Spring Boot @ExceptionHandler Multiple Exceptions

In this blog post, we will explore how to handle multiple exceptions using @ExceptionHandler in a Spring Boot application and provide examples to illustrate its usage.

Setting Up the Global Exception Handler

To handle exceptions globally in a Spring Boot application, we need to define a GlobalExceptionHandler class annotated with @ControllerAdvice. Within this class, we will handle specific exceptions, multiple exceptions, and fallback exceptions.

Handling Specific Exceptions

In this example, we define @ExceptionHandler methods for handling specific exceptions individually. Each method takes the specific exception type as a parameter and implements the logic to handle that particular exception. You can customize the response based on the exception and return an appropriate ResponseEntity with the desired HTTP status code and response body.

@ControllerAdvice
public class GlobalExceptionHandler {
    @ExceptionHandler(FirstException.class)
    public ResponseEntity<String> handleFirstException(FirstException ex) {
        // Handle FirstException and return a custom response
    }

    @ExceptionHandler(SecondException.class)
    public ResponseEntity<String> handleSecondException(SecondException ex) {
        // Handle SecondException and return a custom response
    }
}

Handling Multiple Exceptions Together

To handle multiple exceptions together, you can use the {} notation within the @ExceptionHandler annotation. In this example, the handleMultipleExceptions method demonstrates handling ThirdException and FourthException together. This allows you to provide a unified handling mechanism for multiple exceptions, reducing code duplication.

@ControllerAdvice
public class GlobalExceptionHandler {
    @ExceptionHandler({ThirdException.class, FourthException.class})
    public ResponseEntity<String> handleMultipleExceptions(Exception ex) {
        // Handle ThirdException and FourthException together and return a custom response
    }
}

Fallback Exception Handling

The handleMultipleExceptions method acts as a fallback handler for any other unhandled exceptions that are not explicitly defined in the previous @ExceptionHandler methods. This ensures that you have a catch-all mechanism to handle unexpected exceptions and provide a generic error response.

@ControllerAdvice
public class GlobalExceptionHandler {
    @ExceptionHandler(Exception.class)
    public ResponseEntity<String> handleOtherExceptions(Exception ex) {
        // Handle any other unhandled exceptions and return a generic error response
    }
}

Conclusion

Using the @ExceptionHandler annotation in a Spring Boot application allows you to handle exceptions effectively and provide tailored responses based on the specific exception types. By defining multiple @ExceptionHandler methods within a @ControllerAdvice class, you can handle different exceptions separately, handle multiple exceptions together, and have a fallback mechanism for any unhandled exceptions. This approach enhances the error-handling capabilities of your application, resulting in a better user experience and improved reliability.