使用Spring开启@Async异步方式(javaconfig配置)

目录

• Spring开启@Async异步(javaconfig配置)
• 应用场景
• 创建AsyncTask
• 创建spring配置AppConfig
• 测试
• Spring @Async Demo

Spring开启@Async异步(javaconfig配置)

在Spring中，基于@Async标注的方法，称之为异步方法；这些方法将在执行的时候，将会在独立的线程中被执行，调用者无需等待它的完成，即可继续其他的操作。

应用场景

• 某些耗时较长的而用户不需要等待该方法的处理结果
• 某些耗时较长的方法，后面的程序不需要用到这个方法的处理结果时

代码

创建AsyncTask

/**
 * 异步任务
 *
 * @author Peng
 */
public class AsyncTask {
    @Async
    public void doAsyncTask() throws InterruptedException {
        // 假设执行一个很耗时的任务
        Thread.sleep(10 * 1000);
        System.out.println("执行完成，我执行了10秒");
    }
}

创建spring配置AppConfig

/**
 * spring 配置
 *
 * @author Peng
 */
@Configuration
@EnableAsync
public class AppConfig {
    /**
     * 声明异步任务bean
     *
     * @return
     */
    @Bean
    public AsyncTask asyncTask() {
        return new AsyncTask();
    }
}

测试

/**
 * 异步测试
 *
 * @author Peng
 */
public class AppTest {
    public static void main(String[] args) throws InterruptedException {
        ApplicationContext ctx = new AnnotationConfigApplicationContext(AppConfig.class);
        AsyncTask task = ctx.getBean(AsyncTask.class);
        task.doAsyncTask();
        System.out.println("异步任务调用成功，返回客户端执行成功，异步任务继续执行");
    }
}

执行结果

异步任务调用成功，返回客户端执行成功，异步任务继续执行

执行完成，我执行了10秒

从结果可以看出，异步任务测试成功！

Spring @Async Demo

模拟一个业务场景：系统新用户注册成功后，异步发送邮件。

Project Directory

Maven Dependency

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>org.fool.springasync</groupId>
	<artifactId>springasync</artifactId>
	<name>springasync</name>
	<packaging>war</packaging>
	<version>1.0.0-BUILD-SNAPSHOT</version>
	<properties>
		<org.springframework-version>4.2.8.RELEASE</org.springframework-version>
	</properties>
	<dependencies>
		<!-- Spring -->
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-context</artifactId>
			<version>${org.springframework-version}</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-webmvc</artifactId>
			<version>${org.springframework-version}</version>
		</dependency>
		<dependency>
			<groupId>com.fasterxml.jackson.core</groupId>
			<artifactId>jackson-databind</artifactId>
			<version>2.8.1</version>
		</dependency>
		<dependency>
			<groupId>com.google.guava</groupId>
			<artifactId>guava</artifactId>
			<version>19.0</version>
		</dependency>
		<dependency>
			<groupId>org.apache.commons</groupId>
			<artifactId>commons-lang3</artifactId>
			<version>3.4</version>
		</dependency>
		<!-- @Inject -->
		<dependency>
			<groupId>javax.inject</groupId>
			<artifactId>javax.inject</artifactId>
			<version>1</version>
		</dependency>
		<!-- Servlet -->
		<dependency>
			<groupId>javax.servlet</groupId>
			<artifactId>javax.servlet-api</artifactId>
			<version>3.1.0</version>
			<scope>provided</scope>
		</dependency>
		<dependency>
			<groupId>javax.servlet.jsp</groupId>
			<artifactId>javax.servlet.jsp-api</artifactId>
			<version>2.3.1</version>
			<scope>provided</scope>
		</dependency>
		<dependency>
			<groupId>javax.servlet</groupId>
			<artifactId>jstl</artifactId>
			<version>1.2</version>
		</dependency>
		<!-- Test -->
		<dependency>
			<groupId>junit</groupId>
			<artifactId>junit</artifactId>
			<version>4.12</version>
			<scope>test</scope>
		</dependency>
	</dependencies>
	<build>
		<plugins>
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-eclipse-plugin</artifactId>
				<version>2.10</version>
				<configuration>
					<additionalProjectnatures>
						<projectnature>org.springframework.ide.eclipse.core.springnature</projectnature>
					</additionalProjectnatures>
					<additionalBuildcommands>
						<buildcommand>org.springframework.ide.eclipse.core.springbuilder</buildcommand>
					</additionalBuildcommands>
					<downloadSources>true</downloadSources>
					<downloadJavadocs>true</downloadJavadocs>
				</configuration>
			</plugin>
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-compiler-plugin</artifactId>
				<version>3.5.1</version>
				<configuration>
					<source>1.8</source>
					<target>1.8</target>
					<compilerArgument>-Xlint:all</compilerArgument>
					<showWarnings>true</showWarnings>
					<showDeprecation>true</showDeprecation>
				</configuration>
			</plugin>
			<plugin>
				<groupId>org.eclipse.jetty</groupId>
				<artifactId>jetty-maven-plugin</artifactId>
				<version>9.3.11.v20160721</version>
				<configuration>
					<scanIntervalSeconds>10</scanIntervalSeconds>
					<httpConnector>
						<port>8888</port>
					</httpConnector>
					<webApp>
						<contextPath>/springasync</contextPath>
					</webApp>
				</configuration>
			</plugin>
		</plugins>
	</build>
</project>

