Spring async service example - Learn Java by Examples

The Spring async service example show you how to use Spring @Async Thread execution together with Java’s Future callback. We are using Spring @Async to fire up a new thread and get the result in a later time. This is the best solution in case you want to make a time consuming task.

Let’s begin:

Spring Dependencies
Spring have built-in @Async for the asynchronous thread callbacks, so we need the following dependencies.

<?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/xsd/maven-4.0.0.xsd">

    <modelVersion>4.0.0</modelVersion>
    <groupId>com.javabycode.spring.core</groupId>
    <artifactId>spring-async-annotation-example</artifactId>
    <version>1.0.0-SNAPSHOT</version>
    <url>http://javabycode.com</url>
    <name>SPRING - ${project.artifactId}</name>

    <properties>
        <spring.version>4.3.0.RELEASE</spring.version>
    </properties>

    <dependencies>
        <!-- spring dependencies -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${spring.version}</version>
        </dependency>
    </dependencies>
    
</project>

<?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/xsd/maven-4.0.0.xsd">

<groupId>com.javabycode.spring.core</groupId>

<artifactId>spring-async-annotation-example</artifactId>

<version>1.0.0-SNAPSHOT</version>

<url>http://javabycode.com</url>

<name>SPRING - ${project.artifactId}</name>

<spring.version>4.3.0.RELEASE</spring.version>

</properties>

<groupId>org.springframework</groupId>

<artifactId>spring-core</artifactId>

<version>${spring.version}</version>

</dependency>

<groupId>org.springframework</groupId>

<artifactId>spring-context</artifactId>

<version>${spring.version}</version>

</dependency>

</dependencies>

</project>

Spring Application Java Configuration

In this Spring async service example, we are creating Spring application which supports asynchronous execution.

package com.javabycode;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.annotation.EnableAsync;

@EnableAsync
@Configuration
@ComponentScan("com.javabycode")
public class AppConfig {

}

package com.javabycode;

import org.springframework.context.annotation.ComponentScan;

import org.springframework.context.annotation.Configuration;

import org.springframework.scheduling.annotation.EnableAsync;

@EnableAsync

@Configuration

@ComponentScan("com.javabycode")

public class AppConfig {

}

Dig deeper:
@EnableAsync annotation: such as its name, it enables the asynchronous processing. Without this annotation the methods annotated with the @Async will not execute asynchronously.

Mail engine with Spring @Async Method
Now we create a simple mail engine with the sending email method which allow sending mail and receive the result in 10 seconds later. This method is annotated with Spring @Async annotation. The return of the method is a Future which is one of the new libraries of Java 7. A Future object represents the result of an asynchronous computation.

package com.javabycode;

import org.springframework.scheduling.annotation.Async;
import org.springframework.scheduling.annotation.AsyncResult;
import org.springframework.stereotype.Component;

import java.util.Timer;
import java.util.TimerTask;
import java.util.concurrent.Future;

@Component
public class MyMailEngine {
	static int interval = 10; //10 seconds

    @Async
    public Future<Boolean> sendMail() throws InterruptedException {
        System.out.println("Sending mail..");
        setUpTimer();// countdown timer
        Thread.sleep(1000 * 10);
        System.out.println("Sending mail completed");
        return new AsyncResult<Boolean>(true);
    }
    
    public void setUpTimer(){
        final Timer timer = new Timer();
        timer.scheduleAtFixedRate(new TimerTask() {
            public void run() {
                System.out.println(setInterval(timer)+"s");

            }
        }, 1000, 1000);            	
    }
    
    static final int setInterval(Timer timer) {
        if (interval == 1)
            timer.cancel();
        return --interval;
    }    
}

package com.javabycode;

import org.springframework.scheduling.annotation.Async;

import org.springframework.scheduling.annotation.AsyncResult;

import org.springframework.stereotype.Component;

import java.util.Timer;

import java.util.TimerTask;

import java.util.concurrent.Future;

@Component

public class MyMailEngine {

static int interval = 10; //10 seconds

@Async

public Future<Boolean> sendMail() throws InterruptedException {

System.out.println("Sending mail..");

setUpTimer();// countdown timer

Thread.sleep(1000 * 10);

System.out.println("Sending mail completed");

return new AsyncResult<Boolean>(true);

}

public void setUpTimer(){

final Timer timer = new Timer();

timer.scheduleAtFixedRate(new TimerTask() {

public void run() {

System.out.println(setInterval(timer)+"s");

}

}, 1000, 1000);

}

static final int setInterval(Timer timer) {

if (interval == 1)

timer.cancel();

return --interval;

}

Notice: In our mail engine, we add a countdown timer 10 seconds which help you get the visual output

Test Spring @Async Methods
In this Spring async service example, we create a main class to test the sending email process using Spring @Async Methods above

package com.javabycode;

import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;

public class MySpringApplication {

    public static void main(String...args) throws InterruptedException, ExecutionException {

        ApplicationContext context = new AnnotationConfigApplicationContext(AppConfig.class);
    	MyMailEngine mailEngine = context.getBean(MyMailEngine.class);

    	System.out.println("Mail sending will run immediately.");
        Future<Boolean> future = mailEngine.sendMail();        
        Boolean result = future.get();
        System.out.println("Mail send result: " + result);
    }
}

package com.javabycode;

import org.springframework.context.ApplicationContext;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

import java.util.concurrent.ExecutionException;

import java.util.concurrent.Future;

public class MySpringApplication {

public static void main(String...args) throws InterruptedException, ExecutionException {

ApplicationContext context = new AnnotationConfigApplicationContext(AppConfig.class);

MyMailEngine mailEngine = context.getBean(MyMailEngine.class);

System.out.println("Mail sending will run immediately.");

Future<Boolean> future = mailEngine.sendMail();

Boolean result = future.get();

System.out.println("Mail send result: " + result);

}

Run the main above, the console will print the following message.

Sending mail..
9s
8s
7s
6s
5s
4s
3s
2s
1s
0s
Sending mail completed
Mail send result: true

Sending mail..

Sending mail completed

Mail send result: true

That’s all on the Spring async service example.

References
Future JavaDoc
Timer JavaDoc
@EnableAsync JavaDoc
@Async JavaDoc

Download complete source code, click link below

spring-async-annotation-example.zip (52 downloads)

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