目录监控

• 增加maven依赖

        <dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>2.5</version>
        </dependency>

• 编写listener

public class FileListener extends FileAlterationListenerAdaptor {
    @Override
    public void onDirectoryCreate(File directory) {
        super.onDirectoryCreate(directory);
    }

    @Override
    public void onDirectoryChange(File directory) {
        super.onDirectoryChange(directory);
    }

    @Override
    public void onDirectoryDelete(File directory) {
        super.onDirectoryDelete(directory);
    }

    @Override
    public void onFileDelete(File file) {
        super.onFileDelete(file);
    }

    // ......省略其他

}

• 编写monitor

public interface IFileMonitor {
    void startMonitor();
    void stopMonitor();

    void setListener(FileListener listener);
}

public class FileMonitor implements IFileMonitor {
    private FileAlterationMonitor monitor;
    private FileAlterationObserver observer;

    private FileListener listener;

    // seconds
    private long time;
    private String path;

    public FileMonitor(int seconds, String path){
        this.time = seconds;
        this.path = path;
    }

    public void setListener(FileListener listener){
        this.listener = listener;
    }

    public void startMonitor(){
        observer = new FileAlterationObserver(path);
        observer.addListener(listener);

        monitor = new FileAlterationMonitor(TimeUnit.SECONDS.toMillis(time));
        monitor.addObserver(observer);

        try {
            monitor.start();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public void stopMonitor(){
        try {
            monitor.stop();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

• 其他
  其中关闭monitor需要调用stop方法, 查看源码如下。
  默认使用interval设置join时间，并传递中断信号。
  使用变量running控制线程退出。

  public synchronized void stop() throws Exception {
        this.stop(this.interval);
    }

    public synchronized void stop(long stopInterval) throws Exception {
        if(!this.running) {
            throw new IllegalStateException("Monitor is not running");
        } else {
            this.running = false;

            try {
                this.thread.join(stopInterval);
            } catch (InterruptedException var5) {
                Thread.currentThread().interrupt();
            }

            Iterator i$ = this.observers.iterator();

            while(i$.hasNext()) {
                FileAlterationObserver observer = (FileAlterationObserver)i$.next();
                observer.destroy();
            }

        }
    }

• 其他注意点
  在同一个monitor周期中，如果快速的删除和恢复同样的文件(属性没有任何变化)，并不会触发事件调用。