《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);

}