How is exception handling implemented in applications using the Spring Framework?

In Spring Framework, exception handling is usually implemented using the @ExceptionHandler annotation in controllers or globally through @ControllerAdvice.

Example of local handling in a controller:

@RestController
public class MyController {

    @GetMapping("/example")
    public String example() {
        if (true) {
            throw new IllegalArgumentException("Parameter error");
        }
        return "OK";
    }

    @ExceptionHandler(IllegalArgumentException.class)
    public ResponseEntity<String> handleIllegalArgument(IllegalArgumentException ex) {
        return ResponseEntity.badRequest().body(ex.getMessage());
    }
}

For global handling, create a class with @ControllerAdvice:

@ControllerAdvice
public class GlobalExceptionHandler {

    @ExceptionHandler(Exception.class)
    public ResponseEntity<String> handleAllExceptions(Exception ex) {
        return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR)
                             .body("Internal server error: " + ex.getMessage());
    }
}

This approach allows centralized error handling, returning understandable responses to clients, and maintaining controller cleanliness.