捕获目录内发生的事件

我正在使用Java 7 nio WatchService通过使用以下方法观看目录。

 Path myDir = Paths.get("/rootDir"); try { WatchService watcher = myDir.getFileSystem().newWatchService(); myDir.register(watcher, StandardWatchEventKinds.ENTRY_CREATE, StandardWatchEventKinds.ENTRY_DELETE, StandardWatchEventKinds.ENTRY_MODIFY); WatchKey watckKey = watcher.take(); List<WatchEvent> events = watckKey.pollEvents(); for (WatchEvent event : events) { if (event.kind() == StandardWatchEventKinds.ENTRY_CREATE) { System.out.println("Created: " + event.context().toString()); JOptionPane.showMessageDialog(null,"Created: " + event.context().toString()); } if (event.kind() == StandardWatchEventKinds.ENTRY_DELETE) { System.out.println("Delete: " + event.context().toString()); JOptionPane.showMessageDialog(null,"Delete: " + event.context().toString()); } if (event.kind() == StandardWatchEventKinds.ENTRY_MODIFY) { System.out.println("Modify: " + event.context().toString()); JOptionPane.showMessageDialog(null,"Modify: " + event.context().toString()); } } } catch (Exception e) { System.out.println("Error: " + e.toString()); } 

但是上述方法只响应一个事件发生在目录中，之后观察者没有响应该文件夹中发生的事件。 有没有办法我可以修改它来捕获文件夹内发生的所有事件。 我也想修改它来捕获子文件夹中发生的事件。 有人可以帮助我。

谢谢。

Answer 1

使用Apache Commons IO文件监控
它还将捕获子文件夹中发生的事件

 import java.io.File; import java.io.IOException; import org.apache.commons.io.monitor.FileAlterationListener; import org.apache.commons.io.monitor.FileAlterationListenerAdaptor; import org.apache.commons.io.monitor.FileAlterationMonitor; import org.apache.commons.io.monitor.FileAlterationObserver; public class Monitor { public Monitor() { } //path to a folder you are monitoring . public static final String FOLDER = MYPATH; public static void main(String[] args) throws Exception { System.out.println("monitoring started"); // The monitor will perform polling on the folder every 5 seconds final long pollingInterval = 5 * 1000; File folder = new File(FOLDER); if (!folder.exists()) { // Test to see if monitored folder exists throw new RuntimeException("Directory not found: " + FOLDER); } FileAlterationObserver observer = new FileAlterationObserver(folder); FileAlterationMonitor monitor = new FileAlterationMonitor(pollingInterval); FileAlterationListener listener = new FileAlterationListenerAdaptor() { // Is triggered when a file is created in the monitored folder @Override public void onFileCreate(File file) { // "file" is the reference to the newly created file System.out.println("File created: "+ file.getCanonicalPath()); } // Is triggered when a file is deleted from the monitored folder @Override public void onFileDelete(File file) { try { // "file" is the reference to the removed file System.out.println("File removed: "+ file.getCanonicalPath()); // "file" does not exists anymore in the location System.out.println("File still exists in location: "+ file.exists()); } catch (IOException e) { e.printStackTrace(System.err); } } }; observer.addListener(listener); monitor.addObserver(observer); monitor.start(); } } 

Answer 2

来自WatchService的JavaDoc ：

Watchable对象通过调用其register方法向watch服务注册，返回WatchKey来表示注册。 当检测到对象的事件时，发信号通知密钥，如果当前没有信号通知，则将其排队到监视服务，以便调用该轮询的消费者可以检索该密钥，或者采取方法来检索密钥和处理事件。 一旦处理了事件，消费者就会调用密钥的重置方法来重置密钥，该密钥允许密钥发出信号并与其他事件一起重新排队。

你只需要调用watcher.take()一次。

要观察更多事件，必须在使用WatchEvent后调用watchKey.reset() 。 将所有这些放在一个循环中。

 while (true) { WatchKey watckKey = watcher.take(); List> events = watckKey.pollEvents(); for (WatchEvent event : events) { // process event } watchKey.reset(); } 

另请参阅Java教程的相关部分 。