Java多线程的实现方式

继承Thread ，实现Runnable， 实现Callable

callable有返回值

Thread

public class Test1_Thread {
  public static void main(String[] args) {
      new Test1_thread().start();
      System.out.println("任务1已启动  ");

      new Test1_thread().start();
      System.out.println("任务2已启动  ");
  }

  static class Test1_thread extends Thread {
    @Override
    public void run() {
      for (int j = 0; j < 5; j++) {
        Autil.w1s(1);
        Autil.printCurrent(j);
      }
    }
  }
}

Runnable

public class Test2_Runnable {
    public static void main(String[] args) {
        new Thread(new Test2_myRunnable()).start();
        System.out.println("任务1已启动  ");

        new Thread(new Test2_myRunnable()).start();
        System.out.println("任务2已启动  ");
    }

    static class Test2_myRunnable implements Runnable {
        @Override
        public void run() {
            for (int j = 0; j < 5; j++) {
                Autil.w1s(1);
                Autil.printCurrent(j);
            }
        }
    }
}

Callable

public class Test3_Callable {

    /**
     * 需要将任务交给线程池
     */
    public static void main(String[] args) throws Exception {
        // 1. 创建线程池
        ExecutorService pool = Executors.newCachedThreadPool();
        // 2. 向线程池提交任务
        Future<Integer> future1 = pool.submit(new Test3_myCallable());
        System.out.println("任务1已提交  ");

        // 3. 获取线程的返回值
        System.out.println("------------------开始查询所有子线程的返回值   ");
        // --3.1 获取方式一： 阻塞方式等待返回值
        // Integer j = future1.get();

        int flag = 10;

        // --3.2 获取方式二，不停的询问线程任务是否执行完成了
        while (10 == flag) {
            if (future1.isDone()) {
                flag = 6;
                System.out.println(" ");
                System.out.println(flag + "返回值为  " + future1.get());
            } else {
                System.out.print("任务尚未完成 ");
                Thread.sleep(50);
            }
        }

        // 线程池运行结束后关闭
        pool.shutdown();
        System.out.println("运行结束  " + Thread.activeCount());
    }

    static class Test3_myCallable implements Callable<Integer> {

        @Override
        public Integer call() throws Exception {
            Autil.w1s(1);
            Autil.printCurrentTimes(3);
            return 33;
        }
    }

}

jdk1.7: fork_join

import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.ForkJoinTask;
import java.util.concurrent.RecursiveTask;

/**
 * 当工作量大时，对任务进行水平拆分。
 */
public class Test9_fork {
    public static void main(String[] args) throws Exception {
        ForkJoinPool fjp = new ForkJoinPool();

        Sum sum = new Sum(1, 1_0);
        ForkJoinTask<Long> task = fjp.submit(sum);
        System.out.println("提交完毕");

        Long result = task.get();
        System.out.println("输出结果" + result);

    }

    static class Sum extends RecursiveTask<Long> {
        private final long from;
        private final long to;

        Sum(long from, long to) {
            this.from = from;
            this.to = to;
        }

        static boolean tooBiger(long from, long to) {
            return (to - from) > 3 ? true : false;
        }

        static long sum(long from, long to) {
            long sum = 0;
            for (; from < to; from++) {
                sum += from;
            }
            return sum;
        }

        @Override
        protected Long compute() {
            if (tooBiger(from, to)) {
                // 任务量太大
                long middle = (to + from) / 2;
                Sum sum1 = new Sum(from, middle);
                Sum sum2 = new Sum(middle, to);

                sum1.fork();
                sum2.fork();
                long sum = 0;
                sum = sum1.join() + sum2.join();

                System.out.println(sum + "  " + from + " > " + middle + " > " + to);
                return sum;
            } else {
                long sum = sum(from, to);
                System.out.println(sum + " == " + from + " > " + to);
                return sum;
            }

        }

    }
}

代码地址 ： https://github.com/fluffywar/Demo/tree/master/concurrency/test1_thread/src/test/java/com/example/demo1