java使用WatchService监控文件夹示例

package service;import config.Config;import java.io.IOException;import java.nio.file.*;import java.util.List;import java.util.concurrent.TimeUnit;public class WatchDirService {  private WatchService watchService;  private boolean notDone = true;  public WatchDirService(String dirPath){    init(dirPath);  }  private void init(String dirPath) {    Path path = Paths.get(dirPath);    try {      watchService = FileSystems.getDefault().newWatchService(); //创建watchService      path.register(watchService,       StandardWatchEventKinds.ENTRY_CREATE,      StandardWatchEventKinds.ENTRY_MODIFY,      StandardWatchEventKinds.ENTRY_DELETE); //注册需要监控的事件,ENTRY_CREATE 文件创建,ENTRY_MODIFY 文件修改,ENTRY_MODIFY 文件删除    } catch (IOException e) {      e.printStackTrace();    }  }  public void start(){    System.out.print("watch...");    while (notDone){      try {        WatchKey watchKey = watchService.poll(Config.POLL_TIME_OUT, TimeUnit.SECONDS); //此处将处于等待状态,等待检测到文件夹下得文件发生改变,返回WatchKey对象        if(watchKey != null){          List<WatchEvent<?>> events = watchKey.pollEvents(); //获取所有得事件          for (WatchEvent event : events){            WatchEvent.Kind<?> kind = event.kind();             if (kind == StandardWatchEventKinds.OVERFLOW){              //当前磁盘不可用              continue;            }            WatchEvent<Path> ev = event;            Path path = ev.context();            if(kind == StandardWatchEventKinds.ENTRY_CREATE){              System.out.println("create " + path.getFileName());            }else if(kind == StandardWatchEventKinds.ENTRY_MODIFY){              System.out.println("modify " + path.getFileName());            }else if(kind == StandardWatchEventKinds.ENTRY_DELETE){              System.out.println("delete " + path.getFileName());            }          }          if(!watchKey.reset()){             //已经关闭了进程            System.out.println("exit watch server");            break;          }        }      } catch (InterruptedException e) {        e.printStackTrace();        return;      }    }  }}