java使用WatchService监控文件夹示例

packageservice;

importconfig.Config;

importjava.io.IOException;

importjava.nio.file.*;

importjava.util.List;

importjava.util.concurrent.TimeUnit;

publicclassWatchDirService {

  privateWatchService watchService;

  privatebooleannotDone =true;

  publicWatchDirService(String dirPath){

    init(dirPath);

  }

  privatevoidinit(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();

    }

  }

  publicvoidstart(){

    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> 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 ev = event;

            Path path = ev.context();

            if(kind == StandardWatchEventKinds.ENTRY_CREATE){

              System.out.println("create "+ path.getFileName());

            }elseif(kind == StandardWatchEventKinds.ENTRY_MODIFY){

              System.out.println("modify "+ path.getFileName());

            }elseif(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;

      }

    }

  }

}