Ang reliability ay isang asset ng mga malaking financial at analytics platform. Kapag re-designing ng isang enterprise platform, natuklasan namin na ang pangunahing bagay na kung saan ang mga customer ay hindi masaya ay hindi ang pagganap o ang user interface; ito ay mga bug na hindi na fixed na hinihikayat ang mga proseso. Sa Spring Boot o mga katulad na pattern sa iba pang frameworks, panatilihin na ang mga sistema ay gumagana tulad ng inaasahan kapag nasa ilalim ng stress. @ControllerAdvice Why This Matters Kapag bumalik sa UP, i'll start building a new me. , makakakuha ka ng mabilis ang problema na ito: Spring Boot “ ” How do I handle errors neatly without writing repetitive try-catch blocks everywhere? Imagine na ang Lahat ng mga ito ay maaaring maging isang a Invalid na input, o isang walang resource. Sa halip ng pagbabago ng mga traces, gusto mo . 50+ endpoints Ang Null Pointer Exception consistent, meaningful, and client-friendly error responses Ito ay kung saan Nag-centralize ang lahat ng error handling sa isang lugar. Tingnan ang Paggawa ng ito step by step, na may isang real-world na halimbawa. @ControllerAdvice how Use Case — User Management REST API Kami ay lumikha ng isang Ito ang suporta: simple User API 
 
 
 
 
 
 Fetching users 
 
 Creating users 
 
 
 Simulating failures for testing Our goal → build a   that returns clean JSON responses. unified global error-handling layer Step 1: Project Setup Dependencies (Maven): <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-validation</artifactId>
    </dependency>
 This brings in web + validation support. Then create your main app: @SpringBootApplication
public class ExceptionHandlerDemoApplication {
    public static void main(String[] args) {
        SpringApplication.run(ExceptionHandlerDemoApplication.class, args);
    }
}
 Step 2: Define the Entity — User.java @Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
    private int id;
    @NotBlank(message = "Name cannot be blank")
    private String name;
    @Min(value = 18, message = "Age must be at least 18")
    private int age;
}
 · Bakit: ** Ipinapakita namin ang mga simpleng pag-validasyon upang ang Spring ay maaaring i-activate ang Non-valid Exception ng Argument ng Method automatically kapag ang input ay hindi katangian. Step 3: Custom Exception for Missing Data public class ResourceNotFoundException extends RuntimeException {
    public ResourceNotFoundException(String message) {
        super(message);
    }
}
public class InvalidRequestException extends RuntimeException {
    public InvalidRequestException(String message) {
        super(message);
    }
}
 · Bakit: * I-represent ang isang "user not found" situation cleanly sa halip ng mga generic exception. Step 4: Build the Controller @RestController
@RequestMapping("/api/users")
public class UserController {
    // Simple GET that throws ResourceNotFoundException for id > 100
    @GetMapping("/{id}")
    public String getUser(@PathVariable("id") @Min(1) Integer id) {
        if (id > 100) {
            throw new ResourceNotFoundException("User with id " + id + " not found");
        }
        return "User-" + id;
    }
    // Create user example to demonstrate validation
    public static record CreateUserRequest(
            @NotBlank(message = "name is required") String name,
            @Min(value = 18, message = "age must be >= 18") int age) {}
    @PostMapping
    @ResponseStatus(HttpStatus.CREATED)
    public String createUser(@RequestBody @Valid CreateUserRequest body) {
        if ("bad".equalsIgnoreCase(body.name())) {
            throw new InvalidRequestException("Name 'bad' is not allowed");
        }
        return "created:" + body.name();
    }
    // Endpoint to force a server error for demo
    @GetMapping("/boom")
    public void boom() {
        throw new IllegalStateException("simulated server error");
    }
}
 · Bakit: ** Kami ay lumikha ng mga realisteng mga scenarios - hindi natagpuan, mga error ng pag-validasyon, at mga error ng runtime - na ang aming global manager ay mag-manage. Step 5: Create a Standard Error Model @Data
@AllArgsConstructor
@NoArgsConstructor
public class ErrorResponse {
    private OffsetDateTime timestamp;
    private int status;
    private String error;
    private String message;
    private String path;
    private List<FieldError> fieldErrors;}
 · Bakit: ** Ang lahat ng APIs ay dapat ibalik ang mga error sa parehong strukturong - ito ay mapabuti ang monitoring at pag-debug sa produksyon. Step 6: Implement @ControllerAdvice (Global Handler) @ControllerAdvice
public class GlobalExceptionHandler {
    private final Logger log = LoggerFactory.getLogger(GlobalExceptionHandler.class);
    // Handle custom validation exceptions
    @ExceptionHandler(InvalidRequestException.class)
    public ResponseEntity<ErrorResponse> handleInvalidRequest(InvalidRequestException ex, HttpServletRequest req) {
        log.debug("InvalidRequestException: {}", ex.getMessage());
        ErrorResponse body = new ErrorResponse(OffsetDateTime.now(), HttpStatus.BAD_REQUEST.value(),
                HttpStatus.BAD_REQUEST.getReasonPhrase(), ex.getMessage(), req.getRequestURI());
        return ResponseEntity.status(HttpStatus.BAD_REQUEST).body(body);
    }
    // Resource not found -> 404
    @ExceptionHandler(ResourceNotFoundException.class)
    public ResponseEntity<ErrorResponse> handleNotFound(ResourceNotFoundException ex, HttpServletRequest req) {
        log.debug("ResourceNotFoundException: {}", ex.getMessage());
        ErrorResponse body = new ErrorResponse(OffsetDateTime.now(), HttpStatus.NOT_FOUND.value(),
                HttpStatus.NOT_FOUND.getReasonPhrase(), ex.getMessage(), req.getRequestURI());
        return ResponseEntity.status(HttpStatus.NOT_FOUND).body(body);
    }
    // Validation errors from @Valid on request bodies
    @ExceptionHandler(MethodArgumentNotValidException.class)
    public ResponseEntity<ErrorResponse> handleValidation(MethodArgumentNotValidException ex, HttpServletRequest req) {
        log.debug("Validation failed: {}", ex.getMessage());
        List<ErrorResponse.FieldError> fieldErrors = ex.getBindingResult().getFieldErrors().stream()
                .map(fe -> new ErrorResponse.FieldError(fe.getField(), fe.getRejectedValue(), fe.getDefaultMessage()))
                .collect(Collectors.toList());
        ErrorResponse body = new ErrorResponse(OffsetDateTime.now(), HttpStatus.BAD_REQUEST.value(),
                HttpStatus.BAD_REQUEST.getReasonPhrase(), "Validation failed", req.getRequestURI());
        body.setFieldErrors(fieldErrors);
        return ResponseEntity.badRequest().body(body);
    }
    // Type mismatch for method args (?id=abc)
    @ExceptionHandler(MethodArgumentTypeMismatchException.class)
    public ResponseEntity<ErrorResponse> handleTypeMismatch(MethodArgumentTypeMismatchException ex, HttpServletRequest req) {
        log.debug("Type mismatch: {}", ex.getMessage());
        ErrorResponse body = new ErrorResponse(OffsetDateTime.now(), HttpStatus.BAD_REQUEST.value(),
                HttpStatus.BAD_REQUEST.getReasonPhrase(), ex.getMessage(), req.getRequestURI());
        return ResponseEntity.badRequest().body(body);
    }
    // No handler found (404 for unmatched endpoints)
    @ExceptionHandler(NoHandlerFoundException.class)
    public ResponseEntity<ErrorResponse> handleNoHandler(NoHandlerFoundException ex, HttpServletRequest req) {
        log.debug("NoHandlerFound: {} {}", ex.getHttpMethod(), ex.getRequestURL());
        ErrorResponse body = new ErrorResponse(OffsetDateTime.now(), HttpStatus.NOT_FOUND.value(),
                HttpStatus.NOT_FOUND.getReasonPhrase(), "Endpoint not found", req.getRequestURL().toString());
        return ResponseEntity.status(HttpStatus.NOT_FOUND).body(body);
    }
    // Generic fallback
    @ExceptionHandler(Exception.class)
    public ResponseEntity<ErrorResponse> handleAll(Exception ex, HttpServletRequest req) {
        log.error("Unhandled exception: ", ex);
        ErrorResponse body = new ErrorResponse(OffsetDateTime.now(), HttpStatus.INTERNAL_SERVER_ERROR.value(),
                HttpStatus.INTERNAL_SERVER_ERROR.getReasonPhrase(), "An internal error occurred", req.getRequestURI());
        return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body(body);
    }
}
 Why: 
 
