Java优学网Spring框架核心概念讲解：从传统到现代，轻松掌握依赖注入与AOP

// 传统方式 public class UserService {

private UserRepository userRepository = new UserRepository();

}

// Spring方式 @Component public class UserService {

private final UserRepository userRepository;

public UserService(UserRepository userRepository) {
    this.userRepository = userRepository;
}

}

@Aspect @Component public class LoggingAspect {

@Before("execution(* com.example.service.*.*(..))")
public void logMethodCall(JoinPoint joinPoint) {
    System.out.println("调用方法: " + joinPoint.getSignature().getName());
}

}

@Controller @RequestMapping("/products") public class ProductController {

@Autowired
private ProductService productService;

@GetMapping
public String listProducts(Model model) {
    model.addAttribute("products", productService.findAll());
    return "products/list";
}

@PostMapping
public String createProduct(@Valid Product product, BindingResult result) {
    if (result.hasErrors()) {
        return "products/new";
    }
    productService.save(product);
    return "redirect:/products";
}

}