blocks|key|1441519|text|在使用该文件的所有Java应用程序中使用一个FileLock，并让它们在同一个JVM中运行。否则，这将无法可靠地完成。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1441520|entityMap|0|LINK|mutability|MUTABLE|url|http://java.sun.com/javase/6/docs/api/java/nio/channels/FileLock.html^0|M|8|M|8|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@$9|O|A|P|B|C]]|D|@$9|Q|A|R|1|S]]|E|$]]|$1|F|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|G|$H|$5|I|J|K|E|$L|M]]]]

Use a <a href="http://java.sun.com/javase/6/docs/api/java/nio/channels/FileLock.html" rel="noreferrer"><code>FileLock</code></a> in all the Java applications using that file and have them run within the same JVM. Otherwise, this can't be done reliably.

blocks|key|1441580|text|如果多个进程(可以是Java和非Java的混合)可能正在使用该文件，请使用FileLock。成功使用文件锁的一个关键是记住它们只是“建议”。如果你检查它，锁肯定是可见的，但如果你忘记了，它不会阻止你对文件做一些事情。访问该文件的所有进程都应设计为使用锁定协议。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1441581|entityMap|0|LINK|mutability|MUTABLE|url|http://java.sun.com/j2se/1.5.0/docs/api/java/nio/channels/FileLock.html^0|11|8|11|8|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@$9|O|A|P|B|C]]|D|@$9|Q|A|R|1|S]]|E|$]]|$1|F|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|G|$H|$5|I|J|K|E|$L|M]]]]

If multiple processes (which can be a mix of Java and non-Java) might be using the file, use a <a href="http://java.sun.com/j2se/1.5.0/docs/api/java/nio/channels/FileLock.html" rel="nofollow noreferrer"><code>FileLock</code></a>. A key to using file locks successfully is to remember that they are only "advisory". The lock is guaranteed to be visible if you check for it, but it won't stop you from doing things to the file if you forget. All processes that access the file should be designed to use the locking protocol.

blocks|key|1226744|text|您可以尝试获得该文件的独占锁。只要不能获得排它锁，另一个程序就拥有该文件上的锁(排它锁或共享锁)。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1226745|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

You can try to get an exclusive lock on the file. As long as the exclusive lock cannot be obtained, another program has a lock (exclusive or shared) on the file.

blocks|key|1226757|text|应该可以在Windows中运行：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1226758|File+file+=+new+File("file.txt");
boolean+fileIsNotLocked+=+file.renameTo(file);|code-block|syntax|javascript|1226759|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Should work in Windows:

<pre><code>File file = new File("file.txt");
boolean fileIsNotLocked = file.renameTo(file);
</code></pre>

blocks|key|1226793|text|最好的方法是使用FileLock，但在我的例子(JDK1.6)中，我尝试了成功：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1226794|public+static+boolean+isFileUnlocked(File+file)+{
++++++++try+{
++++++++++++FileInputStream+in+=+new+FileInputStream(file);
++++++++++++if+(in!=null)+in.close();
++++++++++++return+true;
++++++++}+catch+(FileNotFoundException+e)+{
++++++++++++return+false;
++++++++}+catch+(Exception+e)+{
++++++++++++e.printStackTrace();
++++++++}

++++++++return+true;
++++}|code-block|syntax|javascript|1226795|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

The best way is to use FileLock, but in my case (jdk 1.6) I tried with success:

<pre><code>public static boolean isFileUnlocked(File file) {
 try {
 FileInputStream in = new FileInputStream(file);
 if (in!=null) in.close();
 return true;
 } catch (FileNotFoundException e) {
 return false;
 } catch (Exception e) {
 e.printStackTrace();
 }

 return true;
 }
</code></pre>

blocks|key|1441709|text|改进了Amjad+Abdul+Ghani的回答，我发现在尝试读取文件之前没有产生任何错误|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1441710|public+static+boolean+isFilelocked(File+file)+{
+++++try+{
+++++++++try+(FileInputStream+in+=+new+FileInputStream(file))+{
+++++++++++++in.read();
+++++++++++++return+false;
+++++++++}
+++++}+catch+(FileNotFoundException+e)+{
+++++++++return+file.exists();
+++++}+catch+(IOException+ioe)+{
+++++++++return+true;
+++++}
+}|code-block|syntax|javascript|1441711|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Improved Amjad Abdul-Ghani answer, I found that no error was produced until attempting to read from the file

