Spring Boot Exception Handling

Implementing Global Exception Handling:

• Use @ControllerAdvice and @ExceptionHandler to handle exceptions globally.

Example: Custom Exception for Resource Not Found

1. Create a ResourceNotFoundException Class:

   java

    package com.example.demo;
   
    public class ResourceNotFoundException extends RuntimeException {
        public ResourceNotFoundException(String message) {
            super(message);
        }
    }
   

2. Handle Exception in Controller:

   java

    package com.example.demo;
   
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.http.HttpStatus;
    import org.springframework.http.ResponseEntity;
    import org.springframework.web.bind.annotation.*;
   
    @RestController
    @RequestMapping("/products")
    public class ProductController {
   
        @Autowired
        private ProductRepository productRepository;
   
        @GetMapping("/{id}")
        public ResponseEntity<Product> getProduct(@PathVariable Long id) {
            Product product = productRepository.findById(id)
                .orElseThrow(() -> new ResourceNotFoundException("Product not found"));
            return ResponseEntity.ok(product);
        }
   
        // Other CRUD methods...
    }
   

3. Create a Global Exception Handler:

   java

    package com.example.demo;
   
    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.bind.annotation.ResponseStatus;
   
    @ControllerAdvice
    public class GlobalExceptionHandler {
   
        @ExceptionHandler(ResourceNotFoundException.class)
        @ResponseStatus(HttpStatus.NOT_FOUND)
        public ResponseEntity<String> handleResourceNotFoundException(ResourceNotFoundException ex) {
            return new ResponseEntity<>(ex.getMessage(), HttpStatus.NOT_FOUND);
        }
   
        // Other exception handlers...
    }
   

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