Spring 3 MVC @Controller 与 AOP 拦截器

在Spring框架中，@Controller注解用于标识一个类是控制器，处理用户的请求并返回相应的结果。与之配合的是AOP（面向切面编程）拦截器，它可以在方法执行前、执行后或异常抛出时拦截并执行一些额外的逻辑。本文将围绕这两个主题展开，介绍如何在Spring 3 MVC中使用@Controller注解和AOP拦截器。

java
@Controller
public class HelloController {
    @RequestMapping("/hello")
    public String hello() {
        return "hello";
    }
}

java
public class LoggingInterceptor extends HandlerInterceptorAdapter {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("Before handling the request");
        return true;
    }
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("After handling the request");
    }
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("After completing the request");
    }
}

xml
    

java
@Controller
public class UserController {
    @Autowired
    private UserService userService;
    @RequestMapping(value = "/user/{id}", method = RequestMethod.GET)
    public String getUser(@PathVariable("id") int id, ModelMap model) {
        User user = userService.getUserById(id);
        model.addAttribute("user", user);
        return "user";
    }
}