Global Exception Handling with @ControllerAdvice

When building a Spring Boot application, it is crucial to consider how to handle exceptions and errors that might occur during the application's execution. One approach to achieve this is by using the @ControllerAdvice annotation, which allows for global exception handling.

The @ControllerAdvice annotation enables a class to be designated as an exception handler for all the controllers within a Spring Boot application. This means that if an exception is thrown from any controller, the @ControllerAdvice annotated class can intercept it and provide a customized response or redirect it to an appropriate error page.

Here is a step-by-step guide on how to utilize @ControllerAdvice for global exception handling in your Spring Boot application:

Step 1: Create a GlobalExceptionHandler Class

First, create a class and annotate it with @ControllerAdvice. This class will contain methods that handle specific exceptions.

@ControllerAdvice
public class GlobalExceptionHandler {

    // Exception handling methods
}

Step 2: Define Exception Handling Methods

Inside the GlobalExceptionHandler class, define methods that handle specific exceptions. Each method should be annotated with @ExceptionHandler and specify the exception(s) it handles. For example, let's handle a NotFoundException:

@ExceptionHandler(NotFoundException.class)
public ResponseEntity<ErrorResponse> handleNotFoundException(NotFoundException ex) {
    ErrorResponse error = new ErrorResponse(HttpStatus.NOT_FOUND, ex.getMessage());
    return new ResponseEntity<>(error, HttpStatus.NOT_FOUND);
}

In this example, the method handleNotFoundException() is triggered when a NotFoundException is thrown. It creates a customized ErrorResponse object and returns it with an appropriate HTTP status code.

Step 3: Customize the ErrorResponse Class

Create a custom ErrorResponse class that represents the error response structure. This class should include properties for the HTTP status code and the error message.

public class ErrorResponse {
    private HttpStatus status;
    private String message;

    // Constructor, getters, and setters
}

Step 4: Enable Global Exception Handling

To enable global exception handling, add the @EnableWebMvc annotation to your main application class.

@SpringBootApplication
@EnableWebMvc
public class MyApplication {

    public static void main(String[] args) {
        SpringApplication.run(MyApplication.class, args);
    }
}

By annotating the MyApplication class with @EnableWebMvc, it activates Spring MVC capabilities, including global exception handling through @ControllerAdvice.

Conclusion

Using @ControllerAdvice, you can effectively handle exceptions globally in your Spring Boot application. This approach allows for centralized exception handling, reducing code duplication and improving the application's overall maintainability. By providing customized error responses and appropriate HTTP status codes, you can enhance the user experience and the application's stability.