网站开发过程中出现的问题,教育网站建设的素材,什么是网站app建设,做淘宝链接模板网站FutureTask是一种可以取消的异步的计算任务。它的计算是通过Callable实现的#xff0c;它等价于可以携带结果的Runnable#xff0c;并且有三个状态#xff1a;等待、运行和完成。完成包括所有计算以任意的方式结束#xff0c;包括正常结束、取消和异常。Future有个get方法而…FutureTask是一种可以取消的异步的计算任务。它的计算是通过Callable实现的它等价于可以携带结果的Runnable并且有三个状态等待、运行和完成。完成包括所有计算以任意的方式结束包括正常结束、取消和异常。Future有个get方法而获取结果只有在计算完成时获取否则会一直阻塞直到任务转入完成状态然后会返回结果或者抛出异常。FutureTask有下面几个重要的方法1.get()阻塞一直等待执行完成拿到结果2.get(int timeout, TimeUnit timeUnit)阻塞一直等待执行完成拿到结果如果在超时时间内没有拿到抛出异常3.isCancelled()是否被取消4.isDone()是否已经完成5.cancel(boolean mayInterruptIfRunning)试图取消正在执行的任务用ThreadPoolExecutor和FutureTask实现可取消任务线程池private Map tasks new HashMap();// 构造一个线程private ThreadPoolExecutor executor new ThreadPoolExecutor(1, 1, 0L, TimeUnit.MILLISECONDS, newLinkedBlockingQueue());/*** param tasksList*/public void addTaskList(List tasksList) {for (Callable t : tasksList) {FutureTask futureTask new FutureTask(t);executor.execute(futureTask);String key Long.toHexString(System.nanoTime());tasks.put(key, futureTask);}}/*** param task* return*/public String addTask(Callable task) {FutureTask futureTask new FutureTask(task);executor.execute(futureTask);String key Long.toHexString(System.nanoTime());tasks.put(key, futureTask);return key;}/*** param task* return*/public String addDBTask(Callable task) {FutureTask futureTask new FutureTask(task) {public boolean cancel(boolean mayInterruptIfRunning) {System.out.println(Roll Back and Closs Session);return super.cancel(mayInterruptIfRunning);}};executor.execute(futureTask);String key Long.toHexString(System.nanoTime());tasks.put(key, futureTask);return key;}/*** param key* return*/public boolean taskIsDone(String key) {FutureTask futureTask tasks.get(key);if (futureTask ! null) {return futureTask.isDone();}return false;}/*** param key* return*/public boolean taskIsCancelled(String key) {FutureTask futureTask tasks.get(key);if (futureTask ! null) {return futureTask.isCancelled();}return false;}/*** param key* return*/public String getTaskResult(String key) {FutureTask futureTask tasks.get(key);if (futureTask.isDone()) {try {String result futureTask.get();tasks.remove(key);return result;} catch (InterruptedException e) {e.printStackTrace();return null;} catch (ExecutionException e) {e.printStackTrace();return null;}} else {return null;}}/*** param task* return*/public String addTaskAndWaitResult(Callable task) {FutureTask futureTask new FutureTask(task);executor.execute(futureTask);String key Long.toHexString(System.nanoTime());tasks.put(key, futureTask);try {return futureTask.get();} catch (InterruptedException e) {e.printStackTrace();return null;} catch (ExecutionException e) {e.printStackTrace();return null;}}/****/public void removeAllTask() {for (String key : tasks.keySet()) {executor.remove((Runnable) tasks.get(key));tasks.remove(key);}}/*** param key*/public void removeQueryTask(String key) {executor.remove((Runnable) tasks.get(key));}/*** param key*/public void removeTask(String key) {tasks.remove(key);}/****/public void clearTaskList() {tasks.clear();}public synchronized void stop(){try {executor.shutdownNow();executor.awaitTermination(1L, TimeUnit.MILLISECONDS);} catch (InterruptedException e) {e.printStackTrace();} finally {executor null;tasks.clear();tasks null;}}/*** param key*/public void cancelTask(String key) {FutureTask futureTask tasks.get(key);if (futureTask ! null) {if (!futureTask.isDone()) {futureTask.cancel(true);}}}public void purgeCancelTask() {executor.purge();executor.getQueue();}/*** param args*/public static void main(String[] args) {ImageSearchThreadPool exec new ImageSearchThreadPool();ArrayList keyList new ArrayList();ArrayList removeKeyList new ArrayList();ArrayList cancelKeyList new ArrayList();for (int i 0; i // 产生一个任务并将其加入到线程池String task task (i 1);System.out.println(put task);keyList.add(exec.addDBTask(new DBTask(task)));}try {Thread.sleep(1L);} catch (InterruptedException e) {e.printStackTrace();}for (int i 0; i if (exec.taskIsDone(keyList.get(i))) {System.out.println(exec.getTaskResult(keyList.get(i)));exec.removeTask(keyList.get(i));removeKeyList.add(keyList.get(i));} else {exec.cancelTask(keyList.get(i));System.out.println(Cancel task: (i 1));exec.removeTask(keyList.get(i));cancelKeyList.add(keyList.get(i));}}exec.purgeCancelTask();exec.stop();try {Thread.sleep(6000L);} catch (InterruptedException e) {e.printStackTrace();}for (String key : cancelKeyList) {if (exec.taskIsCancelled(key)) {System.out.println(Cancel: key);}}for (int i 0; i keyList.get(i);}}
