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jdk 8-future 异步处理-轮询isDone判断完成-springBoot示例
Future接口用于获取异步计算的结果，可通过get()获取结果、cancel()取消、isDone()判断是否完成等操作。
V get()： 获取结果，若无结果会阻塞至异步计算完成
V get(long timeOut, TimeUnit unit)：获取结果，超时返回null
boolean isDone()：执行结束（完成/取消/异常）返回true
boolean isCancelled()：任务完成前被取消返回true
boolean cancel(boolean mayInterruptRunning)：取消任务，未开始或已完成返回false，参数表示是否中断执行中的线程
java的Timer类来进行定时调用，schedule(TimerTask task, long delay)调度一个task，经过delay(ms)后开始进行调度，仅仅调度一次参考
在 Java Future 上使用带有 isDone 和 Cancel 的轮询而不是阻塞 get
Future的isDone()方法结果为true代表了什么？
java Timer（定时调用、实现固定时间执行）
Java之Future（cancel，iSDone）
Java多线程任务超时结束的5种实现方法操作
pom
<parent> <artifactId>spring-boot-starter-parentartifactId> <groupId>org.springframework.bootgroupId> <version>2.3.1.RELEASEversion> <relativePath/> parent> <properties> <maven.compiler.source>8maven.compiler.source> <maven.compiler.target>8maven.compiler.target> <java.version>1.8java.version> <project.build.sourceEncoding>UTF-8project.build.sourceEncoding> <project.reporting.outputEncoding>UTF-8project.reporting.outputEncoding> <skipTests>trueskipTests> <spring-boot.version>2.3.1.RELEASEspring-boot.version> properties> <dependencies> <dependency> <groupId>org.springframework.bootgroupId> <artifactId>spring-boot-starter-webartifactId> dependency> <dependency> <groupId>org.springframework.bootgroupId> <artifactId>spring-boot-starterartifactId> dependency> dependencies>- 1
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java测试代码
package ***.cfg; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.core.annotation.Order; import org.springframework.core.task.AsyncTaskExecutor; import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor; import javax.annotation.PostConstruct; import java.util.*; import java.util.concurrent.Future; import java.util.concurrent.ThreadLocalRandom; import java.util.concurrent.ThreadPoolExecutor; import java.util.concurrent.TimeUnit; /** * ExecutorPoolConfig 类说明: * * @author z.y * @version v1.0 * @date 2022/7/27 */ @Order @Configuration public class ExecutorPoolConfig { private static final Logger log = LoggerFactory.getLogger(ExecutorPoolConfig.class); @Bean ("taskNotifyThread") public AsyncTaskExecutor taskNotifyThread(){ ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor(); executor.setCorePoolSize(1); executor.setMaxPoolSize(10); executor.setKeepAliveSeconds(60); executor.setQueueCapacity(1); executor.setThreadNamePrefix("TASK-"); executor.setRejectedExecutionHandler(new ThreadPoolExecutor.DiscardPolicy()); executor.initialize(); log.info("线程池-初始化"); return executor; } public void testPool(int size){ try { size = Math.max(4,size); log.info("开始测试 线程池，数量 {}",size); AsyncTaskExecutor executor = taskNotifyThread(); Map<String, Future<Boolean>> map = new HashMap<>(size); for (int i = 0; i < size; i++) { int index = i; map.put("T-"+index,executor.submit(() -> testOne(index))); } log.info("任务 已提交 线程池，数量 {}",size); Set<String> keySet = map.keySet(); List<String> doneList = new ArrayList<>(size); // 方式1 使用 get 阻塞判断否结束-------------- Boolean b; for (String key : keySet) { b = map.get(key).get(); if(null != b){ log.info("get 阻塞判断是否结束,{}",b); doneList.add(key); } } // 方式1 使用 get 阻塞判断是结束-------------- // 方式2 使用 isDone 轮询判断是结束--------------- Future<Boolean> future; while (keySet.size() != doneList.size()){ for (String key : keySet) { // 已结束的子任务 直接跳过 if(doneList.contains(key)){ continue; } future = map.get(key); if(future.isDone()){ doneList.add(key); log.info("子任务已结束,{},{}",key,future.get()); }else{ log.info("子任务未结束-===-{}",key); } } log.info("问了一遍,结束的任务:{},先睡1s",doneList); TimeUnit.SECONDS.sleep(1); } // 方式2 使用 isDone 轮询判断是结束--------------- log.info("都已经处理结束,结束的顺序:{}",doneList); }catch (Exception e){ log.error("任务测试失败",e); } } private Boolean testOne(int index){ try { int i = ThreadLocalRandom.current().nextInt(2,10); log.info("子任务-{}-开始,睡眠:{}",index,i); TimeUnit.SECONDS.sleep(i); log.info("子任务-{}=====结束,睡眠:{}",index,i); return i % 2 == 0; }catch (Exception e){ log.error("子任务测试失败",e); } return false; } @PostConstruct public void init(){ log.info("配置类初始化完成"); new Timer().schedule(new TimerTask() { @Override public void run() { log.info("线程池开始处理"); testPool(6); } }, 2000); } }- 1
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日志
方式2-轮询处理
2022-07-28 08:54:55.722 INFO 17952 --- [ main] ***.cfg.ExecutorPoolConfig : 线程池-初始化 2022-07-28 08:54:55.723 INFO 17952 --- [ main] o.s.s.concurrent.ThreadPoolTaskExecutor : Initializing ExecutorService 'taskNotifyThread' 2022-07-28 08:54:55.992 INFO 17952 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 9980 (http) with context path '/runner-demo' 2022-07-28 08:54:56.002 INFO 17952 --- [ main] ***.RunnerSpringDemoApplication : Started RunnerSpringDemoApplication in 2.32 seconds (JVM running for 4.784) 2022-07-28 08:54:56.004 INFO 17952 --- [ main] ***.RunnerSpringDemoApplication : http://127.0.0.1:9980/runner-demo/ 2022-07-28 08:54:57.714 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 线程池开始处理 2022-07-28 08:54:57.714 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 开始测试 线程池，数量 6 2022-07-28 08:54:57.715 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 任务 已提交 线程池，数量 6 2022-07-28 08:54:57.716 INFO 17952 --- [ TASK-4] ***.cfg.ExecutorPoolConfig : 子任务-4-开始,睡眠:2 2022-07-28 08:54:57.716 INFO 17952 --- [ TASK-3] ***.cfg.ExecutorPoolConfig : 子任务-3-开始,睡眠:3 2022-07-28 08:54:57.716 INFO 17952 --- [ TASK-5] ***.cfg.ExecutorPoolConfig : 子任务-5-开始,睡眠:9 2022-07-28 08:54:57.716 INFO 17952 --- [ TASK-1] ***.cfg.ExecutorPoolConfig : 子任务-0-开始,睡眠:2 2022-07-28 08:54:57.716 INFO 17952 --- [ TASK-2] ***.cfg.ExecutorPoolConfig : 子任务-2-开始,睡眠:4 2022-07-28 08:54:57.716 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务未结束-===-T-2 2022-07-28 08:54:57.716 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务未结束-===-T-1 2022-07-28 08:54:57.716 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务未结束-===-T-4 2022-07-28 08:54:57.716 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务未结束-===-T-3 2022-07-28 08:54:57.717 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务未结束-===-T-5 2022-07-28 08:54:57.717 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务未结束-===-T-0 2022-07-28 08:54:57.717 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 问了一遍,结束的任务:[],先睡1s 2022-07-28 08:54:58.717 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务未结束-===-T-2 2022-07-28 08:54:58.717 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务未结束-===-T-1 2022-07-28 08:54:58.717 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务未结束-===-T-4 2022-07-28 08:54:58.717 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务未结束-===-T-3 2022-07-28 08:54:58.717 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务未结束-===-T-5 2022-07-28 08:54:58.717 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务未结束-===-T-0 2022-07-28 08:54:58.717 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 