Updating to HttpStatusCode in Spring Boot 3

Omozegie AziegbeNovember 5th, 2024Last Updated: November 4th, 2024

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In Spring Boot 3, handling HTTP status codes has undergone a notable change. The introduction of HttpStatusCode marks a shift from the previously used HttpStatus, providing greater flexibility for handling HTTP responses. This article will explore the differences between HttpStatus and HttpStatusCode, how to use HttpStatusCode, and how to handle common cases that used to rely on HttpStatus.

1. Understanding HttpStatusCode in Spring Boot 3

HttpStatusCode is an interface that generalizes HTTP status codes, offering backward compatibility with HttpStatus but adding flexibility for future extensibility. While HttpStatus is an enum type with predefined constants, HttpStatusCode allows for a more dynamic, code-based approach to setting and checking status codes.

This shift to HttpStatusCode allows for more detailed control over HTTP status codes, providing a richer API with added methods for precise HTTP response handling. Previously, HttpStatus was used as an enum to represent status codes, but it had limitations, especially when handling codes outside its predefined set.

1.1 Differences Between HttpStatus and HttpStatusCode

Interface vs. Enum
- HttpStatus is an enum, limiting its extensibility.
- HttpStatusCode is an interface, allowing for more customization and the creation of custom status codes.
Methods
- HttpStatusCode provides additional methods like is1xxInformational(), is2xxSuccessful(), is3xxRedirection(), is4xxClientError(), is5xxServerError(), HttpStatusCode valueOf(int code)isError(), isSameCodeAs(HttpStatusCode other) and value() enabling more fine-grained checks.
Flexibility: HttpStatusCode can represent any HTTP status code dynamically, not just predefined ones, making it adaptable for non-standard codes if needed.
Reason Phrase: HttpStatus provides a getReasonPhrase() method for retrieving the default message associated with a status code. In HttpStatusCode, this method is removed, as it focuses only on the numeric code.
Compatibility: HttpStatusCode is backward-compatible with HttpStatus, meaning existing applications can still use HttpStatus values, making migration smoother.
Customizability: HttpStatusCode can be customized by developers to handle status codes more dynamically, whereas HttpStatus is limited to its predefined list of codes.

2. Example Using HttpStatusCode in a Controller

This section examines how to migrate a simple controller from HttpStatus to HttpStatusCode in Spring Boot 3. The controller manages various HTTP responses and demonstrates setting status codes using HttpStatusCode.

@RestController
public class ResponseController {

    @GetMapping("/check-status")
    public ResponseEntity<String> handleSuccessResponse() {
        HttpStatusCode statusCode = HttpStatusCode.valueOf(200);
        if (statusCode.is2xxSuccessful()) {
            return new ResponseEntity<>("Request successful", statusCode);
        }
        return new ResponseEntity<>("Request not successful", HttpStatusCode.valueOf(500));
    }

    @GetMapping("/redirect")
    public ResponseEntity<String> handleRedirectResponse() {
        HttpStatusCode statusCode = HttpStatusCode.valueOf(302);
        return new ResponseEntity<>("Redirecting to another resource", statusCode);
    }
   
}

In this example, the handleSuccessResponse method uses HttpStatusCode.valueOf(200) to set a 200 OK status code, returning a success message if the status is a 2xx successful code. If the check fails, it responds with a 500 Internal Server Error. Similarly, the handleRedirectResponse method utilizes HttpStatusCode.valueOf(302) to indicate a 302 Found status, used for redirecting to another resource.

This approach shows how to handle status codes more flexibly with HttpStatusCode, taking advantage of the new features in Spring Boot 3.

2. Adding a Custom Exception Handler

To handle exceptions that use HttpStatusCode, let’s add a global exception handler with @ControllerAdvice. This way, the application will handle exceptions consistently, returning meaningful error responses.

@ControllerAdvice
public class CustomExceptionHandler {

    @ExceptionHandler(CustomHttpException.class)
    public ResponseEntity<String> handleCustomException(CustomHttpException ex) {
        return new ResponseEntity<>(ex.getMessage(), ex.getStatusCode());
    }
}

In the handleCustomException method, we return a custom message with the status code provided by CustomException.

Now, let’s create a CustomHttpException class to demonstrate how custom exceptions can work seamlessly with HttpStatusCode.

public class CustomHttpException extends RuntimeException {
    private final HttpStatusCode statusCode;

    public CustomHttpException(String message, HttpStatusCode statusCode) {
        super(message);
        this.statusCode = statusCode;
    }

    public HttpStatusCode getStatusCode() {
        return statusCode;
    }
}

With this CustomHttpException, we can throw exceptions in our controller with a specific message and status code. When an endpoint throws this exception, CustomExceptionHandler catches it and returns a response with the message and status code.

2.1 Benefits of Migrating to HttpStatusCode

Future-Proofing: By using HttpStatusCode, applications are aligned with future versions of Spring, ensuring a smoother upgrade path.
Enhanced Flexibility: HttpStatusCode provides greater flexibility than HttpStatus, especially for dynamically defining status codes.
Cleaner Codebase: It simplifies exception handling, as we can easily assign custom codes without relying on the predefined constants of HttpStatus.

3. Conclusion

In this article, we explored how to migrate from HttpStatus to HttpStatusCode in Spring Boot 3, using a sample controller to illustrate a few HTTP response scenarios. By adopting HttpStatusCode, we can now handle HTTP status codes with more flexibility and simplicity, allowing for dynamic response management that is adaptable to future changes.