How to Handle GET Request in Spring Boot: Simple Guide

To handle a GET request in Spring Boot, create a controller class annotated with @RestController and add a method with @GetMapping specifying the URL path. This method returns the response data, which Spring Boot automatically converts to JSON or other formats.

Why This Happens

Sometimes, developers forget to use the correct annotations or method signatures to handle GET requests, causing Spring Boot to not recognize the endpoint or return errors.

java

import org.springframework.web.bind.annotation.RestController;

@RestController
public class MyController {

    public String getData() {
        return "Hello World";
    }
}

Output

404 Not Found error when accessing the endpoint because no mapping is defined.

The Fix

Add the @GetMapping annotation to the method to specify the URL path for the GET request. Also, ensure the class is annotated with @RestController so Spring Boot knows it handles web requests.

java

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class MyController {

    @GetMapping("/hello")
    public String getData() {
        return "Hello World";
    }
}

Output

When you visit http://localhost:8080/hello, the browser shows: Hello World

Prevention

Always annotate your controller classes with @RestController and your handler methods with the correct HTTP method annotations like @GetMapping. Use meaningful URL paths and test endpoints with tools like Postman or browser. Follow Spring Boot naming conventions and keep methods simple.

Related Errors

404 Not Found: Happens if the URL path in @GetMapping does not match the request URL.
405 Method Not Allowed: Occurs if the HTTP method (GET, POST) does not match the annotation on the method.
500 Internal Server Error: Can happen if the method throws an exception or returns an unsupported type.

Key Takeaways

Use @RestController on your class to handle web requests in Spring Boot.

Annotate methods with @GetMapping and specify the URL path to handle GET requests.

Test your endpoints with a browser or API tools to confirm they work.

Match HTTP methods and URL paths exactly to avoid 404 or 405 errors.

Keep controller methods simple and return supported data types like String or objects.