一、创建线程
@Test public void test0() throws Exception { System.out.println("main函数开始执行"); Thread thread=new Thread(new Runnable() { @Override public void run() { System.out.println("===task start==="); try { Thread.sleep(5000); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println("===task finish==="); } }); thread.start(); System.out.println("main函数执行结束"); }
二、Future
jdk8之前的实现方式,在JUC下增加了Future,从字面意思理解就是未来的意思,但使用起来却着实有点鸡肋,并不能实现真正意义上的异步,获取结果时需要阻塞线程,或者不断轮询。
@Test public void test1() throws Exception { System.out.println("main函数开始执行"); ExecutorService executor = Executors.newFixedThreadPool(1); Future<Integer> future = executor.submit(new Callable<Integer>() { @Override public Integer call() throws Exception { System.out.println("===task start==="); Thread.sleep(5000); System.out.println("===task finish==="); return 3; } }); //这里需要返回值时会阻塞主线程,如果不需要返回值使用是OK的。倒也还能接收 //Integer result=future.get(); System.out.println("main函数执行结束"); System.in.read(); }
三、CompletableFuture
使用原生的CompletableFuture实现异步操作,加上对lambda的支持,可以说实现异步任务已经发挥到了极致。
@Test public void test2() throws Exception { System.out.println("main函数开始执行"); ExecutorService executor = Executors.newFixedThreadPool(2); CompletableFuture<Integer> future = CompletableFuture.supplyAsync(new Supplier<Integer>() { @Override public Integer get() { System.out.println("===task start==="); try { Thread.sleep(5000); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println("===task finish==="); return 3; } }, executor); future.thenAccept(e -> System.out.println(e)); System.out.println("main函数执行结束"); }
四、Spring的Async注解
使用spring实现异步需要开启注解,可以使用xml方式或者java config的方式。
xml方式:
<task:annotation-driven executor="executor" /> <task:executor id="executor" pool-size="2" 线程池的大小 queue-capacity="100" 排队队列长度 keep-alive="120" 线程保活时间(单位秒) rejection-policy="CALLER_RUNS" 对拒绝的任务处理策略 />
java方式:
@EnableAsync public class MyConfig { @Bean public TaskExecutor executor(){ ThreadPoolTaskExecutor executor=new ThreadPoolTaskExecutor(); executor.setCorePoolSize(10); //核心线程数 executor.setMaxPoolSize(20); //最大线程数 executor.setQueueCapacity(1000); //队列大小 executor.setKeepAliveSeconds(300); //线程最大空闲时间 executor.setThreadNamePrefix("fsx-Executor-"); //指定用于新创建的线程名称的前缀。 executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy()); return executor; } }
(1)@Async
@Test public void test3() throws Exception { System.out.println("main函数开始执行"); myService.longtime(); System.out.println("main函数执行结束"); } @Async public void longtime() { System.out.println("我在执行一项耗时任务"); try { Thread.sleep(5000); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println("完成"); }
(2)AsyncResult
如果需要返回值,耗时方法返回值用AsyncResult包装。
@Test public void test4() throws Exception { System.out.println("main函数开始执行"); Future<Integer> future=myService.longtime2(); System.out.println("main函数执行结束"); System.out.println("异步执行结果:"+future.get()); } @Async public Future<Integer> longtime2() { System.out.println("我在执行一项耗时任务"); try { Thread.sleep(8000); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println("完成"); return new AsyncResult<>(3); }
来源:https://www.cnblogs.com/sword-successful/p/11181714.html