《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);    
}