接上一个问题(http://coding.imooc.com/learn/questiondetail/71817.html), 我的测试代码及现象如下:

public static void main(String[] args) {
		ThreadFactory threadFactory = new ThreadFactoryBuilder().setNameFormat("doing-%d").build();
		ThreadPoolExecutor executor = new ThreadPoolExecutor(100, 100, 0L, TimeUnit.MINUTES,
				new LinkedBlockingQueue<Runnable>(1), threadFactory, new ThreadPoolExecutor.AbortPolicy());
		final FileService fileService = new FileService();
		for (int i = 0; i < 100; i++) {
			executor.execute(new Runnable() {
				@Override
				public void run() {
					fileService.write("20180802");
				}
			});
		}
		executor.shutdown();
}

public static class FileService {
		private static final String TEST_DIR = "/test4mut";
		private static final String FLAG = "/_DOING";
		public void write(String date){
			if(check(date)){
				System.out.println(Thread.currentThread().getName() + " doing....");
			}else{
				//System.out.println("---------");
			}
		}
		public boolean check(String date){

			String dir = TEST_DIR+date;
			File flag = new File(dir+FLAG);

			if(flag.exists()){
				return false;
			}else{
				try {
					flag.createNewFile();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			return true;
		}
 }	

运行结果:

doing-0 doing....
doing-1 doing....

想问下老师,我上面那个同步应该怎么编写