Java7之forkjoin简介_动力节点Java学院整理

public class MyForkJoinTask extends ForkJoinTask {
 
 /**
  *
  */
 private static final long serialVersionUID = 1L;
 private V value;
 private boolean success = false;
 @Override
 public V getRawResult() {
  return value;
 }
 @Override
 protected void setRawResult(V value) {
  this.value = value;
 }
 @Override
 protected boolean exec() {
  System.out.println("exec");
  return this.success;
 }
 public boolean isSuccess() {
  return success;
 }
 public void setSuccess(boolean isSuccess) {
  this.success = isSuccess;
 }
}

 @Test
 public void testForkJoinInvoke() throws InterruptedException, ExecutionException {
  ForkJoinPool forkJoinPool = new ForkJoinPool();
  MyForkJoinTask task = new MyForkJoinTask();
  task.setSuccess(true);
  task.setRawResult("test");
  String invokeResult = forkJoinPool.invoke(task);
  assertEquals(invokeResult, "test");
 }
 @Test
 public void testForkJoinInvoke2() throws InterruptedException, ExecutionException {
  final ForkJoinPool forkJoinPool = new ForkJoinPool();
  final MyForkJoinTask task = new MyForkJoinTask();
  new Thread(new Runnable() {
   public void run() {
    try {
     Thread.sleep(1000);
    } catch (InterruptedException e) {
    }
    task.complete("test");
   }
  }).start();
  // exec()返回值是false，此处阻塞，直到另一个线程调用了task.complete(...)
  String result = forkJoinPool.invoke(task);
  System.out.println(result);
 }
 @Test
 public void testForkJoinSubmit() throws InterruptedException, ExecutionException {
  final ForkJoinPool forkJoinPool = new ForkJoinPool();
  final MyForkJoinTask task = new MyForkJoinTask();
  task.setSuccess(true); // 是否在此任务运行完毕后结束阻塞
  ForkJoinTask result = forkJoinPool.submit(task);
  result.get(); // 如果exec()返回值是false，在此处会阻塞，直到调用complete
 }

@Test
 public void testForkJoinSubmit() throws InterruptedException, ExecutionException {
  final ForkJoinPool forkJoinPool = new ForkJoinPool();
  final MyForkJoinTask task = new MyForkJoinTask();
  task.setSuccess(true); // 是否在此任务运行完毕后结束阻塞
  ForkJoinTask result = forkJoinPool.submit(task);
  result.get(); // 如果exec()返回值是false，在此处会阻塞，直到调用complete
 }
 @Test
 public void testForkJoinSubmit2() throws InterruptedException, ExecutionException {
  final ForkJoinPool forkJoinPool = new ForkJoinPool();
  final MyForkJoinTask task = new MyForkJoinTask();
  forkJoinPool.submit(task);
  Thread.sleep(1000);
 }
 @Test
 public void testForkJoinSubmit3() throws InterruptedException, ExecutionException {
  final ForkJoinPool forkJoinPool = new ForkJoinPool();
  final MyForkJoinTask task = new MyForkJoinTask();
  new Thread(new Runnable() {
   public void run() {
    try {
     Thread.sleep(1000);
    } catch (InterruptedException e) {
    }
    task.complete("test");
   }
  }).start();
  ForkJoinTask result = forkJoinPool.submit(task);
  // exec()返回值是false，此处阻塞，直到另一个线程调用了task.complete(...)
  result.get();
  Thread.sleep(1000);
 }

 @Test
 public void testForkJoinExecute() throws InterruptedException, ExecutionException {
  ForkJoinPool forkJoinPool = new ForkJoinPool();
  MyForkJoinTask task = new MyForkJoinTask();
  forkJoinPool.execute(task); // 异步执行，无视task.exec()返回值。
 }

import java.util.Random;
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.RecursiveTask;
public class MaximumFinder extends RecursiveTask<Integer> {
 private static final int SEQUENTIAL_THRESHOLD = 5;
 private final int[] data;
 private final int start;
 private final int end;
 public MaximumFinder(int[] data, int start, int end) {
 this.data = data;
 this.start = start;
 this.end = end;
 }
 public MaximumFinder(int[] data) {
 this(data, 0, data.length);
 }
 @Override
 protected Integer compute() {
 final int length = end - start;
 if (length < SEQUENTIAL_THRESHOLD) {
  return computeDirectly();
 }
 final int split = length / 2;
 final MaximumFinder left = new MaximumFinder(data, start, start + split);
 left.fork();
 final MaximumFinder right = new MaximumFinder(data, start + split, end);
 return Math.max(right.compute(), left.join());
 }
 private Integer computeDirectly() {
 System.out.println(Thread.currentThread() + ' computing: ' + start
      + ' to ' + end);
 int max = Integer.MIN_VALUE;
 for (int i = start; i < end; i++) {
  if (data[i] > max) {
  max = data[i];
  }
 }
 return max;
 }
 public static void main(String[] args) {
 // create a random data set
 final int[] data = new int[1000];
 final Random random = new Random();
 for (int i = 0; i < data.length; i++) {
  data[i] = random.nextInt(100);
 }
 // submit the task to the pool
 final ForkJoinPool pool = new ForkJoinPool(4);
 final MaximumFinder finder = new MaximumFinder(data);
 System.out.println(pool.invoke(finder));
 }
}