Spring中@Async注解执行异步任务 & @Async Could not find unique TaskExecutor bean; NoUniqueBeanDefinitionException;

Spring中@Async注解执行异步任务

https://segmentfault.com/a/1190000015190901

 

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：

<?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-4.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task.xsd"> <!-- 包扫描 --> <context:component-scan base-package="com.lzumetal.ssm"/> <!-- 执行异步任务的线程池TaskExecutor --> <task:executor id="myexecutor" pool-size="5" /> <task:annotation-driven executor="myexecutor"/> </beans>

两个Service类：

package com.lzumetal.ssm.anotation.service; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; import java.util.concurrent.ExecutionException; import java.util.concurrent.Future; /** * 业务Service */ @Service public class BusinessService { private static final Logger log = LoggerFactory.getLogger(BusinessService.class); @Autowired private CacheService cacheService; public void doBusiness() { log.error("start to deal with our business"); cacheService.cacheData(); log.error("comlete service operation"); } /** * 获取异步方法执行的返回值 */ public void doBusinessWithAsyncReturn() throws ExecutionException, InterruptedException { log.error("start to deal with our business"); Future<String> future = cacheService.cacheDataWithReturn(); log.error(future.get()); //future.get()方法是会阻塞的 log.error("comlete service operation"); } }

package com.lzumetal.ssm.anotation.service; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.scheduling.annotation.Async; import org.springframework.scheduling.annotation.AsyncResult; import org.springframework.stereotype.Service; import java.util.concurrent.Future; import java.util.concurrent.TimeUnit; /** * 缓存服务 */ @Service public class CacheService { private static final Logger log = LoggerFactory.getLogger(CacheService.class); @Async(value = "myexecutor") //指定执行任务的TaskExecutor public void cacheData() { try { TimeUnit.SECONDS.sleep(3L); } catch (InterruptedException e) { e.printStackTrace(); } log.error("success store the result to cache"); } @Async public Future<String> cacheDataWithReturn() { try { TimeUnit.SECONDS.sleep(3L); } catch (InterruptedException e) { e.printStackTrace(); } log.error("success store the result to cache"); //返回的结果需要通过AsyncResult这个类包装 return new AsyncResult<>("Async operation success"); } } 

测试类：

package com.lzumetal.ssm.anotation.test; import com.lzumetal.ssm.anotation.service.BusinessService; 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.TimeUnit; @RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration(locations = {"classpath:spring-context.xml"}) public class MainTest { @Autowired private BusinessService businessService; @Test public void test() throws InterruptedException { 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 public void testAsyncReturn() throws Exception { businessService.doBusinessWithAsyncReturn(); TimeUnit.SECONDS.sleep(5L); } }

执行test()方法的结果：

22:20:33,207 INFO main support.DefaultTestContextBootstrapper:260 - Loaded default TestExecutionListener class names from location [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 INFO main support.DefaultTestContextBootstrapper:209 - Could not instantiate TestExecutionListener [org.springframework.test.context.web.ServletTestExecutionListener]. Specify custom listener classes or make the default listener classes (and their required dependencies) available. Offending class: [javax/servlet/ServletContext] 22:20:33,227 INFO main support.DefaultTestContextBootstrapper:187 - Using TestExecutionListeners: [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 INFO main xml.XmlBeanDefinitionReader:317 - Loading XML bean definitions from class path resource [spring-context.xml] 22:20:33,585 INFO main support.GenericApplicationContext:583 - Refreshing org.springframework.context.support.GenericApplicationContext@4f7d0008: startup date [Wed May 30 22:20:33 CST 2018]; root of context hierarchy 22:20:33,763 INFO main concurrent.ThreadPoolTaskExecutor:165 - Initializing ExecutorService 22:20:33,766 INFO main support.PostProcessorRegistrationDelegate$BeanPostProcessorChecker:325 - Bean 'myexecutor' of type [org.springframework.scheduling.config.TaskExecutorFactoryBean] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying) 22:20:33,767 INFO main support.PostProcessorRegistrationDelegate$BeanPostProcessorChecker:325 - Bean 'myexecutor' of type [org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying) 22:20:34,107 ERROR main service.BusinessService:24 - start to deal with our business 22:20:34,113 ERROR main service.BusinessService:26 - comlete service operation 22:20:37,166 ERROR myexecutor-1 service.CacheService:28 - success store the result to cache 22:20:39,117 INFO Thread-0 support.GenericApplicationContext:984 - Closing org.springframework.context.support.GenericApplicationContext@4f7d0008: startup date [Wed May 30 22:20:33 CST 2018]; root of context hierarchy 22:20:39,118 INFO Thread-0 concurrent.ThreadPoolTaskExecutor:203 - Shutting down ExecutorService

