Why understanding request flow matters in Spring Boot - See It in Action

Understanding Request Flow in Spring Boot

📖 Scenario: You are building a simple web application using Spring Boot. To make your app work correctly, you need to understand how a user's request travels through your app from the moment it arrives until the response is sent back.

🎯 Goal: Build a basic Spring Boot controller that handles a web request and returns a greeting message. This will help you see the request flow in action.

📋 What You'll Learn

Create a Spring Boot controller class named GreetingController

Add a method that handles GET requests at the path /greet

Return a simple greeting message as a string

Configure the application to run as a Spring Boot app

💡 Why This Matters

🌍 Real World

Understanding request flow helps developers build web apps that respond correctly to user actions, like loading pages or submitting forms.

💼 Career

Most Java backend developer roles require knowledge of Spring Boot request handling to create APIs and web services.

1

Create the Controller Class

Create a public class called GreetingController and annotate it with @RestController.

Spring Boot

@RestController
public class GreetingController {
    // Your code here
}

Need a hint?

The @RestController annotation tells Spring Boot this class will handle web requests and return data directly.

2

Add a GET Request Handler Method

Inside GreetingController, add a public method called greet that returns a String. Annotate it with @GetMapping("/greet").

Spring Boot

@RestController
public class GreetingController {
    // Add the greet method here
}

Need a hint?

The @GetMapping annotation maps HTTP GET requests to this method.

3

Create the Main Application Class

Create a class called Application with a main method. Annotate the class with @SpringBootApplication and inside main, call SpringApplication.run(Application.class, args);.

Spring Boot

@RestController
public class GreetingController {

    @GetMapping("/greet")
    public String greet() {
        return "Hello, welcome to Spring Boot!";
    }
}

// Create Application class below

Need a hint?

The @SpringBootApplication annotation marks the main class for Spring Boot to start the app.

4

Run and Test the Application

Add the @SpringBootApplication import and ensure the application runs. The GreetingController should handle GET requests to /greet and return the greeting message.

Spring Boot

@RestController
public class GreetingController {

    @GetMapping("/greet")
    public String greet() {
        return "Hello, welcome to Spring Boot!";
    }
}

@SpringBootApplication
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

// Ensure all imports are present and run the app

Need a hint?

Make sure you have all necessary imports so the app compiles and runs.