WatchService實現監聽文件變化/含子目錄

package wds;

import java.io.*;
import java.nio.file.*;
import java.nio.file.attribute.*;
import java.nio.channels.*;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;

public class WatchFile
{
    public static void main(String[] args) 
            throws Exception{

        String filePath = ("D:");//直接監聽D盤

        // 獲取文件系統的WatchService對象
        WatchService watchService = FileSystems.getDefault().newWatchService();
        Paths.get(filePath).register(watchService 
                , StandardWatchEventKinds.ENTRY_CREATE
                , StandardWatchEventKinds.ENTRY_MODIFY
                , StandardWatchEventKinds.ENTRY_DELETE);

        File file = new File(filePath);
        LinkedList<File> fList = new LinkedList<File>();
        fList.addLast(file);
        while (fList.size() > 0 ) {
            File f = fList.removeFirst();
            if(f.listFiles() == null)
                continue;
            for(File file2 : f.listFiles()){
                    if (file2.isDirectory()){//下一級目錄
                    fList.addLast(file2);
                    //依次註冊子目錄
                    Paths.get(file2.getAbsolutePath()).register(watchService 
                            , StandardWatchEventKinds.ENTRY_CREATE
                            , StandardWatchEventKinds.ENTRY_MODIFY
                            , StandardWatchEventKinds.ENTRY_DELETE);
                }
            }
        }

        while(true)
        {
            // 獲取下一個文件改動事件
            WatchKey key = watchService.take();
            for (WatchEvent<?> event : key.pollEvents()) 
            {
                System.out.println(event.context() +" --> " + event.kind());
            }
            // 重設WatchKey
            boolean valid = key.reset();
            // 如果重設失敗，退出監聽
            if (!valid) 
            {
                break;
            }
        }
    }
}