在第1篇中“并发框架基本示例”，提到了Executors和ThreadPool。
其中，还有个“定时调度”的方法，Executors.newScheduledThreadPool(10)。

// 可执行调度命令(定时+周期性)的线程池，拥有固定的线程数// 重复执行，无穷尽public static void scheduledThreadPool() {int initialDelay = 10;int period = 10;Executor executor = Executors.newScheduledThreadPool(10);ScheduledExecutorService scheduler = (ScheduledExecutorService) executor;scheduler.scheduleAtFixedRate(task, initialDelay, period,TimeUnit.SECONDS);}

这段代码，会一直重复执行，是一种常见的场景。

但是，想到一种“只调度N次”的需求，看了下API，没有提供。
就网上搜索“Java 取消线程调度”，找到了1个问答，就研究了下。
代码示例的关键是，使用了线程安全的AtomicInteger和通用同步工具CountDownLatch。

核心逻辑就是，当超过了最大任务数N的时候，取消Future中的任务，countDownLatch中的计数器-1，变为0，“countDownLatch.await()”线程阻塞结束
countDownLatch.countDown();
关于CountDownLatch的进一步介绍，请参考第4篇。

package cn.fansunion.executorframework;import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;//有条件地，取消调度
public class ConditionCancelSchedulerDemo {public static Runnable task = new Runnable() {@Overridepublic void run() {System.out.println("Execute a task");}};// 可执行调度命令(定时+周期性)的线程池，拥有固定的线程数// 重复执行，无穷尽public static void scheduledThreadPool() {int initialDelay = 10;int period = 10;Executor executor = Executors.newScheduledThreadPool(10);ScheduledExecutorService scheduler = (ScheduledExecutorService) executor;scheduler.scheduleAtFixedRate(task, initialDelay, period,TimeUnit.SECONDS);}public static void main(String[] args) throws Exception {scheduledThreadPool();conditionCancelScheduler();}private static void conditionCancelScheduler() throws InterruptedException {final String jobID = "my_job_1";final AtomicInteger count = new AtomicInteger(0);final Map<String, Future> futures = new HashMap<>();// 最多执行10个任务final int maxTaskSize = 10;// CountDownLatch的更多用法，请参考CountDownLatchDemofinal CountDownLatch countDownLatch = new CountDownLatch(1);ScheduledExecutorService scheduler = Executors.newSingleThreadScheduledExecutor();Future future = scheduler.scheduleWithFixedDelay(new Runnable() {@Overridepublic void run() {System.out.println(count.getAndIncrement());// 当调度执行，第maxTaskSize+1个任务的时候，取消Future中的任务。第11个任务if (count.get() > maxTaskSize) {System.out.println("a");Future f = futures.get(jobID);if (f != null) {f.cancel(true);}// countDownLatch中的计数器-1，变为0// “countDownLatch.await()”线程阻塞结束countDownLatch.countDown();}}}, 0, 1, TimeUnit.SECONDS);futures.put(jobID, future);countDownLatch.await();scheduler.shutdown();}
}

更多代码示例：
http://git.oschina.net/fansunion/Concurrent（逐步更新中）

参考资料：
java并发编程-Executor框架
http://www.iteye.com/topic/366591

有条件地终止 ScheduledExecutorService 中运行的定时任务
http://www.oschina.net/question/1158769_119659?sort=time

JDK API 文档