执行testAsyncReturn()方法的结果：

21:38:16,908 INFO main support.DefaultTestContextBootstrapper:260 - Loaded default TestExecutionListener class names from location [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 INFO main support.DefaultTestContextBootstrapper:209 - Could not instantiate TestExecutionListener [org.springframework.test.context.web.ServletTestExecutionListener]. Specify custom listener classes or make the default listener classes (and their required dependencies) available. Offending class: [javax/servlet/ServletContext] 21:38:16,927 INFO main support.DefaultTestContextBootstrapper:187 - Using TestExecutionListeners: [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 INFO main xml.XmlBeanDefinitionReader:317 - Loading XML bean definitions from class path resource [spring-context.xml] 21:38:17,263 INFO main support.GenericApplicationContext:583 - Refreshing org.springframework.context.support.GenericApplicationContext@4f7d0008: startup date [Wed May 30 21:38:17 CST 2018]; root of context hierarchy 21:38:17,405 INFO main concurrent.ThreadPoolTaskExecutor:165 - Initializing ExecutorService 21:38:17,407 INFO main support.PostProcessorRegistrationDelegate$BeanPostProcessorChecker:325 - Bean 'myexecutor' of type [org.springframework.scheduling.config.TaskExecutorFactoryBean] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying) 21:38:17,407 INFO main support.PostProcessorRegistrationDelegate$BeanPostProcessorChecker:325 - Bean 'myexecutor' of type [org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying) 21:38:17,692 ERROR main service.BusinessService:35 - start to deal with our business 21:38:20,833 ERROR myexecutor-1 service.CacheService:39 - success store the result to cache 21:38:20,834 ERROR main service.BusinessService:37 - Async operation success 21:38:20,835 ERROR main service.BusinessService:38 - comlete service operation 21:38:25,838 INFO Thread-0 support.GenericApplicationContext:984 - Closing org.springframework.context.support.GenericApplicationContext@4f7d0008: startup date [Wed May 30 21:38:17 CST 2018]; root of context hierarchy 21:38:25,839 INFO Thread-0 concurrent.ThreadPoolTaskExecutor:203 - Shutting down ExecutorService

@Async的使用注意点

1. 返回值：不要返回值直接void；需要返回值用AsyncResult或者CompletableFuture
2. 可自定义执行器并指定例如：@Async("otherExecutor")
3. @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.@Async C()。
4. @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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@Async Could not find unique TaskExecutor bean; NoUniqueBeanDefinitionException;

  https://blog.csdn.net/chenping1993/article/details/103881649

 

异步任务，项目启动或接口调用，控制台报错：Could not find unique TaskExecutor bean;

或者报错：org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type 'org.springframework.core.task.TaskExecutor' available: expected single matching bean but found 2: applicationTaskExecutor,taskScheduler

原因为：@Async所注解的方法存在相同的方法名，或者同一个异步任务被多个任务同时调用

解决方法：

1、将@Async所注解的方法名修改为不同的方法名

2、增加异步任务配置类：

import org.springframework.aop.interceptor.AsyncUncaughtExceptionHandler;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.annotation.AsyncConfigurer;
import org.springframework.scheduling.annotation.EnableAsync;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
 
import java.util.concurrent.Executor;
 
/**
 * @description 异步任务配置类，为防止异步任务如下错误：
 * No qualifying bean of type 'org.springframework.core.task.TaskExecutor' available:
 * expected single matching bean but found 2: applicationTaskExecutor,taskScheduler
 * @author: chenping
 * @create: 2020-01-17
 **/
@Configuration
@ComponentScan("cn.com.*.*.*.service")//异步任务所在的包
@EnableAsync //开启异步任务支持
public class TaskExecutorConfig implements AsyncConfigurer {
 
    /**
     * @description:  实现AsyncConfigurer接口并重写getAsyncExecutor方法，
     *  并返回一个ThreadPoolTaskExecutor，这样我们就获得了一个基于线程池TaskExecutor
     * @param:
     * @return: java.util.concurrent.Executor
     * @author: chenping
     * @date: 2020/1/17
     **/
    @Override
    public Executor getAsyncExecutor() {
        ThreadPoolTaskExecutor taskExecutor = new ThreadPoolTaskExecutor();
        taskExecutor.setCorePoolSize(10);
        taskExecutor.setMaxPoolSize(80);
        taskExecutor.setQueueCapacity(100);
        taskExecutor.initialize();
        return taskExecutor;
    }
 
    @Override
    public AsyncUncaughtExceptionHandler getAsyncUncaughtExceptionHandler() {
        return null;
    }
}