Spring中@Async注解执行异步任务的方法

2023-09-11 21:18:04 156

引言

在业务处理中，有些业务使用异步的方式更为合理。比如在某个业务逻辑中，把一些数据存入到redis缓存中，缓存只是一个辅助的功能，成功或者失败对主业务并不会产生根本影响，这个过程可以通过异步的方法去进行。

Spring中通过在方法上设置@Async注解，可使得方法被异步调用。也就是说该方法会在调用时立即返回，而这个方法的实际执行交给Spring的TaskExecutor去完成。

代码示例

项目是一个普通的Spring的项目，Spring的配置文件：

两个Service类：

packagecom.lzumetal.ssm.anotation.service;
importorg.slf4j.Logger;
importorg.slf4j.LoggerFactory;
importorg.springframework.beans.factory.annotation.Autowired;
importorg.springframework.stereotype.Service;

importjava.util.concurrent.ExecutionException;
importjava.util.concurrent.Future;

/**
*业务Service
*/
@Service
publicclassBusinessService{

privatestaticfinalLoggerlog=LoggerFactory.getLogger(BusinessService.class);

@Autowired
privateCacheServicecacheService;


publicvoiddoBusiness(){
log.error("starttodealwithourbusiness");
cacheService.cacheData();
log.error("comleteserviceoperation");
}

/**
*获取异步方法执行的返回值
*/
publicvoiddoBusinessWithAsyncReturn()throwsExecutionException,InterruptedException{
log.error("starttodealwithourbusiness");
Futurefuture=cacheService.cacheDataWithReturn();
log.error(future.get());//future.get()方法是会阻塞的
log.error("comleteserviceoperation");
}
}

packagecom.lzumetal.ssm.anotation.service;

importorg.slf4j.Logger;
importorg.slf4j.LoggerFactory;
importorg.springframework.scheduling.annotation.Async;
importorg.springframework.scheduling.annotation.AsyncResult;
importorg.springframework.stereotype.Service;

importjava.util.concurrent.Future;
importjava.util.concurrent.TimeUnit;

/**
*缓存服务
*/
@Service
publicclassCacheService{

privatestaticfinalLoggerlog=LoggerFactory.getLogger(CacheService.class);


@Async(value="myexecutor")//指定执行任务的TaskExecutor
publicvoidcacheData(){
try{
TimeUnit.SECONDS.sleep(3L);
}catch(InterruptedExceptione){
e.printStackTrace();
}
log.error("successstoretheresulttocache");
}


@Async
publicFuturecacheDataWithReturn(){
try{
TimeUnit.SECONDS.sleep(3L);
}catch(InterruptedExceptione){
e.printStackTrace();
}
log.error("successstoretheresulttocache");
//返回的结果需要通过AsyncResult这个类包装
returnnewAsyncResult<>("Asyncoperationsuccess");
}
}

测试类：

packagecom.lzumetal.ssm.anotation.test;

importcom.lzumetal.ssm.anotation.service.BusinessService;
importorg.junit.Test;
importorg.junit.runner.RunWith;
importorg.springframework.beans.factory.annotation.Autowired;
importorg.springframework.test.context.ContextConfiguration;
importorg.springframework.test.context.junit4.SpringJUnit4ClassRunner;

importjava.util.concurrent.TimeUnit;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations={"classpath:spring-context.xml"})
publicclassMainTest{


@Autowired
privateBusinessServicebusinessService;


@Test
publicvoidtest()throwsInterruptedException{
businessService.doBusiness();
//不让主线程过早结束，否则控制台看不到异步方法中的输出内容
TimeUnit.SECONDS.sleep(5L);
}

@Test
publicvoidtestAsyncReturn()throwsException{
businessService.doBusinessWithAsyncReturn();
TimeUnit.SECONDS.sleep(5L);
}

}

执行test()方法的结果：

22:20:33,207 INFOmainsupport.DefaultTestContextBootstrapper:260-LoadeddefaultTestExecutionListenerclassnamesfromlocation[META-INF/spring.factories]:[org.springframework.test.context.web.ServletTestExecutionListener,org.springframework.test.context.support.DirtiesContextBeforeModesTestExecutionListener,org.springframework.test.context.support.DependencyInjectionTestExecutionListener,org.springframework.test.context.support.DirtiesContextTestExecutionListener,org.springframework.test.context.transaction.TransactionalTestExecutionListener,org.springframework.test.context.jdbc.SqlScriptsTestExecutionListener]
22:20:33,226 INFOmainsupport.DefaultTestContextBootstrapper:209-CouldnotinstantiateTestExecutionListener[org.springframework.test.context.web.ServletTestExecutionListener].Specifycustomlistenerclassesormakethedefaultlistenerclasses(andtheirrequireddependencies)available.Offendingclass:[javax/servlet/ServletContext]
22:20:33,227 INFOmainsupport.DefaultTestContextBootstrapper:187-UsingTestExecutionListeners:[org.springframework.test.context.support.DirtiesContextBeforeModesTestExecutionListener@100fc185,org.springframework.test.context.support.DependencyInjectionTestExecutionListener@643b1d11,org.springframework.test.context.support.DirtiesContextTestExecutionListener@2ef5e5e3,org.springframework.test.context.transaction.TransactionalTestExecutionListener@36d4b5c,org.springframework.test.context.jdbc.SqlScriptsTestExecutionListener@6d00a15d]22:20:33,324 INFOmainxml.XmlBeanDefinitionReader:317-LoadingXMLbeandefinitionsfromclasspathresource[spring-context.xml]
22:20:33,585 INFOmainsupport.GenericApplicationContext:583-Refreshingorg.springframework.context.support.GenericApplicationContext@4f7d0008:startupdate[WedMay3022:20:33CST2018];rootofcontexthierarchy
22:20:33,763 INFOmainconcurrent.ThreadPoolTaskExecutor:165-InitializingExecutorService
22:20:33,766 INFOmainsupport.PostProcessorRegistrationDelegate$BeanPostProcessorChecker:325-Bean'myexecutor'oftype[org.springframework.scheduling.config.TaskExecutorFactoryBean]isnoteligibleforgettingprocessedbyallBeanPostProcessors(forexample:noteligibleforauto-proxying)
22:20:33,767 INFOmainsupport.PostProcessorRegistrationDelegate$BeanPostProcessorChecker:325-Bean'myexecutor'oftype[org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor]isnoteligibleforgettingprocessedbyallBeanPostProcessors(forexample:noteligibleforauto-proxying)
22:20:34,107ERRORmainservice.BusinessService:24-starttodealwithourbusiness
22:20:34,113ERRORmainservice.BusinessService:26-comleteserviceoperation
22:20:37,166ERRORmyexecutor-1service.CacheService:28-successstoretheresulttocache
22:20:39,117 INFOThread-0support.GenericApplicationContext:984-Closingorg.springframework.context.support.GenericApplicationContext@4f7d0008:startupdate[WedMay3022:20:33CST2018];rootofcontexthierarchy
22:20:39,118 INFOThread-0concurrent.ThreadPoolTaskExecutor:203-ShuttingdownExecutorService

