如何在Java中的FileWacther中观看多个硬盘分区

Question

我使用FileWatcher来监视整个硬盘分区，在我的例子中是D驱动器，例如：D:：代码在我提供的一个路径下运行良好，我只想监视其他硬盘分区，以及C:，D:和E:如何实现这一点？下面是代码

public class FileWatcher {
    private final WatchService watcher;
    private final Map<WatchKey, Path> keys;
    static Logger log = LoggerFactory.getLogger(GitCloneRepo.class);

    /**
     * Creates a WatchService and registers the given directory
     */
    FileWatcher(Path dir) throws IOException {
        this.watcher = FileSystems.getDefault().newWatchService();
        this.keys = new HashMap<WatchKey, Path>();

        walkAndRegisterDirectories(dir);
    }

    /**
     * Register the given directory with the WatchService; This function will be called by FileVisitor
     */
    private void registerDirectory(Path dir) throws IOException
    {
        WatchKey key = dir.register(watcher, ENTRY_CREATE, ENTRY_DELETE, ENTRY_MODIFY);
        keys.put(key, dir);
    }

    /**
     * Register the given directory, and all its sub-directories, with the WatchService.
     */
    private void walkAndRegisterDirectories(final Path start) throws IOException {
        // register directory and sub-directories
        Files.walkFileTree(start, new SimpleFileVisitor<Path>() {
            @Override
            public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) throws IOException {
                registerDirectory(dir);
                return FileVisitResult.CONTINUE;
            }

            @Override
            public FileVisitResult visitFileFailed(Path file, IOException exc) throws IOException {
                if (exc instanceof AccessDeniedException) {
                    return FileVisitResult.SKIP_SUBTREE;
                }

                return super.visitFileFailed(file, exc);
            }
        });
    }

    /**
     * Process all events for keys queued to the watcher
     */
    void processEvents() {
        for (;;) {

            // wait for key to be signalled
            WatchKey key;
            try {
                key = watcher.take();
            } catch (InterruptedException x) {
                log.error("InterruptedException ",x);
                return;
            }

            Path dir = keys.get(key);
            if (dir == null) {
                log.warn("WatchKey not recognized!!");
                continue;
            }

            for (WatchEvent<?> event : key.pollEvents()) {
                @SuppressWarnings("rawtypes")
                WatchEvent.Kind kind = event.kind();

                // Context for directory entry event is the file name of entry
                @SuppressWarnings("unchecked")
                Path name = ((WatchEvent<Path>)event).context();
                Path child = dir.resolve(name);
                log.info("watching files");
                // print out event
                if (kind == ENTRY_MODIFY) {
                log.info("event.kind().name() {}: child {}", event.kind().name(), child);
                log.info("child {} ends with docx? {} ",child,child.endsWith(".docx"));
                String c= child.toString();
                log.info("**child {}***c.endsWith(.docx)"
                        + ""
                        + " {}",c,c.endsWith(".docx"));
                }
                // if directory is created, and watching recursively, then register it and its sub-directories
                if (kind == ENTRY_CREATE) {
                    try {
                        if (Files.isDirectory(child)) {
                            walkAndRegisterDirectories(child);
                        }
                    } catch (IOException x) {
                        // do something useful
                    }
                }
            }

            // reset key and remove from set if directory no longer accessible
            boolean valid = key.reset();
            if (!valid) {
                keys.remove(key);

                // all directories are inaccessible
                if (keys.isEmpty()) {
                    break;
                }
            }
        }
    }


 //working code
    public static void main(String[] args) throws IOException {
        try{
        Path dir = Paths.get("D:");
        FileWatcher fileWatcher=new FileWatcher(dir);
        fileWatcher.processEvents();
        }

        catch (AccessDeniedException xx) {
            log.error("AccessDeniedException  ",xx);
        }
         catch (FileSystemException x) {
            log.error("exception",x);
        }
        }

}

我看了这个问题但我似乎没有解决我的问题如何实现文件观察者观看多个目录

Answer 1

您的processEvents方法进入一个无限循环，在线程中断或路径消失之前不会返回，这意味着processEvents之后的任何代码在完成之前都不会执行。如果希望main方法启动多个观察程序，则需要从其他线程调用processEvents，例如使用Java 8:

// Create watchers
List<FileWatcher> watchers = new ArrayList<>();
try{
    watchers.add(new FileWatcher(Paths.get("D:")));
    watchers.add(new FileWatcher(Paths.get("E:")));
} catch (AccessDeniedException xx) {
    log.error("AccessDeniedException  ",xx);
} catch (FileSystemException x) {
    log.error("exception",x);
}

// Create and start threads
List<Thread> threads = watchers.stream()
        .map(w -> new Thread(w::processEvents))
        .peek(Thread::start)
        .collect(Collectors.toList());

使用Java 7：

// Create watchers
List<FileWatcher> watchers = new ArrayList<>();
try{
    watchers.add(new FileWatcher(Paths.get("D:")));
    watchers.add(new FileWatcher(Paths.get("E:")));
} catch (AccessDeniedException xx) {
    log.error("AccessDeniedException  ",xx);
} catch (FileSystemException x) {
    log.error("exception",x);
}

// Create and start threads
List<Thread> threads = new ArrayList<>();
for (FileWatcher watcher : watchers) {
    Thread thread = new Thread(new Runnable() {
        @Override
        public void run() {
            watcher.processEvents();
        }
    });
    thread.start();
    threads.add(thread);
}