如何使用 Java 发现文件的创建时间？
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How to discover a File's creation time with Java?
提问by Outlaw Programmer
Is there an easy way to discover a File's creation time with Java? The File class only has a method to get the "last modified" time. According to some resources I found on Google, the File class doesn't provide a getCreationTime() method because not all file systems support the idea of a creation time.
有没有一种简单的方法可以用 Java 发现文件的创建时间？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间的概念。
The only working solution I found involes shelling out the the command line and executing the "dir" command, which looks like it outputs the file's creation time. I guess this works, I only need to support Windows, but it seems very error prone to me.
我发现的唯一可行的解决方案是退出命令行并执行“dir”命令，它看起来像是输出文件的创建时间。我想这行得通，我只需要支持 Windows，但对我来说似乎很容易出错。
Are there any third party libraries that provide the info I need?
是否有任何第三方库可以提供我需要的信息？
Update:In the end, I don't think it's worth it for me to buy the third party library, but their API does seem pretty good so it's probably a good choice for anyone else that has this problem.
更新：最后，我认为购买第三方库对我来说不值得，但他们的 API 看起来确实不错，因此对于遇到此问题的其他人来说，这可能是一个不错的选择。
回答by Joseph Gordon
I like the answer on jGuruthat lists the option of using JNIto get the answer. This might prove to be faster than shelling out and you may encounter other situations such as this that need to be implemented specifically for windows.
我喜欢jGuru上的答案，其中列出了使用JNI获得答案的选项。这可能证明比炮击更快，并且您可能会遇到其他情况，例如需要专门为 Windows 实现的情况。
Also, if you ever need to port to a different platform, then you can port your library as well and just have it return -1 for the answer to this question on *ix.
此外，如果您需要移植到不同的平台，那么您也可以移植您的库，只需让它返回 -1 即可在 *ix 上回答这个问题。
回答by Mike Houston
I've been investigating this myself, but I need something that will work across Windows/*nix platforms.
我自己一直在调查这个，但我需要一些可以跨 Windows/*nix 平台工作的东西。
One SO post includes some links to Posix JNI implementations.
一篇 SO 帖子包含一些指向Posix JNI 实现的链接。
In particular, JNA-POSIX implements methods for getting file statswith implementations for Windows, BSD, Solaris, Linux and OSX.
特别是，JNA-POSIX 实现了获取文件统计信息的方法，这些方法适用于Windows、BSD、Solaris、Linux 和 OSX。
All in all it looks very promising, so I'll be trying it out on my own project very soon.
总而言之，它看起来非常有前途，所以我很快就会在我自己的项目中尝试它。
回答by u404192
I've wrote a small test class some days ago, wish it can help you:
前几天写了一个小测试类，希望可以帮到你：
// 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 ("获取文件时间失败，错误码：" + 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 ("设置文件时间失败，错误码：" + 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 (" 打开文件失败，错误码：" + 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 ("获取 Windows 的文件时间（创建时间、最后修改时间、最后访问时间）");
System.out.println ("用法：");
System.out.println (" java -cp .;..;jna.jar;platform.jar WindowsFileTime [文件名1] [文件名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 ("文件 " + sFileName);
rc = GetFileTime (sFileName, ct, wt, at);
if (rc)
{
System.out.println (" 创建时间：" + ct);
System.out.println (" 修改时间：" + wt);
System.out.println (" 访问时间：" + at);
}
else
{
//System.out.println ("GetFileTime 失败");
}
//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 (最后修改时间) 成功");
}
else
{
//System.out.println ("SetFileTime 失败");
}
}
}
}
回答by Kamal
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
public class CreateDateInJava {
public static void main(String args[]) {
try {
// get runtime environment and execute child process
Runtime systemShell = Runtime.getRuntime();
BufferedReader br1 = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter filename: ");
String fname = (String) br1.readLine();
Process output = systemShell.exec("cmd /c dir \"" + fname + "\" /tc");
System.out.println(output);
// open reader to get output from process
BufferedReader br = new BufferedReader(new InputStreamReader(output.getInputStream()));
String out = "";
String line = null;
int step = 1;
while ((line = br.readLine()) != null) {
if (step == 6) {
out = line;
}
step++;
}
// display process output
try {
out = out.replaceAll(" ", "");
System.out.println("CreationDate: " + out.substring(0, 10));
System.out.println("CreationTime: " + out.substring(10, 16) + "m");
} catch (StringIndexOutOfBoundsException se) {
System.out.println("File not found");
}
} catch (IOException ioe) {
System.err.println(ioe);
} catch (Throwable t) {
t.printStackTrace();
}
}
}
/**
D:\Foldername\Filename.Extension
Ex:
Enter Filename :
D:\Kamal\Test.txt
CreationDate: 02/14/2011
CreationTime: 12:59Pm
*/
回答by Peter
The javaxt-corelibrary includes a File class that can be used to retrieve file attributes, including the creation time. Example:
该javaxt核心库包括可用于检索的文件属性，包括创建时间，文件类。例子：
javaxt.io.File file = new javaxt.io.File("/temp/file.txt");
System.out.println("Created: " + file.getCreationTime());
System.out.println("Accessed: " + file.getLastAccessTime());
System.out.println("Modified: " + file.getLastModifiedTime());
Works with Java 1.5 and up.
适用于 Java 1.5 及更高版本。
回答by ajon
With the release of Java 7 there is a built-in way to do this:
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();
It is important to note that not all operating systems provide this information. I believe in those instances this returns the mtime which is the last modified time.
请务必注意，并非所有操作系统都提供此信息。我相信在这些情况下，这会返回最后修改时间的 mtime。
Windows does provide creation time.
Windows 确实提供了创建时间。
回答by Jorgesys
This is a basic example in Java, using BasicFileAttributesclass:
这是 中的一个基本示例Java，使用BasicFileAttributes类：
Path path = Paths.get("C:\Users\jorgesys\workspaceJava\myfile.txt");
BasicFileAttributes attr;
try {
attr = Files.readAttributes(path, BasicFileAttributes.class);
System.out.println("File creation time: " + attr.creationTime());
} catch (IOException e) {
System.out.println("oops un error! " + e.getMessage());
}
