何谓异步?
每次调用都创建一个新的线程去执行, 不会等待上一次调用执行完,再执行下一个请求
SpringBoot项目怎么做
- 在启动类上添加:@EnableAsync 注解
- 项目中添加下面两个类
import java.util.concurrent.ScheduledExecutorService; import java.util.concurrent.ScheduledThreadPoolExecutor; import java.util.concurrent.ThreadPoolExecutor; import com.imooc.miaoshaproject.util.Threads; import org.apache.commons.lang3.concurrent.BasicThreadFactory; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor; /** * 线程池配置 **/ @Configuration public class ThreadPoolConfig { // 核心线程池大小 private int corePoolSize = 50; // 最大可创建的线程数 private int maxPoolSize = 200; // 队列最大长度 private int queueCapacity = 1000; // 线程池维护线程所允许的空闲时间 private int keepAliveSeconds = 300; @Bean(name = "threadPoolTaskExecutor") public ThreadPoolTaskExecutor threadPoolTaskExecutor() { ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor(); executor.setMaxPoolSize(maxPoolSize); executor.setCorePoolSize(corePoolSize); executor.setQueueCapacity(queueCapacity); executor.setKeepAliveSeconds(keepAliveSeconds); // 线程池对拒绝任务(无线程可用)的处理策略 executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy()); return executor; } /** * 执行周期性或定时任务 */ @Bean(name = "scheduledExecutorService") protected ScheduledExecutorService scheduledExecutorService() { return new ScheduledThreadPoolExecutor(corePoolSize, new BasicThreadFactory.Builder().namingPattern("schedule-pool-%d").daemon(true).build()) { @Override protected void afterExecute(Runnable r, Throwable t) { super.afterExecute(r, t); Threads.printException(r, t); } }; } }
import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.util.concurrent.*; /** * 线程相关工具类. * */ public class Threads { private static final Logger logger = LoggerFactory.getLogger(Threads.class); /** * sleep等待,单位为毫秒 */ public static void sleep(long milliseconds) { try { Thread.sleep(milliseconds); } catch (InterruptedException e) { return; } } /** * 停止线程池 * 先使用shutdown, 停止接收新任务并尝试完成所有已存在任务. * 如果超时, 则调用shutdownNow, 取消在workQueue中Pending的任务,并中断所有阻塞函数. * 如果仍人超時,則強制退出. * 另对在shutdown时线程本身被调用中断做了处理. */ public static void shutdownAndAwaitTermination(ExecutorService pool) { if (pool != null && !pool.isShutdown()) { pool.shutdown(); try { if (!pool.awaitTermination(120, TimeUnit.SECONDS)) { pool.shutdownNow(); if (!pool.awaitTermination(120, TimeUnit.SECONDS)) { logger.info("Pool did not terminate"); } } } catch (InterruptedException ie) { pool.shutdownNow(); Thread.currentThread().interrupt(); } } } /** * 打印线程异常信息 */ public static void printException(Runnable r, Throwable t) { if (t == null && r instanceof Future<?>) { try { Future<?> future = (Future<?>) r; if (future.isDone()) { future.get(); } } catch (CancellationException ce) { t = ce; } catch (ExecutionException ee) { t = ee.getCause(); } catch (InterruptedException ie) { Thread.currentThread().interrupt(); } } if (t != null) { logger.error(t.getMessage(), t); } } }
- 在需要异步调用的接口上添加@Async(“threadPoolTaskExecutor”)注解即可
@Async("threadPoolTaskExecutor") @RequestMapping(value = "/test",method = {RequestMethod.GET,RequestMethod.POST}) @ResponseBody public void test() { System.out.println("===test==="); try { Thread.sleep(10000); } catch (InterruptedException e) { e.printStackTrace(); } }