如何使用Java发现文件的创建时间？

Question

有没有一种简单的方法来发现使用Java创建文件的创建时间？File类只有一个获取"上次修改"时间的方法.根据我在Google上找到的一些资源,File类不提供getCreationTime()方法,因为并非所有文件系统都支持创建时的想法.

唯一可行的解​​决方案是我发现involes炮轰命令行并执行"dir"命令,看起来它输出文件的创建时间.我猜这个有用,我只需要支持Windows,但它似乎很容易让我感到错误.

是否有任何第三方图书馆提供我需要的信息？

更新:最后,我不认为购买第三方库对我来说是值得的,但他们的API看起来确实不错,所以对于有这个问题的其他人来说这可能是一个不错的选择.

Answer 1

随着Java 7的发布,有一种内置的方法可以做到这一点:

Path path = Paths.get("path/to/file");
BasicFileAttributes attributes = Files.readAttributes(path, BasicFileAttributes.class);
FileTime creationTime = attributes.creationTime();

值得注意的是,并非所有操作系统都提供此信息.我相信在这些实例中,它返回mtime,这是最后修改的时间.

Windows确实提供了创建时间.

Answer 2

我前几天写了一个小测试课,希望它可以帮到你:

// Get/Set windows file CreationTime/LastWriteTime/LastAccessTime
// Test with jna-3.2.7
// [http://maclife.net/wiki/index.php?title=Java_get_and_set_windows_system_file_creation_time_via_JNA_(Java_Native_Access)][1]

import java.io.*;
import java.nio.*;
import java.util.Date;

// Java Native Access library: jna.dev.java.net
import com.sun.jna.*;
import com.sun.jna.ptr.*;
import com.sun.jna.win32.*;
import com.sun.jna.platform.win32.*;

public class WindowsFileTime
{
    public static final int GENERIC_READ = 0x80000000;
    //public static final int GENERIC_WRITE = 0x40000000;   // defined in com.sun.jna.platform.win32.WinNT
    public static final int GENERIC_EXECUTE = 0x20000000;
    public static final int GENERIC_ALL = 0x10000000;

    // defined in com.sun.jna.platform.win32.WinNT
    //public static final int CREATE_NEW = 1;
    //public static final int CREATE_ALWAYS = 2;
    //public static final int OPEN_EXISTING = 3;
    //public static final int OPEN_ALWAYS = 4;
    //public static final int TRUNCATE_EXISTING = 5;

    public interface MoreKernel32 extends Kernel32
    {
        static final MoreKernel32 instance = (MoreKernel32)Native.loadLibrary ("kernel32", MoreKernel32.class, W32APIOptions.DEFAULT_OPTIONS);
        boolean GetFileTime (WinNT.HANDLE hFile, WinBase.FILETIME lpCreationTime, WinBase.FILETIME lpLastAccessTime, WinBase.FILETIME lpLastWriteTime);
        boolean SetFileTime (WinNT.HANDLE hFile, final WinBase.FILETIME lpCreationTime, final WinBase.FILETIME lpLastAccessTime, final WinBase.FILETIME lpLastWriteTime);
    }

    static MoreKernel32 win32 = MoreKernel32.instance;
    //static Kernel32 _win32 = (Kernel32)win32;

    static WinBase.FILETIME _creationTime = new WinBase.FILETIME ();
    static WinBase.FILETIME _lastWriteTime = new WinBase.FILETIME ();
    static WinBase.FILETIME _lastAccessTime = new WinBase.FILETIME ();

    static boolean GetFileTime (String sFileName, Date creationTime, Date lastWriteTime, Date lastAccessTime)
    {
        WinNT.HANDLE hFile = OpenFile (sFileName, GENERIC_READ);    // may be WinNT.GENERIC_READ in future jna version.
        if (hFile == WinBase.INVALID_HANDLE_VALUE) return false;

        boolean rc = win32.GetFileTime (hFile, _creationTime, _lastAccessTime, _lastWriteTime);
        if (rc)
        {
            if (creationTime != null) creationTime.setTime (_creationTime.toLong());
            if (lastAccessTime != null) lastAccessTime.setTime (_lastAccessTime.toLong());
            if (lastWriteTime != null) lastWriteTime.setTime (_lastWriteTime.toLong());
        }
        else
        {
            int iLastError = win32.GetLastError();
            System.out.print ("?????????????" + iLastError + " " + GetWindowsSystemErrorMessage (iLastError));
        }
        win32.CloseHandle (hFile);
        return rc;
    }
    static boolean SetFileTime (String sFileName, final Date creationTime, final Date lastWriteTime, final Date lastAccessTime)
    {
        WinNT.HANDLE hFile = OpenFile (sFileName, WinNT.GENERIC_WRITE);
        if (hFile == WinBase.INVALID_HANDLE_VALUE) return false;

