Spring Boot - Service Class Example for Displaying Response Codes and Custom Error Codes

Spring Boot - Service Class Example for Displaying Response Codes and Custom Error Codes

In a typical Spring Boot application, a Service class is responsible for the business logic while the Controller handles HTTP requests and responses. Here, I will provide an example of a Service class that displays response codes and custom error codes.

Let's assume we're building an application that manages user profiles.

1. Define custom error codes:

Create an enum for your custom error codes:

public enum ErrorCode { USER_NOT_FOUND("ERR001", "User not found"), INVALID_INPUT("ERR002", "Invalid input provided"); private final String code; private final String description; ErrorCode(String code, String description) { this.code = code; this.description = description; } public String getCode() { return code; } public String getDescription() { return description; } }

2. Create a custom exception:

public class CustomException extends RuntimeException { private final ErrorCode errorCode; public CustomException(ErrorCode errorCode) { super(errorCode.getDescription()); this.errorCode = errorCode; } public ErrorCode getErrorCode() { return errorCode; } }

3. Service class:

Let's assume we have a User entity and a UserRepository that extends JpaRepository.

Here's a Service class:

import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; @Service public class UserService { @Autowired private UserRepository userRepository; public User getUserById(Long id) { return userRepository.findById(id).orElseThrow(() -> new CustomException(ErrorCode.USER_NOT_FOUND)); } }

4. Handle the custom exception:

You can use Spring's @ControllerAdvice and @ExceptionHandler to handle exceptions globally.

import org.springframework.http.HttpStatus; import org.springframework.http.ResponseEntity; import org.springframework.web.bind.annotation.ControllerAdvice; import org.springframework.web.bind.annotation.ExceptionHandler; @ControllerAdvice public class GlobalExceptionHandler { @ExceptionHandler(CustomException.class) public ResponseEntity<?> handleCustomException(CustomException ex) { // Build a custom error response, here just using a simple string for demonstration String response = ex.getErrorCode().getCode() + ": " + ex.getMessage(); return new ResponseEntity<>(response, HttpStatus.BAD_REQUEST); // You can customize the HTTP status based on the error. } }

5. Using the Service in a Controller:

import org.springframework.beans.factory.annotation.Autowired; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.RestController; @RestController @RequestMapping("/users") public class UserController { @Autowired private UserService userService; @GetMapping("/{id}") public User getUser(@PathVariable Long id) { return userService.getUserById(id); } }

Now, when you try to fetch a user that doesn't exist (e.g., /users/9999), the service will throw a CustomException with an appropriate error code. The global exception handler will then catch this exception and send a response with the custom error code and its description.

Examples

  1. Handling HTTP status codes in Spring Boot service:

    • Description: Spring Boot provides a way to handle and set HTTP status codes in the service layer. This is useful for indicating the success or failure of an operation.
    • Code:
      // Example handling HTTP status codes in Spring Boot service @Service public class MyService { public ResponseEntity<String> processRequest() { // Business logic if (successCondition) { return ResponseEntity.ok("Operation successful"); } else { return ResponseEntity.status(HttpStatus.BAD_REQUEST).body("Operation failed"); } } }

  2. Custom error messages in Spring Boot service class:

    • Description: Customize error messages returned by the service layer to provide meaningful information to clients.
    • Code:
      // Example custom error messages in Spring Boot service @Service public class MyService { public String processRequest() { // Business logic if (errorCondition) { throw new RuntimeException("Custom error message"); } return "Operation successful"; } }

  3. Mapping custom error codes in Spring Boot service:

    • Description: Map custom error codes to specific exceptions or conditions in the service layer to differentiate between various error scenarios.
    • Code:
      // Example mapping custom error codes in Spring Boot service @Service public class MyService { public String processRequest() { // Business logic if (errorCondition) { throw new CustomException("Custom error code: 1001"); } return "Operation successful"; } }

  4. Displaying response codes in Spring Boot REST services:

    • Description: Display response codes in Spring Boot REST services to communicate the outcome of the operation to clients.
    • Code:
      // Example displaying response codes in Spring Boot REST service @RestController public class MyController { @Autowired private MyService myService; @GetMapping("/process") public ResponseEntity<String> processRequest() { return myService.processRequest(); } }

  5. Error handling and exception management in Spring Boot service:

    • Description: Implement error handling and exception management to gracefully handle unexpected errors and provide appropriate responses.
    • Code:
      // Example error handling in Spring Boot service @Service public class MyService { public String processRequest() { try { // Business logic if (errorCondition) { throw new CustomException("Custom error"); } return "Operation successful"; } catch (CustomException e) { // Log the exception or handle it return "Error: " + e.getMessage(); } } }

  6. Configuring global error handling in Spring Boot service class:

    • Description: Configure global error handling in the service class to centralize error management and apply consistent handling across the application.
    • Code:
      // Example global error handling in Spring Boot service @Service @ControllerAdvice public class GlobalExceptionHandler { @ExceptionHandler(CustomException.class) public ResponseEntity<String> handleCustomException(CustomException ex) { return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body("Global Error: " + ex.getMessage()); } }

  7. Logging response codes and errors in Spring Boot:

    • Description: Use logging to capture response codes and errors in Spring Boot services for monitoring and debugging purposes.
    • Code:
      // Example logging response codes and errors in Spring Boot service @Service public class MyService { private static final Logger logger = LoggerFactory.getLogger(MyService.class); public String processRequest() { try { // Business logic if (errorCondition) { throw new CustomException("Custom error"); } return "Operation successful"; } catch (CustomException e) { // Log the exception logger.error("Error in processRequest(): {}", e.getMessage()); return "Error: " + e.getMessage(); } } }

  8. Defining and using custom error classes in Spring Boot:

    • Description: Define custom error classes to encapsulate error information and create a structured approach to handling errors in the service layer.
    • Code:
      // Example defining and using custom error classes in Spring Boot service public class CustomException extends RuntimeException { public CustomException(String message) { super(message); } } @Service public class MyService { public String processRequest() { // Business logic if (errorCondition) { throw new CustomException("Custom error"); } return "Operation successful"; } }

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