执行testAsyncReturn()方法的结果：

21:38:16,908 INFOmainsupport.DefaultTestContextBootstrapper:260-LoadeddefaultTestExecutionListenerclassnamesfromlocation[META-INF/spring.factories]:[org.springframework.test.context.web.ServletTestExecutionListener,org.springframework.test.context.support.DirtiesContextBeforeModesTestExecutionListener,org.springframework.test.context.support.DependencyInjectionTestExecutionListener,org.springframework.test.context.support.DirtiesContextTestExecutionListener,org.springframework.test.context.transaction.TransactionalTestExecutionListener,org.springframework.test.context.jdbc.SqlScriptsTestExecutionListener]
21:38:16,926 INFOmainsupport.DefaultTestContextBootstrapper:209-CouldnotinstantiateTestExecutionListener[org.springframework.test.context.web.ServletTestExecutionListener].Specifycustomlistenerclassesormakethedefaultlistenerclasses(andtheirrequireddependencies)available.Offendingclass:[javax/servlet/ServletContext]
21:38:16,927 INFOmainsupport.DefaultTestContextBootstrapper:187-UsingTestExecutionListeners:[org.springframework.test.context.support.DirtiesContextBeforeModesTestExecutionListener@100fc185,org.springframework.test.context.support.DependencyInjectionTestExecutionListener@643b1d11,org.springframework.test.context.support.DirtiesContextTestExecutionListener@2ef5e5e3,org.springframework.test.context.transaction.TransactionalTestExecutionListener@36d4b5c,org.springframework.test.context.jdbc.SqlScriptsTestExecutionListener@6d00a15d]21:38:17,025 INFOmainxml.XmlBeanDefinitionReader:317-LoadingXMLbeandefinitionsfromclasspathresource[spring-context.xml]
21:38:17,263 INFOmainsupport.GenericApplicationContext:583-Refreshingorg.springframework.context.support.GenericApplicationContext@4f7d0008:startupdate[WedMay3021:38:17CST2018];rootofcontexthierarchy
21:38:17,405 INFOmainconcurrent.ThreadPoolTaskExecutor:165-InitializingExecutorService
21:38:17,407 INFOmainsupport.PostProcessorRegistrationDelegate$BeanPostProcessorChecker:325-Bean'myexecutor'oftype[org.springframework.scheduling.config.TaskExecutorFactoryBean]isnoteligibleforgettingprocessedbyallBeanPostProcessors(forexample:noteligibleforauto-proxying)
21:38:17,407 INFOmainsupport.PostProcessorRegistrationDelegate$BeanPostProcessorChecker:325-Bean'myexecutor'oftype[org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor]isnoteligibleforgettingprocessedbyallBeanPostProcessors(forexample:noteligibleforauto-proxying)
21:38:17,692ERRORmainservice.BusinessService:35-starttodealwithourbusiness
21:38:20,833ERRORmyexecutor-1service.CacheService:39-successstoretheresulttocache
21:38:20,834ERRORmainservice.BusinessService:37-Asyncoperationsuccess
21:38:20,835ERRORmainservice.BusinessService:38-comleteserviceoperation
21:38:25,838 INFOThread-0support.GenericApplicationContext:984-Closingorg.springframework.context.support.GenericApplicationContext@4f7d0008:startupdate[WedMay3021:38:17CST2018];rootofcontexthierarchy
21:38:25,839 INFOThread-0concurrent.ThreadPoolTaskExecutor:203-ShuttingdownExecutorService

@Async的使用注意点

返回值：不要返回值直接void；需要返回值用AsyncResult或者CompletableFuture
可自定义执行器并指定例如：@Async("otherExecutor")
@Async必须不同类间调用：A类—>B类.C方法()（@Async注释在B类/方法中），如果在同一个类中调用，会变同步执行,例如:A类.B()—>A类.@AsyncC()。
@Async也可以加到类，表示这个类的所有方法都是异步执行，并且方法上的注解会覆盖类上的注解。但一般不这么用！

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Spring中@Async注解执行异步任务的方法

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