使用 Watch Service API 觀察檔案系統

 1 package idv.steven.nio2;
 2 
 3 import java.io.IOException;
 4 import java.nio.file.FileSystems;
 5 import java.nio.file.Path;
 6 import java.nio.file.Paths;
 7 import java.nio.file.StandardWatchEventKinds;
 8 import java.nio.file.WatchEvent;
 9 import java.nio.file.WatchKey;
10 import java.nio.file.WatchService;
11 
12 public class WatchFile {
13     
14     public void run() {
15         final Path path = Paths.get("D:/temp");
16         WatchService watchService;
17         try {
18             watchService = FileSystems.getDefault().newWatchService();
19             
20             path.register(watchService, StandardWatchEventKinds.ENTRY_CREATE,
21                     StandardWatchEventKinds.ENTRY_MODIFY, StandardWatchEventKinds.ENTRY_DELETE);
22 
23             while (true) {
24                 final WatchKey key = watchService.take();
25                 
26                 for (WatchEvent> watchEvent : key.pollEvents()) {
27                     final WatchEvent watchEventPath = (WatchEvent) watchEvent;
28                     final Path filename = watchEventPath.context();
29                     
30                     System.out.println("kind: " + watchEvent.kind().toString());
31                     System.out.println("filename: " + filename.toString());
32                 }
33                 
34                 break;
35             }
36 
37             watchService.close();
38             System.out.println("exit");
39         } catch (IOException | InterruptedException e) {
40             e.printStackTrace();
41         }
42     }
43 
44     public static void main(String[] args) {
45         new WatchFile().run();
46     }
47 }