线程的并发工具类

1.分而治之 fork join

标准使用范畴：

/**
 * 统计集合数据的和
 */
public class ForkJoinTest1 {
    private static class SumTest extends RecursiveTask<Integer> {
        //阀值
        private final static Integer THRESHOLD = MakeArray.ARRAY_LENGTH/10;
        private int [] arry; // 处理的数据
        private int start;//起点
        private int end;//终点

        public SumTest(int[] arry, int start, int end) {
            this.arry = arry;
            this.start = start;
            this.end = end;
        }

        @Override
        protected Integer compute() {
            if (end - start < THRESHOLD) {
                int sum = 0;
                for (int i= start;i<end;i++) {
                    sum += arry[i];
                }
                return sum;
            }else {

                int mid = (end + start)/2;
                SumTest left = new SumTest(arry,start,mid);
                SumTest right = new SumTest(arry,mid + 1,end);
                invokeAll(left,right);
                return left.join() + right.join();
            }
        }
    }

    public static void main(String[] args) {
        ForkJoinPool pool = new ForkJoinPool();
        int [] src = MakeArray.makeArray(); //获取随机数组
        SumTest sumTest = new SumTest(src,0,src.length - 1);
        pool.invoke(sumTest);
        System.out.println(sumTest.join());
    }
}

无返回值

public class ForkJoinTest2 {
    private static class TestTask extends RecursiveAction{

        public TestTask(File path) {
            this.path = path;
        }

        private File path;

        @Override
        protected void compute() {
            List<TestTask> list = new LinkedList();
            File [] file = path.listFiles();
            if (file != null) {
                for (File f: file ) {
                    if (f.isDirectory()) {
                        list.add(new TestTask(f));
                    }else{
                        if (f.getAbsolutePath().endsWith("txt")) {
                            System.out.println(f.getAbsolutePath());
                        }

                    }
                    
                }
                if (list != null) {
                    for (TestTask test:invokeAll(list)) {
                        test.join();//等其他子线程
                    }
                }
            }

        }

        public static void main(String[] args) {
            //pool调度总任务
            ForkJoinPool pool = new ForkJoinPool();
            TestTask testTask = new TestTask(new File("/Volumes/H/Users/huangxu"));
            //异步调用
            pool.execute(testTask);
            System.out.println("Task is Running......");
            try {
                Thread.sleep(1);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            int otherWork = 0;
            for(int i=0;i<100;i++){
                otherWork = otherWork+i;
            }
            System.out.println("Main Thread done sth......,otherWork="+otherWork);
            testTask.join();//阻塞的方法
            System.out.println("Task end");
        }
    }
}

来源：oschina

链接：https://my.oschina.net/u/3900969/blog/3196532

标签

线程阻塞

join