Asynchronous Code with Spring 3 – Simple as an annotation

After reviewing some of the features of Spring 3, i decided to test out the asychronous features via annotation. And below is all the code i needed in order to have a function executed asynchronously in my application:

   1: public class Asyncher {

   2:     @Async

   3:     public void myMethod(int i) {

   4:         try {

   5:             Thread.sleep(2000);

   6:         } catch (InterruptedException e) {

   7:             e.printStackTrace();

   8:         }

   9:         System.out.println("Running for " + i);

  10:     }

  11:  

  12:     public static void main(String[] args) throws InterruptedException {

  13:         ApplicationContext ctx = new ClassPathXmlApplicationContext("appContext.xml");

  14:         Asyncher a = ctx.getBean("asyncher", Asyncher.class);

  15:         for (int i=0; i<10;i++) {

  16:                 a.myMethod(i);

  17:         }      

  18:  

  19:         ThreadPoolTaskExecutor t = ctx.getBean("myExecutor",ThreadPoolTaskExecutor.class);

  20:         while (t.getActiveCount() > 0) {

  21:             System.out.println("Number of tasks left: " + t.getActiveCount());

  22:             Thread.sleep(2000);

  23:         }

  24:         t.shutdown();

  25:     }

  26: }

Hard to believe, but all i needed to do was add the Async annotation on line 2 to my function and it works. of course we need a few lines in our application Context to make this work, but here they are:

   1: <?xml version="1.0" encoding="UTF-8"?>

   2: <beans xmlns="http://www.springframework.org/schema/beans"

   3:        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:task="http://www.springframework.org/schema/task"

   4:        xmlns:context="http://www.springframework.org/schema/context"

   5:        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

   6:  

   7:     <task:annotation-driven executor="myExecutor" />

   8:     <task:executor id="myExecutor" pool-size="2"/>

   9:     <bean id="asyncher" class="Asyncher"/>

  10:  

  11: </beans>

This same method can be used to create scheduled jobs as well, by changing or adding on line 7 the scheduler attribute and then adding in a scheduler bean

<task:scheduler id="myScheduler" pool-size="10"/>

You can read about it in the docs here