问了一遍,结束的任务:[],先睡1s 2022-07-28 08:54:59.717 INFO 17952 --- [ TASK-4] ***.cfg.ExecutorPoolConfig : 子任务-4=====结束,睡眠:2 2022-07-28 08:54:59.717 INFO 17952 --- [ TASK-1] ***.cfg.ExecutorPoolConfig : 子任务-0=====结束,睡眠:2 2022-07-28 08:54:59.717 INFO 17952 --- [ TASK-4] ***.cfg.ExecutorPoolConfig : 子任务-1-开始,睡眠:4 2022-07-28 08:54:59.718 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务未结束-===-T-2 2022-07-28 08:54:59.718 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务未结束-===-T-1 2022-07-28 08:54:59.718 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务已结束,T-4,true 2022-07-28 08:54:59.718 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务未结束-===-T-3 2022-07-28 08:54:59.718 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务未结束-===-T-5 2022-07-28 08:54:59.718 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务已结束,T-0,true 2022-07-28 08:54:59.718 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 问了一遍,结束的任务:[T-4, T-0],先睡1s 2022-07-28 08:55:00.717 INFO 17952 --- [ TASK-3] ***.cfg.ExecutorPoolConfig : 子任务-3=====结束,睡眠:3 2022-07-28 08:55:00.719 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务未结束-===-T-2 2022-07-28 08:55:00.719 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务未结束-===-T-1 2022-07-28 08:55:00.719 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务已结束,T-3,false 2022-07-28 08:55:00.719 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务未结束-===-T-5 2022-07-28 08:55:00.719 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 问了一遍,结束的任务:[T-4, T-0, T-3],先睡1s 2022-07-28 08:55:01.716 INFO 17952 --- [ TASK-2] ***.cfg.ExecutorPoolConfig : 子任务-2=====结束,睡眠:4 2022-07-28 08:55:01.720 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务已结束,T-2,true 2022-07-28 08:55:01.720 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务未结束-===-T-1 2022-07-28 08:55:01.720 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务未结束-===-T-5 2022-07-28 08:55:01.720 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 问了一遍,结束的任务:[T-4, T-0, T-3, T-2],先睡1s 2022-07-28 08:55:02.721 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务未结束-===-T-1 2022-07-28 08:55:02.721 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务未结束-===-T-5 2022-07-28 08:55:02.721 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 问了一遍,结束的任务:[T-4, T-0, T-3, T-2],先睡1s 2022-07-28 08:55:03.718 INFO 17952 --- [ TASK-4] ***.cfg.ExecutorPoolConfig : 子任务-1=====结束,睡眠:4 2022-07-28 08:55:03.721 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务已结束,T-1,true 2022-07-28 08:55:03.721 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务未结束-===-T-5 2022-07-28 08:55:03.721 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 问了一遍,结束的任务:[T-4, T-0, T-3, T-2, T-1],先睡1s 2022-07-28 08:55:04.722 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务未结束-===-T-5 2022-07-28 08:55:04.722 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 问了一遍,结束的任务:[T-4, T-0, T-3, T-2, T-1],先睡1s 2022-07-28 08:55:05.723 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务未结束-===-T-5 2022-07-28 08:55:05.723 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 问了一遍,结束的任务:[T-4, T-0, T-3, T-2, T-1],先睡1s 2022-07-28 08:55:06.716 INFO 17952 --- [ TASK-5] ***.cfg.ExecutorPoolConfig : 子任务-5=====结束,睡眠:9 2022-07-28 08:55:06.723 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 子任务已结束,T-5,false 2022-07-28 08:55:06.723 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 问了一遍,结束的任务:[T-4, T-0, T-3, T-2, T-1, T-5],先睡1s 2022-07-28 08:55:07.724 INFO 17952 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 都已经处理结束,结束的顺序:[T-4, T-0, T-3, T-2, T-1, T-5]- 1
