@Async for async methods in Spring Boot - Mini Project: Build & Apply

Using @Async for Async Methods in Spring Boot

📖 Scenario: You are building a Spring Boot application that needs to perform a time-consuming task without blocking the main thread. To improve user experience, you want to run this task asynchronously.

🎯 Goal: Learn how to use the @Async annotation in Spring Boot to run methods asynchronously, so the main thread can continue working while the task runs in the background.

📋 What You'll Learn

Create a Spring Boot service class with a method that simulates a long-running task

Enable asynchronous processing in the Spring Boot application

Annotate the long-running method with @Async to make it run asynchronously

Call the asynchronous method from a controller and return a response immediately

💡 Why This Matters

🌍 Real World

Asynchronous methods help improve responsiveness in web applications by running slow tasks in the background.

💼 Career

Knowing how to use @Async is important for backend developers working with Spring Boot to build scalable and efficient applications.

1

Create a service class with a long-running method

Create a Spring service class called TaskService with a method public void runLongTask() that simulates a long task by sleeping for 3000 milliseconds inside a try-catch block.

Spring Boot

import org.springframework.stereotype.Service;

@Service
public class TaskService {
    // Your code here
}

Need a hint?

Use Thread.sleep(3000) inside runLongTask() to simulate a delay.

2

Enable asynchronous processing in the application

In your main Spring Boot application class, add the @EnableAsync annotation above the class declaration to enable async support.

Spring Boot

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
// Add import for EnableAsync

@SpringBootApplication
// Your code here
public class AsyncDemoApplication {
    public static void main(String[] args) {
        SpringApplication.run(AsyncDemoApplication.class, args);
    }
}

Need a hint?

Import and add @EnableAsync above your main application class.

3

Make the long-running method asynchronous

In the TaskService class, add the @Async annotation above the runLongTask() method to make it run asynchronously.

Spring Boot

import org.springframework.stereotype.Service;
import org.springframework.scheduling.annotation.Async;

@Service
public class TaskService {
    // Add @Async annotation here
    public void runLongTask() {
        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
        }
    }
}

// Rest of the code unchanged

Need a hint?

Import @Async and place it just above runLongTask().

4

Call the async method from a controller

Create a Spring REST controller class called TaskController with a GET endpoint /start-task that calls taskService.runLongTask() and immediately returns the string "Task started".

Spring Boot

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.beans.factory.annotation.Autowired;

@RestController
public class TaskController {
    @Autowired
    private TaskService taskService;

    // Add GET endpoint /start-task here
}

Need a hint?

Create a controller with a GET method that calls the async method and returns immediately.