如何查看文件夹和子文件夹的更改 [英] How to watch a folder and subfolders for changes

问题描述

我正在尝试查看特定文件夹的更改，然后，如果其中发生任何添加/修订/删除，我需要获取该文件夹及其子文件夹中所有文件的更改类型.我为此使用WatchService，但它仅监视单个路径，不处理子文件夹.

I´m trying to watch a specific folder for changes, and then if any addition/edition/removal happens inside of it, I need to get the change type of all files in that folder and its subfolders. I'm using WatchService for this but it only watches a single path, it doesn't handle subfolders.

这是我的方法:

try {
        WatchService watchService = pathToWatch.getFileSystem().newWatchService();
        pathToWatch.register(watchService, StandardWatchEventKinds.ENTRY_CREATE,
                StandardWatchEventKinds.ENTRY_MODIFY, StandardWatchEventKinds.ENTRY_DELETE);

        // loop forever to watch directory
        while (true) {
            WatchKey watchKey;
            watchKey = watchService.take(); // This call is blocking until events are present

            // Create the list of path files
            ArrayList<String> filesLog = new ArrayList<String>();
            if(pathToWatch.toFile().exists()) {
                File fList[] = pathToWatch.toFile().listFiles();
                for (int i = 0; i < fList.length; i++) { 
                    filesLog.add(fList[i].getName());
                }
            }

            // Poll for file system events on the WatchKey
            for (final WatchEvent<?> event : watchKey.pollEvents()) {
                printEvent(event);
            }

            // Save the log
            saveLog(filesLog);

            if(!watchKey.reset()) {
                System.out.println("Path deleted");
                watchKey.cancel();
                watchService.close();
                break;
            }
        }

    } catch (InterruptedException ex) {
        System.out.println("Directory Watcher Thread interrupted");
        return;
    } catch (IOException ex) {
        ex.printStackTrace();  // Loggin framework
        return;
    }

就像我之前说过的那样，我只获取所选路径中文件的日志，我想观看所有文件夹和子文件夹文件，例如:

Like I said before, I'm getting the log only for the files in the selected path, and I want to watch all folders and subfolders files, something like:

示例1:

FileA (Created)
FileB
FileC
FolderA FileE
FolderA FolderB FileF

示例2:

FileA
FileB (Modified)
FileC
FolderA FileE
FolderA FolderB FileF

有没有更好的解决方案?

Is there any better solution?

推荐答案

WatchService仅监视您注册的Path.它不会递归地通过这些路径.

A WatchService only watches the Paths you register. It does not go through those paths recursively.

给出/Root作为注册路径

/Root
    /Folder1
    /Folder2
        /Folder3

如果Folder3中有更改，它将无法捕获.

If there is a change in Folder3, it won't catch it.

您可以自己用递归方式注册目录路径

You can register the directory paths recursively yourself with

private void registerRecursive(final Path root) throws IOException {
    // register all subfolders
    Files.walkFileTree(root, new SimpleFileVisitor<Path>() {
        @Override
        public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) throws IOException {
            dir.register(watchService, ENTRY_CREATE, ENTRY_DELETE, ENTRY_MODIFY);
            return FileVisitResult.CONTINUE;
        }
    });
}

现在，WatchService将通知Path root的所有子文件夹中的所有更改，即.您传递的Path参数.

Now the WatchService will notify all changes in all subfolders of Path root, ie. the Path argument you pass.

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