case WM_QUERYENDSESSION: /*如果要注销或关闭系统返回 1 否则返回 0 不管WM_QUERYENDSESSION最后的结果是可以顺利结束或不能顺利结束，Windows会再送 一个WM_ENDSESSION的信息给所有的Process，而wParam的内容便是指出是否可以顺利结束*/ return 0;//return 1; case WM_ENDSESSION: /*如果要注销或关闭系统返回 1 否则返回 0*/ return 0;//return 1; default: /* for messages that we don’t deal with */ return DefWindowProc (hwnd, message, wParam, lParam); }
return 0;}