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方式1-阻塞获取
--2022-07-29 10:19:25.436 - INFO 19288 --- [ main] ***.cfg.ExecutorPoolConfig : 线程池-初始化 --2022-07-29 10:19:25.438 - INFO 19288 --- [ main] o.s.s.concurrent.ThreadPoolTaskExecutor : Initializing ExecutorService 'taskNotifyThread' --2022-07-29 10:19:25.819 - INFO 19288 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 9980 (http) with context path '/runner-demo' --2022-07-29 10:19:25.831 - INFO 19288 --- [ main] ***.RunnerSpringDemoApplication : Started RunnerSpringDemoApplication in 3.103 seconds (JVM running for 6.078) --2022-07-29 10:19:25.834 - INFO 19288 --- [ main] ***.RunnerSpringDemoApplication : http://127.0.0.1:9980/runner-demo/ --2022-07-29 10:19:27.424 - INFO 19288 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 线程池开始处理 --2022-07-29 10:19:27.424 - INFO 19288 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 开始测试 线程池，数量 6 --2022-07-29 10:19:27.427 - INFO 19288 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 任务 已提交 线程池，数量 6 --2022-07-29 10:19:27.427 - INFO 19288 --- [ TASK-5] ***.cfg.ExecutorPoolConfig : 子任务-5-开始,睡眠:6 --2022-07-29 10:19:27.427 - INFO 19288 --- [ TASK-2] ***.cfg.ExecutorPoolConfig : 子任务-2-开始,睡眠:2 --2022-07-29 10:19:27.427 - INFO 19288 --- [ TASK-1] ***.cfg.ExecutorPoolConfig : 子任务-0-开始,睡眠:7 --2022-07-29 10:19:27.427 - INFO 19288 --- [ TASK-4] ***.cfg.ExecutorPoolConfig : 子任务-4-开始,睡眠:2 --2022-07-29 10:19:27.427 - INFO 19288 --- [ TASK-3] ***.cfg.ExecutorPoolConfig : 子任务-3-开始,睡眠:7 --2022-07-29 10:19:29.429 - INFO 19288 --- [ TASK-2] ***.cfg.ExecutorPoolConfig : 子任务-2=====结束,睡眠:2 --2022-07-29 10:19:29.429 - INFO 19288 --- [ TASK-4] ***.cfg.ExecutorPoolConfig : 子任务-4=====结束,睡眠:2 --2022-07-29 10:19:29.429 - INFO 19288 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : get 阻塞判断是否结束,true --2022-07-29 10:19:29.429 - INFO 19288 --- [ TASK-4] ***.cfg.ExecutorPoolConfig : 子任务-1-开始,睡眠:3 --2022-07-29 10:19:32.430 - INFO 19288 --- [ TASK-4] ***.cfg.ExecutorPoolConfig : 子任务-1=====结束,睡眠:3 --2022-07-29 10:19:32.430 - INFO 19288 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : get 阻塞判断是否结束,false --2022-07-29 10:19:32.431 - INFO 19288 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : get 阻塞判断是否结束,true --2022-07-29 10:19:33.429 - INFO 19288 --- [ TASK-5] ***.cfg.ExecutorPoolConfig : 子任务-5=====结束,睡眠:6 --2022-07-29 10:19:34.429 - INFO 19288 --- [ TASK-1] ***.cfg.ExecutorPoolConfig : 子任务-0=====结束,睡眠:7 --2022-07-29 10:19:34.429 - INFO 19288 --- [ TASK-3] ***.cfg.ExecutorPoolConfig : 子任务-3=====结束,睡眠:7 --2022-07-29 10:19:34.429 - INFO 19288 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : get 阻塞判断是否结束,false --2022-07-29 10:19:34.429 - INFO 19288 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : get 阻塞判断是否结束,true --2022-07-29 10:19:34.429 - INFO 19288 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : get 阻塞判断是否结束,false --2022-07-29 10:19:34.429 - INFO 19288 --- [ Timer-0] ***.cfg.ExecutorPoolConfig : 都已经处理结束,结束的顺序:[T-2, T-1, T-4, T-3, T-5, T-0] -- 1
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结束
get阻塞方式，任务不是最早结束的就能得到结果值，是按照自定义key的 顺序获取结果。
isDone轮询方式，任务是在主线程循环判断，结果顺序是和任务耗时有关，代码较多。
个人见解，如有问题请指出。 -
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- 原文地址：https://blog.csdn.net/privateobject/article/details/126049344