        ConvertDateToFILETIME (creationTime, _creationTime);
        ConvertDateToFILETIME (lastWriteTime, _lastWriteTime);
        ConvertDateToFILETIME (lastAccessTime, _lastAccessTime);

        //System.out.println ("creationTime: " + creationTime);
        //System.out.println ("lastWriteTime: " + lastWriteTime);
        //System.out.println ("lastAccessTime: " + lastAccessTime);

        //System.out.println ("_creationTime: " + _creationTime);
        //System.out.println ("_lastWriteTime: " + _lastWriteTime);
        //System.out.println ("_lastAccessTime: " + _lastAccessTime);

        boolean rc = win32.SetFileTime (hFile, creationTime==null?null:_creationTime, lastAccessTime==null?null:_lastAccessTime, lastWriteTime==null?null:_lastWriteTime);
        if (! rc)
        {
            int iLastError = win32.GetLastError();
            System.out.print ("?????????????" + iLastError + " " + GetWindowsSystemErrorMessage (iLastError));
        }
        win32.CloseHandle (hFile);
        return rc;
    }
    static void ConvertDateToFILETIME (Date date, WinBase.FILETIME ft)
    {
        if (ft != null)
        {
            long iFileTime = 0;
            if (date != null)
            {
                iFileTime = WinBase.FILETIME.dateToFileTime (date);
                ft.dwHighDateTime = (int)((iFileTime >> 32) & 0xFFFFFFFFL);
                ft.dwLowDateTime = (int)(iFileTime & 0xFFFFFFFFL);
            }
            else
            {
                ft.dwHighDateTime = 0;
                ft.dwLowDateTime = 0;
            }
        }
    }

    static WinNT.HANDLE OpenFile (String sFileName, int dwDesiredAccess)
    {
        WinNT.HANDLE hFile = win32.CreateFile (
            sFileName,
            dwDesiredAccess,
            0,
            null,
            WinNT.OPEN_EXISTING,
            0,
            null
            );
        if (hFile == WinBase.INVALID_HANDLE_VALUE)
        {
            int iLastError = win32.GetLastError();
            System.out.print (" ???????????" + iLastError + " " + GetWindowsSystemErrorMessage (iLastError));
        }
        return hFile;
    }
    static String GetWindowsSystemErrorMessage (int iError)
    {
        char[] buf = new char[255];
        CharBuffer bb = CharBuffer.wrap (buf);
        //bb.clear ();
        //PointerByReference pMsgBuf = new PointerByReference ();
        int iChar = win32.FormatMessage (
                WinBase.FORMAT_MESSAGE_FROM_SYSTEM
                    //| WinBase.FORMAT_MESSAGE_IGNORE_INSERTS
                    //|WinBase.FORMAT_MESSAGE_ALLOCATE_BUFFER
                    ,
                null,
                iError,
                0x0804,
                bb, buf.length,
                //pMsgBuf, 0,
                null
            );
        //for (int i=0; i<iChar; i++)
        //{
        //  System.out.print (" ");
        //  System.out.print (String.format("%02X", buf[i]&0xFFFF));
        //}
        bb.limit (iChar);
        //System.out.print (bb);
        //System.out.print (pMsgBuf.getValue().getString(0));
        //win32.LocalFree (pMsgBuf.getValue());
        return bb.toString ();
    }

    public static void main (String[] args) throws Exception
    {
        if (args.length == 0)
        {
            System.out.println ("?? Windows ?????????????????????????");
            System.out.println ("???");
            System.out.println ("   java -cp .;..;jna.jar;platform.jar WindowsFileTime [???1] [???2]...");
            return;
        }

        boolean rc;
        java.sql.Timestamp ct = new java.sql.Timestamp(0);
        java.sql.Timestamp wt = new java.sql.Timestamp(0);
        java.sql.Timestamp at = new java.sql.Timestamp(0);

        for (String sFileName : args)
        {
            System.out.println ("?? " + sFileName);

            rc = GetFileTime (sFileName, ct, wt, at);
            if (rc)
            {
                System.out.println ("   ?????" + ct);
                System.out.println ("   ?????" + wt);
                System.out.println ("   ?????" + at);
            }
            else
            {
                //System.out.println ("GetFileTime ??");
            }


            //wt.setTime (System.currentTimeMillis());
            wt = java.sql.Timestamp.valueOf("2010-07-23 00:00:00");
            rc = SetFileTime (sFileName, null, wt, null);
            if (rc)
            {
                System.out.println ("SetFileTime (??????) ??");
            }
            else
            {
                //System.out.println ("SetFileTime ??");
            }
        }
    }
}

Answer 3

我喜欢jGuru上的答案，它列出了使用JNI来获取答案的选项。事实证明，这可能比掏钱更快，并且您可能会遇到其他情况，例如需要专门针对 Windows 实现的情况。

另外，如果您需要移植到不同的平台，那么您也可以移植您的库，并让它返回 -1 作为 *ix 上这个问题的答案。