 
 
 @ControllerAdvice → Ginawa ito sa buong mundo sa lahat ng mga controller. @ExceptionHandler → I-catch ang anumang mga uri ng exception. Ang buildResponse() helper ay matatagpuan ang code DRY at clean. Step 7: Test Scenarios   GET /api/users/1 Code ng Response: 200 -Sukses * ang * ang GET /api/users/999 404 Resource Not Found: Ang resource ay hindi natagpuan * ang * ang Validation Error Mga pahinang tumuturo sa POST /api/users {"name":"", "age": 15} Response: * ang * ang Unexpected Error Mga pahinang tumuturo sa /api/user/boom * ang * ang Why This Approach Works in Real Projects 
 
 
 
 
 
 
 
 
 
 Problem 
 Solution 
 
 
 
 Too many try-catch blocks 
 Centralized handling with @ControllerAdvice 
 
 
 
 Inconsistent responses 
 Unified ErrorResponse structure 
 
 
 
 Hard to debug 
 Standardized messages with timestamps and paths 
 
 
 
 Client confusion 
 Clear, meaningful messages for each failure type Mayroong maraming try-catch blocks Centralized paghahatid sa pamamagitan ng @ControllerAdvice Mga Incoherent Response Unified ErrorResponse Structure sa pamamagitan ng Magkakaroon ng debug Mga standardized na mensahe na may timestamp at path Mga Customer Confusion Clear, meaningful na mensahe para sa bawat uri ng error Real-World Usage Scenarios 
 
 
 
 
 Banking APIs: I-siguraduhin na ang mga error ng pag-validasyon (tulad ng invalid na numero ng account) ay hindi nag-crash ang serbisyo. E-commerce: I-manage ang mga error ng produkto na hindi natagpuan o pagbabayad na gracefully. Data Microservices: Ibalik ang mga estruktural na mensahe kapag ang input data ay hindi na validasyon. API Gateway: Consistent responses sa pamamagitan ng maraming microservices. Final Thoughts Sa pamamagitan ng paghahambing ng @ControllerAdvice, @ExceptionHandler, at isang simpleng Error Response modelo, makakuha ka ng: 
 
 
 
 Clean ang code Mga pahinang tumuturo API Pagbabago sa produksyon Ito ay isa sa mga simpleng ngunit napaka-powerful na mga pattern ng disenyo sa Spring Boot development.

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Pag-disenyo ng Reliable API Systems: Exception Handling sa Spring Boot's Controller

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