<pre><code>public static boolean isFilelocked(File file) {
 try {
 try (FileInputStream in = new FileInputStream(file)) {
 in.read();
 return false;
 }
 } catch (FileNotFoundException e) {
 return file.exists();
 } catch (IOException ioe) {
 return true;
 }
 }
</code></pre>

blocks|key|1226869|text|我在可以访问Linux+Smb共享的windows上尝试了答案组合(@vlad)，这对我很有效。第一部分对于像Excel这样的锁来说已经足够了，但对于一些编辑器来说还不够。我添加了第二部分(重命名)来测试这两种情况。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1226870|public+static+boolean+testLockFile(File+p_fi)+{
++++boolean+bLocked+=+false;
++++try+(RandomAccessFile+fis+=+new+RandomAccessFile(p_fi,+"rw"))+{
++++++FileLock+lck+=+fis.getChannel().lock();
++++++lck.release();
++++}+catch+(Exception+ex)+{
++++++bLocked+=+true;
++++}
++++if+(bLocked)
++++++return+bLocked;
++++//+try+further+with+rename
++++String+parent+=+p_fi.getParent();
++++String+rnd+=+UUID.randomUUID().toString();
++++File+newName+=+new+File(parent+%2B+"/"+%2B+rnd);
++++if+(p_fi.renameTo(newName))+{
++++++newName.renameTo(p_fi);
++++}+else
++++++bLocked+=+true;
++++return+bLocked;
++}|code-block|syntax|javascript|1226871|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I tryed combination of answers (@vlad) on windows with access to Linux Smb share and it worked for me. The first part was enough for lock like Excel but not for some editors. I added second part (rename) for testing both situations.

<pre><code>public static boolean testLockFile(File p_fi) {
 boolean bLocked = false;
 try (RandomAccessFile fis = new RandomAccessFile(p_fi, "rw")) {
 FileLock lck = fis.getChannel().lock();
 lck.release();
 } catch (Exception ex) {
 bLocked = true;
 }
 if (bLocked)
 return bLocked;
 // try further with rename
 String parent = p_fi.getParent();
 String rnd = UUID.randomUUID().toString();
 File newName = new File(parent + "/" + rnd);
 if (p_fi.renameTo(newName)) {
 newName.renameTo(p_fi);
 } else
 bLocked = true;
 return bLocked;
 }
</code></pre>

blocks|key|1226909|text|对于Windows，您还可以使用：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1226910|new+RandomAccessFile(file,+"rw")|code-block|syntax|javascript|1226911|如果文件被独占锁定(例如被MS+Word锁定)，则会有一个异常：java.io.FileNotFoundException:+<fileName>+(The+process+cannot+access+the+file+because+it+is+being+used+by+another+process)。这样，您不需要仅仅为了检查而打开/关闭流。|offset|length|style|CODE|1226912|注意--如果文件不是独占锁定的(比如在Notepad%2B%2B中打开)，就不会有例外。|1226913|entityMap^0|0|0|W|3E|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@$I|T|J|U|K|L]]|9|@]|A|$]]|$1|M|3|N|5|6|7|V|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

For Windows, you can also use:

<pre><code>new RandomAccessFile(file, "rw")
</code></pre>

If the file is exclusively locked (by MS Word for example), there will be exception:
<code>java.io.FileNotFoundException: &lt;fileName&gt; (The process cannot access the file because it is being used by another process)</code>.
This way you do not need to open/close streams just for the check. 

Note - if the file is not exclusively locked (say opened in Notepad++) there will be no exception.

My Java program wants to read a file which can be locked by another program writing into it. I need to check if the file is locked and if so wait until it is free. How do I achieve this?

The Java program is running on a Windows 2000 server.

Check if a file is locked in Java

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我的Java程序想要读取一个文件，该文件可以被另一个写入文件的程序锁定。我需要检查文件是否被锁定，如果是，请等到它空闲。我该如何实现这一点？Java程序在Windows 2000服务器上运行。

问检查文件是否在Java中被锁定
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