《WindowsAPI巡礼》---GetSystemTime和GetFileTime
FILETIME结构包含了文件或目录的日期和时间信息：（自1601年1月1日以来，单位为100纳秒）
typedef struct _FILETIME {
DWORD dwLowDateTime; //低32位
DWORD dwHighDateTime; //高32位
} FILETIME, *PFILETIME;
SYSTEMTIME结构包含了用户可识别的系统日期信息：
typedef struct _SYSTEMTIME {
WORD wYear;
WORD wMonth;
WORD wDayOfWeek;
WORD wDay;
WORD wHour;
WORD wMinute;
WORD wSecond;
WORD wMilliseconds;
} SYSTEMTIME, *PSYSTEMTIME;
=======================================================
函数FileTimeToSystemTime用来将文件时间格式转换为系统时间格式：
BOOL WINAPI FileTimeToSystemTime(
__in const FILETIME *lpFileTime, //文件时间
__out LPSYSTEMTIME lpSystemTime //系统时间
);
函数SystemTimeToFileTime则是将系统时间转换成文件时间格式：
BOOL WINAPI SystemTimeToFileTime(
__in const SYSTEMTIME *lpSystemTime,
__out LPFILETIME lpFileTime
);
将文件时间转换为系统时间的实例如下：
#include <windows.h>
// SetFileToCurrentTime - sets last write time to current system time
// Return value - TRUE if successful, FALSE otherwise
// hFile - must be a valid file handle
BOOL SetFileToCurrentTime(HANDLE hFile)
{
FILETIME ft;
SYSTEMTIME st;
BOOL f;
GetSystemTime(&st); // Gets the current system time
SystemTimeToFileTime(&st, &ft); // Converts the current system time to file time format
f = SetFileTime(hFile, // Sets last-write time of the file
(LPFILETIME) NULL, // to the converted current system time
(LPFILETIME) NULL,
&ft);
return f;
}
=======================================================
GetSystemTime函数用来获得系统时间：
void WINAPI GetSystemTime(
__out LPSYSTEMTIME lpSystemTime
);
GetFileTime函数用来获得一个文件或目录的创建的时间、最后访问的时间以及最后修改的时间：
BOOL WINAPI GetFileTime(
__in HANDLE hFile, //文件或目录句柄
__out_opt LPFILETIME lpCreationTime, //返回的创建的日期和时间信息
__out_opt LPFILETIME lpLastAccessTime, //返回的最后访问的日期和时间信息
__out_opt LPFILETIME lpLastWriteTime //返回的最后修改的日期和时间信息
);
返回值：成功时，返回非零值；失败时，返回零值。
下面的代码使用GetFileTime函数来获得文件的最后写入时间：
#include <windows.h>
#include <tchar.h>
#include <strsafe.h>
// GetLastWriteTime - Retrieves the last-write time and converts
// the time to a string
//
// Return value - TRUE if successful, FALSE otherwise
// hFile - Valid file handle
// lpszString - Pointer to buffer to receive string
BOOL GetLastWriteTime(HANDLE hFile, LPTSTR lpszString, DWORD dwSize)
{
FILETIME ftCreate, ftAccess, ftWrite;
SYSTEMTIME stUTC, stLocal;
DWORD dwRet;
// Retrieve the file times for the file.
if (!GetFileTime(hFile, &ftCreate, &ftAccess, &ftWrite))
return FALSE;
// Convert the last-write time to local time.
FileTimeToSystemTime(&ftWrite, &stUTC);
SystemTimeToTzSpecificLocalTime(NULL, &stUTC, &stLocal);
// Build a string showing the date and time.
dwRet = StringCchPrintf(lpszString, dwSize,
TEXT("%02d/%02d/%d %02d:%02d"),
stLocal.wMonth, stLocal.wDay, stLocal.wYear,
stLocal.wHour, stLocal.wMinute);
if( S_OK == dwRet )
return TRUE;
else return FALSE;
}
int _tmain(int argc, TCHAR *argv[])
{
HANDLE hFile;
TCHAR szBuf[MAX_PATH];
if( argc != 2 )
{
printf("This sample takes a file name as a parameter/n");
return 0;
}
hFile = CreateFile(argv[1], GENERIC_READ, FILE_SHARE_READ, NULL,
OPEN_EXISTING, 0, NULL);
if(hFile == INVALID_HANDLE_VALUE)
{
printf("CreateFile failed with %d/n", GetLastError());
return 0;
}
if(GetLastWriteTime( hFile, szBuf, MAX_PATH ))
_tprintf(TEXT("Last write time is: %s/n"), szBuf);
CloseHandle(hFile);
}