Spring MVC HandlerInterceptor拦截器

HandlerInterceptor 用于拦截控制器方法的执行，在请求到达控制器前后及视图渲染后插入自定义处理逻辑。

接口定义

public interface HandlerInterceptor {
    default boolean preHandle(HttpServletRequest request, HttpServletResponse response,
                             Object handler) throws Exception {
        return true;
    }

    default void postHandle(HttpServletRequest request, HttpServletResponse response,
                            Object handler, ModelAndView modelAndView) throws Exception {
    }

    default void afterCompletion(HttpServletRequest request, HttpServletResponse response,
                                 Object handler, Exception ex) throws Exception {
    }
}

三个回调方法

自定义拦截器实现

@Component
public class LoginInterceptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response,
                             Object handler) throws Exception {
        HttpSession session = request.getSession();
        Object user = session.getAttribute("user");
        if (user == null) {
            response.sendRedirect("/login");
            return false;
        }
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response,
                           Object handler, ModelAndView modelAndView) throws Exception {
        // 可修改ModelAndView
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response,
                                 Object handler, Exception ex) throws Exception {
        // 资源清理、异常日志记录
    }
}

注册拦截器

@Configuration
public class WebConfig implements WebMvcConfigurer {

    @Autowired
    private LoginInterceptor loginInterceptor;

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(loginInterceptor)
                .addPathPatterns("/**")
                .excludePathPatterns("/login", "/static/**");
    }
}

执行顺序

多个拦截器按注册顺序执行：

• preHandle：正序执行
• postHandle、afterCompletion：逆序执行

拦截器只能拦截控制器方法，无法拦截静态资源请求（需在注册时排除）。

要点总结

• preHandle 返回 false 可中断请求链
• 拦截器通过 WebMvcConfigurer 注册
• 通过 addPathPatterns/excludePathPatterns 配置拦截路径
• 多个拦截器按注册顺序形成责任链