Handling Exceptions and Returning User-Friendly Messages in Spring Boot

In a Spring Boot application, it's crucial to handle exceptions gracefully and provide user-friendly error messages when something goes wrong. One way to achieve this is by using a controller advice, which allows you to intercept and handle exceptions globally for all controllers. In this blog post, we'll explore how to write a controller advice in Spring Boot that catches all exceptions and returns user-friendly messages.

Setting up the Controller Advice

First, let's create a new class annotated with @ControllerAdvice and implement the ResponseEntityExceptionHandler class. This class will handle exceptions globally for all controllers in our Spring Boot application.

import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler;

@ControllerAdvice
public class GlobalExceptionHandler extends ResponseEntityExceptionHandler {

}

Handling Exceptions

Next, we need to define exception handling methods within the GlobalExceptionHandler class. We'll annotate these methods with @ExceptionHandler and specify the exception types we want to handle.

@ExceptionHandler(Exception.class)
public ResponseEntity<Object> handleException(Exception ex) {
   // Handle general exceptions here
   // Create a custom error response object
   ErrorResponse errorResponse = new ErrorResponse(HttpStatus.INTERNAL_SERVER_ERROR, "An error occurred");
   return new ResponseEntity<>(errorResponse, HttpStatus.INTERNAL_SERVER_ERROR);
}

@ExceptionHandler(YourCustomException.class)
public ResponseEntity<Object> handleCustomException(YourCustomException ex) {
   // Handle specific exceptions here
   // Create a custom error response object
   ErrorResponse errorResponse = new ErrorResponse(HttpStatus.BAD_REQUEST, ex.getMessage());
   return new ResponseEntity<>(errorResponse, HttpStatus.BAD_REQUEST);
}

With this setup, any uncaught exceptions in your Spring Boot REST controllers will be intercepted by the GlobalExceptionHandler class. The exception handling methods can then create custom error response objects with user-friendly messages and appropriate HTTP status codes to return to the client.