Spring Boot – error handling

Spring Boot – Error Handling

Error handling in Spring Boot is a crucial aspect of building robust applications. It involves managing exceptions and errors that occur during the execution of a program, ensuring that the application can gracefully handle unexpected situations. Proper error handling not only improves user experience by providing meaningful error messages but also aids in debugging and maintaining the application.

Solution

1. Using @ControllerAdvice and @ExceptionHandler

Spring Boot provides a powerful mechanism to handle exceptions globally using @ControllerAdvice and @ExceptionHandler annotations. This approach allows you to centralize error handling logic, making it easier to manage and maintain.

Sample Code:

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.context.request.WebRequest

@ControllerAdvice
class GlobalExceptionHandler {

    @ExceptionHandler(value = [IllegalArgumentException::class])
    fun handleIllegalArgumentException(ex: IllegalArgumentException, request: WebRequest): ResponseEntity<String> {
        return ResponseEntity("Invalid argument: ${ex.message}", HttpStatus.BAD_REQUEST)
    }

    @ExceptionHandler(value = [Exception::class])
    fun handleGenericException(ex: Exception, request: WebRequest): ResponseEntity<String> {
        return ResponseEntity("An error occurred: ${ex.message}", HttpStatus.INTERNAL_SERVER_ERROR)
    }
}

Output:

• When an IllegalArgumentException is thrown, the response will be a 400 Bad Request with a message like "Invalid argument: [error message]".
• For any other exceptions, a 500 Internal Server Error will be returned with a message "An error occurred: [error message]".

Advantages:

• Centralized error handling logic.
• Easy to manage and extend for new exception types.
• Provides a clear separation of concerns.

Disadvantages:

• May become complex if too many exception types are handled.
• Requires understanding of Spring's exception handling mechanism.

2. Using ResponseStatusException

Spring Boot also allows you to throw ResponseStatusException directly from your controller methods. This approach is straightforward and useful for simple error handling scenarios.

Sample Code:

import org.springframework.http.HttpStatus
import org.springframework.web.bind.annotation.GetMapping
import org.springframework.web.bind.annotation.RequestParam
import org.springframework.web.bind.annotation.RestController
import org.springframework.web.server.ResponseStatusException

@RestController
class SampleController {

    @GetMapping("/example")
    fun example(@RequestParam value: String?): String {
        if (value.isNullOrEmpty()) {
            throw ResponseStatusException(HttpStatus.BAD_REQUEST, "Value parameter is required")
        }
        return "Value is $value"
    }
}

Output:

• If the value parameter is missing or empty, a 400 Bad Request will be returned with the message "Value parameter is required".

Advantages:

• Simple and concise for straightforward error handling.
• No need for additional classes or annotations.

Disadvantages:

• Error handling logic is scattered across controller methods.
• Not suitable for complex error handling scenarios.

3. Custom Error Attributes

For more control over the error response, you can customize the error attributes by implementing ErrorAttributes.

Sample Code:

import org.springframework.boot.web.error.ErrorAttributeOptions
import org.springframework.boot.web.servlet.error.ErrorAttributes
import org.springframework.stereotype.Component
import org.springframework.web.context.request.WebRequest

@Component
class CustomErrorAttributes : ErrorAttributes {

    override fun getErrorAttributes(webRequest: WebRequest, options: ErrorAttributeOptions): Map<String, Any> {
        val errorAttributes = mutableMapOf<String, Any>()
        errorAttributes["status"] = 500
        errorAttributes["message"] = "Custom error message"
        return errorAttributes
    }

    override fun getError(webRequest: WebRequest): Throwable? {
        return null
    }
}

Output:

• All errors will return a response with a status of 500 and a message "Custom error message".

Advantages:

• Full control over the error response structure.
• Can be used to add additional information to error responses.

Disadvantages:

• More complex to implement.
• Requires understanding of Spring Boot's error handling internals.

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