UTC支持比较2个文件日期/时间

Question

我有一个实用程序比较源文件和目标文件的日期/时间。这在大多数情况下都适用，但在比较不同时区中文件的日期/时间时会失败。所以我需要一个UTC日期时间例程。

从环视看来，Windows API GetFileTime将支持这一点。我也发现这个包装程序，但它在Delphi 2010下编译时在GetFileTime调用上崩溃。

任何想法？或者是否有人有处理UTC时区等代码片段，我可以传递2个文件名，这将告诉我，如果他们不同？

function CompareFileTimes(File1, File2 : String) : LongInt; 
var 
    F1, F2   : THandle; 
    F1_CreateTime, 
    F1_LastAccess, 
    F1_LastWrite, 
    F2_CreateTime, 
    F2_LastAccess, 
    F2_LastWrite : PFileTime; 
begin 
    //Initialize all variables 
    F1 := 0; 
    F2 := 0; 

    //Since these are pointers, we have to 
    //allocate memory for the FileTime structures 
    GetMem(F1_CreateTime, SizeOf(TFileTime)); 
    GetMem(F1_LastAccess, SizeOf(TFileTime)); 
    GetMem(F1_LastWrite, SizeOf(TFileTime)); 
    GetMem(F2_CreateTime, SizeOf(TFileTime)); 
    GetMem(F2_LastAccess, SizeOf(TFileTime)); 
    GetMem(F2_LastWrite, SizeOf(TFileTime)); 

    //Fill the structures with nulls for now 
    FillChar(F1_CreateTime, SizeOf(TFileTime), #0); 
    FillChar(F1_LastAccess, SizeOf(TFileTime), #0); 
    FillChar(F1_LastWrite, SizeOf(TFileTime), #0); 
    FillChar(F2_CreateTime, SizeOf(TFileTime), #0); 
    FillChar(F2_LastAccess, SizeOf(TFileTime), #0); 
    FillChar(F2_LastWrite, SizeOf(TFileTime), #0); 

    //Get file handles for the files in question 
    //Notice that even though we're using CreateFile 
    //the open disposition for the file is OPEN_EXISTING 
    F1 := CreateFile(PChar(F1), 0, FILE_SHARE_READ, nil, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0); 
    F2 := CreateFile(PChar(F2), 0, FILE_SHARE_READ, nil, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0); 

    //Get the file times for the files. 
    GetFileTime(F1, F1_CreateTime, F1_LastAccess, F1_LastWrite); 
    GetFileTime(F2, F2_CreateTime, F2_LastAccess, F2_LastWrite); 

    //Assign the function's result to comparison 
    //-1, File1 is younger than File2 
    //0, File1 is the same as File2 
    //+1 File1 is older than File2 
    Result := CompareFileTime(F1_CreateTime^, F2_CreateTime^); 

    //Free the memory allocated to the pointers 
    FreeMem(F1_CreateTime, SizeOf(TFileTime)); 
    FreeMem(F1_LastAccess, SizeOf(TFileTime)); 
    FreeMem(F1_LastWrite, SizeOf(TFileTime)); 
    FreeMem(F2_CreateTime, SizeOf(TFileTime)); 
    FreeMem(F2_LastAccess, SizeOf(TFileTime)); 
    FreeMem(F2_LastWrite, SizeOf(TFileTime)); 
end; 

任何帮助将不胜感激。

Answer 1

德尔福2010年已经包含一个简单的包装获取UTC时间在ioutils.pas。这是一段比较文件的UTC创建时间的代码。

uses 
    IOUtils, DateUtils; 

function CompareFileCreationTimeUtc(const aFile1, aFile2: String): integer; 
var 
    lCreationTime1: TDateTime; 
    lCreationTime2: TDateTime; 
begin 

    lCreationTime1 := TFile.GetCreationTimeUtc(aFile1); 
    lCreationTime2 := TFile.GetCreationTimeUtc(aFile2); 

    Result := CompareDateTime(lCreationTime1, lCreationTime2); 

end; 

Answer 2

如果你不想使用IOUtils常规，喜欢自己做，你的函数应该予以纠正像（未经测试）：

function CompareFileTimes(File1, File2 : String) : LongInt; 
var 
    F1, F2: THandle; 
    F1_CreateTime, F2_CreateTime: TFileTime; 
begin 
    //Fill the structures with nulls for now 
    ZeroMemory(@F1_CreateTime, SizeOf(TFileTime)); 
    ZeroMemory(@F2_CreateTime, SizeOf(TFileTime)); 

    //Get file handles for the files in question 
    //Notice that even though we're using CreateFile 
    //the open disposition for the file is OPEN_EXISTING 
    F1 := CreateFile(PChar(File1), 0, FILE_SHARE_READ , nil, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0); 
    F2 := CreateFile(PChar(File2), 0, FILE_SHARE_READ, nil, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0); 

    if (F1=INVALID_HANDLE_VALUE) or (F1=INVALID_HANDLE_VALUE) then 
    RaiseLastOSError; 

    //Get the file times for the files. 
    if not GetFileTime(F1, @F1_CreateTime, nil, nil) or 
    not GetFileTime(F2, @F2_CreateTime, nil, nil) then 
    RaiseLastOSError; 
    //Assign the function's result to comparison 
    //-1, File1 is younger than File2 
    //0, File1 is the same as File2 
    //+1 File1 is older than File2 
    Result := CompareFileTime(F1_CreateTime, F2_CreateTime); 
end;