fork/join演示

public class CountTask extends RecursiveTask<Integer> {
    private static final int THRESHHOLD = 2;
    private int start;
    private int end;

    public CountTask(int start, int end) {
        this.start = start;
        this.end = end;
    }

    @Override
    protected Integer compute() {
        System.out.println(start + " - " + end + " begin");
        int sum = 0;
        boolean canCompute = (end - start) <= THRESHHOLD;
        if (canCompute) { // 达到了计算条件，则直接执行
            System.out.println(start + " - " + end + " canCompute");
            for (int i = start; i <= end; i++) {
                sum += i;
            }
        } else { // 不满足计算条件，则分割任务
            int middle = (start + end) / 2;

            CountTask leftTask = new CountTask(start, middle);
            CountTask rightTask = new CountTask(middle + 1, end);

            leftTask.fork(); // 执行子任务
            rightTask.fork(); // 执行子任务
            int leftResult = leftTask.join(); // 等待子任务执行完毕
            int rightResult = rightTask.join(); // 等待子任务执行完毕

            sum = leftResult + rightResult; // 合并子任务的计算结果
        }
        System.out.println(start + " - " + end + " end");
        return sum;
    }

    public static void main(String[] args) throws InterruptedException, ExecutionException {
        ForkJoinPool pool = new ForkJoinPool();
        CountTask task = new CountTask(1, 8);
        Future<Integer> future = pool.submit(task);
        if (task.isCompletedAbnormally()) {
            System.out.println(task.getException());
        } else {
            System.out.println("result: " + future.get());
        }
        pool.shutdown();
    }

}

public class FileSearchTask extends RecursiveAction {
    private final File directory;

    public FileSearchTask(File directory) {
        this.directory = directory;
    }

    @Override
    protected void compute() {
        File[] files = directory.listFiles();
        if (files != null) {
            for (File file : files) {
                if (file.isDirectory()) {
                    // 如果是目录，创建子任务
                    FileSearchTask task = new FileSearchTask(file);
                    task.fork();
                } else {
                    // 处理文件
                    System.out.println(file.getAbsolutePath());
                }
            }
            // 等待所有子任务完成
            invokeAll();
        }
    }

    public static void main(String[] args) {
        ForkJoinPool pool = new ForkJoinPool();
        pool.invoke(new FileSearchTask(new File("F:\\常用软件"))); //执行任务并等待结果
        pool.shutdown();
    }
}