springMVC interceptor

HandlerInterceptor

public class HandlerInterceptorDemo implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        return false;
    }

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

    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

    }
}

WebRequestInterceptor

public class WebRequestInterceptorDemo implements WebRequestInterceptor {

    @Override
    public void preHandle(WebRequest webRequest) throws Exception {

    }

    @Override
    public void postHandle(WebRequest webRequest, ModelMap modelMap) throws Exception {

    }

    @Override
    public void afterCompletion(WebRequest webRequest, Exception e) throws Exception {

    }
}

说明：interceptor是在请求在适配之后，对具体的handler方法前后的业务处理。
interceptor并不会拦截到所有request，它只有在handlerMapping找到对应的映射之后才会起作用。