java - java中的文件锁定

Question

我有一个文件夹中的文件列表， 我想锁定一个特定的文件(用户向我发送要锁定的文件的名称)，我正在执行以下操作:

try {

    File file = new File("filename");
    FileChannel channel = new RandomAccessFile(file, "rw").getChannel();
    FileLock lock = channel.lock();
    try {
        lock = channel.tryLock();
    } catch (OverlappingFileLockException e) {
        // File is already locked 
    }

} catch (Exception e) {
}

如果另一个用户想要查看文件列表，我必须告诉他们哪些文件已锁定，哪些文件已解锁

   File folder = new File("E:\\folder_to_LIST_OF_FILES");
            File[] listOfFiles = folder.listFiles();

            for (int i = 0; i < listOfFiles.length; i++) {
                if (listOfFiles[i].isFile()) {
                    FilesDto returnDto = new FilesDto();
                    returnDto.setFileName(FilenameUtils.removeExtension(listOfFiles[i].getName()));

                    // Check File Status if file is Locked or unlocked

                    if (lock==null) {
                        returnDto.setStatus("unlocked");
                        returnDto.setFilePath(listOfFiles[i].getAbsolutePath());

                    } else {
                        returnDto.setStatus("Locked");
                    }

                    returnDtoList.add(returnDto);
                }
            }

这两个片段来自不同的 API。 如何检查文件的状态是锁定还是解锁？

Answer 1

documentation在 FileLock 类上说:

This file-locking API is intended to map directly to the native locking facility of the underlying operating system. Thus the locks held on a file should be visible to all programs that have access to the file, regardless of the language in which those programs are written.

所以看来您可以使用与第一个片段中相同的代码:

File folder = new File("E:\\folder_to_LIST_OF_FILES");
File[] listOfFiles = folder.listFiles();

for (int i = 0; i < listOfFiles.length; i++) {
    if (listOfFiles[i].isFile()) {
        FilesDto returnDto = new FilesDto();
        returnDto.setFileName(FilenameUtils.removeExtension(listOfFiles[i].getName()));

        File file = new File("filename");
        FileChannel channel = new RandomAccessFile(file, "rw").getChannel();
        FileLock lock;
        try {
            lock = channel.tryLock();
        } catch (OverlappingFileLockException e) {
            // File is already locked 
        }

        if (lock==null) {
            returnDto.setStatus("unlocked");
            returnDto.setFilePath(listOfFiles[i].getAbsolutePath());

        } else {
            lock.release();
            returnDto.setStatus("Locked");
        }

        returnDtoList.add(returnDto);
    }
}