Java中Fork/Join框架

分割任务，然后把子任务的结果再合并起来。分治的思想。

import java.util.concurrent.ForkJoinPool;import java.util.concurrent.Future;import java.util.concurrent.RecursiveTask;public class CountTask extends RecursiveTask<Integer>{/** *  */private static final long serialVersionUID = 1L;private static final int THRESHOLD = 1000;private int start;private int end;public CountTask(int start, int end) {this.start = start;this.end = end;}@Overrideprotected Integer compute() {int sum = 0;boolean canCompute = (end - start) <= THRESHOLD;if (canCompute) {for (int i = start; i <= end; i++)sum += i;} else {//如果任务大于阀值，就分裂成两个子任务计算int mid = (start + end) / 2;CountTask leftTask = new CountTask(start, mid);CountTask rightTask = new CountTask(mid+1, end);//执行子任务leftTask.fork();rightTask.fork();//等待子任务执行完，并得到结果int leftResult = (int)leftTask.join();int rightResult = (int)rightTask.join();sum = leftResult + rightResult;}return sum;}public static void main(String[] args) {ForkJoinPool forkJoinPool = new ForkJoinPool();        //生成一个计算资格，负责计算1+2+3+4          CountTask task = new CountTask(1, 100000000);         Future<Integer> result = forkJoinPool.submit(task);        try {        long start = System.currentTimeMillis();        System.out.println(result.get());        System.out.println("所用时长： " + (System.currentTimeMillis() - start) + "毫秒");} catch (Exception e) {}}}

下面是用单线程的跑的时间，一个for跑的。