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee"
	xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
	id="WebApp_ID" version="3.0">
	<!-- The definition of the Root Spring Container shared by all Servlets and Filters -->
	<context-param>
		<param-name>contextConfigLocation</param-name>
		<param-value>/WEB-INF/spring/root-context.xml</param-value>
	</context-param>
	<!-- Creates the Spring Container shared by all Servlets and Filters -->
	<listener>
		<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
	</listener>
	<!-- Processes application requests -->
	<servlet>
		<servlet-name>appServlet</servlet-name>
		<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
		<init-param>
			<param-name>contextConfigLocation</param-name>
			<param-value>/WEB-INF/spring/appServlet/servlet-context.xml</param-value>
		</init-param>
		<load-on-startup>1</load-on-startup>
	</servlet>
	<servlet-mapping>
		<servlet-name>appServlet</servlet-name>
		<url-pattern>/</url-pattern>
	</servlet-mapping>
</web-app>

root-context.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

	<!-- Root Context: defines shared resources visible to all other web components -->
</beans>

servlet-context.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns="http://www.springframework.org/schema/mvc" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:beans="http://www.springframework.org/schema/beans" xmlns:context="http://www.springframework.org/schema/context"
	xmlns:task="http://www.springframework.org/schema/task"
	xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
		http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.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">
	<!-- DispatcherServlet Context: defines this servlet's request-processing infrastructure -->

	<!-- Enables the Spring MVC @Controller programming model -->
	<annotation-driven />
	<!-- Handles HTTP GET requests for /resources/** by efficiently serving up static resources in the ${webappRoot}/resources
		directory -->
	<resources mapping="/resources/**" location="/resources/" />
	<!-- Resolves views selected for rendering by @Controllers to .jsp resources in the /WEB-INF/views directory -->
	<beans:bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
		<beans:property name="prefix" value="/WEB-INF/views/" />
		<beans:property name="suffix" value=".jsp" />
	</beans:bean>
	<context:component-scan base-package="org.fool.springasync" />
</beans:beans>

AsyncConfig.java

package org.fool.springasync;
import java.util.concurrent.Executor;
import java.util.concurrent.ThreadPoolExecutor;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.context.support.PropertySourcesPlaceholderConfigurer;
import org.springframework.scheduling.annotation.EnableAsync;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;

@Configuration
@EnableAsync
@PropertySource("classpath:async.properties")
public class AsyncConfig {
	/** Set the ThreadPoolExecutor's core pool size. */
	@Value("${core.pool.size}")
    private Integer corePoolSize;

    /** Set the ThreadPoolExecutor's maximum pool size. */
	@Value("${max.pool.size}")
    private Integer maxPoolSize;

    /** Set the capacity for the ThreadPoolExecutor's BlockingQueue. */
	@Value("${queue.capacity}")
    private Integer queueCapacity;  

	@Value("${thread.name.prefix}")
    private String ThreadNamePrefix;

	@Bean
    public static PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfig() {
        return new PropertySourcesPlaceholderConfigurer();
    } 

