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

	4.0.0
	org.fool.springasync
	springasync
	springasync
	war
	1.0.0-BUILD-SNAPSHOT
	
		4.2.8.RELEASE
	
	
		
		
			org.springframework
			spring-context
			${org.springframework-version}
		
		
			org.springframework
			spring-webmvc
			${org.springframework-version}
		
		
			com.fasterxml.jackson.core
			jackson-databind
			2.8.1
		
		
			com.google.guava
			guava
			19.0
		
		
			org.apache.commons
			commons-lang3
			3.4
		
		
		
			javax.inject
			javax.inject
			1
		
		
		
			javax.servlet
			javax.servlet-api
			3.1.0
			provided
		
		
			javax.servlet.jsp
			javax.servlet.jsp-api
			2.3.1
			provided
		
		
			javax.servlet
			jstl
			1.2
		
		
		
			junit
			junit
			4.12
			test
		
	
	
		
			
				org.apache.maven.plugins
				maven-eclipse-plugin
				2.10
				
					
						org.springframework.ide.eclipse.core.springnature
					
					
						org.springframework.ide.eclipse.core.springbuilder
					
					true
					true
				
			
			
				org.apache.maven.plugins
				maven-compiler-plugin
				3.5.1
				
					1.8
					1.8
					-Xlint:all
					true
					true
				
			
			
				org.eclipse.jetty
				jetty-maven-plugin
				9.3.11.v20160721
				
					10
					
						8888
					
					
						/springasync
					
				
			
		
	

web.xml

	
	
		contextConfigLocation
		/WEB-INF/spring/root-context.xml
	
	
	
		org.springframework.web.context.ContextLoaderListener
	
	
	
		appServlet
		org.springframework.web.servlet.DispatcherServlet
		
			contextConfigLocation
			/WEB-INF/spring/appServlet/servlet-context.xml
		
		1
	
	
		appServlet
		/
	

root-context.xml

servlet-context.xml

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：

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脚本之家。