Spring 中的 @Async 和 @Scheduled 理解

@Async

spring-test.xml文件

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<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi= "http://www.w3.org/2001/XMLSchema-instance" xmlns:context= "http://www.springframework.org/schema/context" xmlns:task= "http://www.springframework.org/schema/task" xsi:schemaLocation= "http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task-3.2.xsd"> <task:annotation-driven scheduler="myScheduler" executor="myExecutor"/> <task:executor id="myExecutor" pool-size="20"/> <task:scheduler id="myScheduler" pool-size="5"/> <bean id="hello" class="hello.world.task.TestTask" /> </beans>

spring官网例子

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import java.util.concurrent.Future; import org.springframework.scheduling.annotation.Async; import org.springframework.scheduling.annotation.AsyncResult; import org.springframework.stereotype.Service; import org.springframework.web.client.RestTemplate; @Service public class GitHubLookupService { RestTemplate restTemplate = new RestTemplate(); @Async public Future<User> findUser(String user) throws InterruptedException { System.out.println( "Looking up " + user); User results = restTemplate.getForObject( "https://api.github.com/users/" + user, User.class); // Artificial delay of 1s for demonstration purposes Thread.sleep(1000L); return new AsyncResult<User>(results); } }

Async动作类

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package hello.world.task; import org.springframework.scheduling.annotation.Async; import org.springframework.scheduling.annotation.AsyncResult; import java.util.concurrent.Future; /** * Created by yang on 15-12-3. */ public class TestTask { @Async public Future<String> run() throws InterruptedException { System.out.println(Thread.currentThread().getName()); Thread.sleep( 20 * 1000); return new AsyncResult<String>( "hello"); } }

java测试类

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package hello.world; import hello.world.task.TestTask; import org.junit.Test; import org.junit.runner.RunWith; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.test.context.ContextConfiguration; import org.springframework.test.context.junit4.SpringJUnit4ClassRunner; import java.util.concurrent.ExecutionException; import java.util.concurrent.Future; /** * Created by yang on 15-11-9. */ @RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration( "classpath:spring-test.xml") public class HelloTest { @Autowired private TestTask testTask; @Test public void run() throws ExecutionException, InterruptedException { Future<String> hello = testTask.run(); System.out.println( "after 20 s?"); String h = hello.get(); System.out.println(h); } }

以上，它是以myexecutor的线程池来执行的.

@Scheduled

将@Async改为@Scheduled

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public class TestTask { @Scheduled(cron = "*/2 * * * * *") public void run() throws InterruptedException { System.out.println(Thread.currentThread().getName()); } }

看执行结果，它是以myscheduler的线程池来执行的，而且返回值只能是void.

同时使用 @Scheduled 和 @Async

不过注意，如果这样子使用了，异步执行的返回结果Future就不要这样子使用了，这时返回值只能是void.

同时使用这两个注解的效果，相当于@Scheduled负责调度，而executor负责执行。

看打印的线程可知:

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myExecutor-1 myExecutor-2 myExecutor-3 myExecutor-4 myExecutor-5 myExecutor-6 myExecutor-7 myExecutor-8 myExecutor-9 myExecutor-10 myExecutor-11 myExecutor-12 myExecutor-13 myExecutor-14 myExecutor-15 myExecutor-16

它是非常有规律的：每一个任务，都是下一条线程。然后轮回。