    @Bean
    public Executor getAsyncExecutor() {
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        executor.setCorePoolSize(corePoolSize);
        executor.setMaxPoolSize(maxPoolSize);
        executor.setQueueCapacity(queueCapacity);
        executor.setThreadNamePrefix(ThreadNamePrefix);  

        // rejection-policy：当pool已经达到max size的时候，如何处理新任务
        // CALLER_RUNS：不在新线程中执行任务，而是有调用者所在的线程来执行
        executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());
        executor.initialize();
        return executor;
    }
}

Note:

AsyncConfig使用Annotation进行Spring Async的配置，当然也可以用XML的方式进行配置，只需要在servlet-context.xml中添加task的命名空间，同时加下如下两行配置：

<!-- Enables Spring Async -->
<task:annotation-driven executor="asyncExecutor"/>
<task:executor id="asyncExecutor" pool-size="2-4" queue-capacity="10"/>

<task:executor />配置参数：

id：当配置多个executor时，被@Async("id")指定使用；也被作为线程名的前缀。

pool-size：

• core size：最小的线程数，缺省：1
• max size：最大的线程数，缺省：Integer.MAX_VALUE

queue-capacity：当最小的线程数已经被占用满后，新的任务会被放进queue里面，当这个queue的capacity也被占满之后，pool里面会创建新线程处理这个任务，直到总线程数达到了max size，这时系统会拒绝这个任务并抛出TaskRejectedException异常（缺省配置的情况下，可以通过rejection-policy来决定如何处理这种情况）。缺省值为：Integer.MAX_VALUE

keep-alive：超过core size的那些线程，任务完成后，再经过这个时长（秒）会被结束掉

rejection-policy：当pool已经达到max size的时候，如何处理新任务

• ABORT（缺省）：抛出TaskRejectedException异常，然后不执行
• DISCARD：不执行，也不抛出异常
• DISCARD_OLDEST：丢弃queue中最旧的那个任务
• CALLER_RUNS：不在新线程中执行任务，而是有调用者所在的线程来执行

MailService.java

package org.fool.springasync;
import org.springframework.scheduling.annotation.Async;
import org.springframework.stereotype.Component;
@Component
public class MailService {

	@Async
	public void sendMail(String username) {
		System.out.println("Send Mail initialization...");
		System.out.println("Execute method asynchronously - " + Thread.currentThread().getName());

		try {
			Thread.sleep(5000);
			System.out.println("Welcome " + username);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}

		System.out.println("Send Mail Async done!!!");
	}
}

User.java

package org.fool.springasync;
import org.apache.commons.lang3.builder.ToStringBuilder;
import org.apache.commons.lang3.builder.ToStringStyle;
public class User {
	private Long id;
	private String username;
	private String password;
	public User() {
	}

	public User(Long id, String username, String password) {
		this.id = id;
		this.username = username;
		this.password = password;
	}

	public Long getId() {
		return id;
	}

	public void setId(Long id) {
		this.id = id;
	}

	public String getUsername() {
		return username;
	}

	public void setUsername(String username) {
		this.username = username;
	}

	public String getPassword() {
		return password;
	}

	public void setPassword(String password) {
		this.password = password;
	}

	@Override
	public String toString() {
		return ToStringBuilder.reflectionToString(this, ToStringStyle.SHORT_PREFIX_STYLE);
	}
}

UserService.java

package org.fool.springasync;
import javax.inject.Inject;
import org.springframework.stereotype.Service;
@Service
public class UserService {
	@Inject
	private MailService mailService;
	public void registerUser(User user) {
		System.out.println("insert user to db...");
		mailService.sendMail(user.getUsername());
		System.out.println("register done, please check the email later!!!");
	}
}

UserController.java

package org.fool.springasync;
import javax.inject.Inject;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
@RequestMapping("/user")
public class UserController {
	@Inject
	private UserService userService;
	@RequestMapping(value = "/testasync", method = RequestMethod.POST)
	@ResponseBody
	public User register(@RequestBody User user) {
		System.out.println(user);
		userService.registerUser(user);
		return user;
	}
}

Test

http://localhost:8888/springasync/user/testasync

POST请求（send两次）

Console Output

以上为个人经验，希望能给大家一个参考，也希望大家多多支持我们。