5. Spring MVC 4.1-拦截器-白红宇

5. Spring MVC 4.1-拦截器

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发布时间：2019-05-25

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5.1 拦截器

拦截器实现了对每一个请求处理之前和之后进行相关的处理,类似于Servlet的filter;

可以实现HandlerInterceptor接口或者继承HandlerInterceptorAdapter类;

继承HandlerInterceptorAdapter类,因为使用接口要实现接口的所有方法;

5.2 示例

新建拦截器

package com.wisely.interceptors;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.springframework.stereotype.Service;import org.springframework.web.servlet.ModelAndView;import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;public class DemoInteceptor extends HandlerInterceptorAdapter {    @Override    public boolean preHandle(HttpServletRequest request,            HttpServletResponse response, Object handler) throws Exception {        System.out.println("request开始前");        long startTime = System.currentTimeMillis();        request.setAttribute("startTime", startTime);        return true;    }    @Override    public void postHandle(HttpServletRequest request,            HttpServletResponse response, Object handler,            ModelAndView modelAndView) throws Exception {        System.out.println("request结束后");        long startTime = (Long) request.getAttribute("startTime");        request.removeAttribute("startTime");        long endTime = System.currentTimeMillis();        request.setAttribute("handlingTime", endTime - startTime);    }}

修改配置,注册拦截器 
   package com.wisely;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.ComponentScan;import org.springframework.context.annotation.Configuration;import org.springframework.web.servlet.config.annotation.EnableWebMvc;import org.springframework.web.servlet.config.annotation.InterceptorRegistry;import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;import org.springframework.web.servlet.view.JstlView;import org.springframework.web.servlet.view.UrlBasedViewResolver;import com.wisely.interceptors.DemoInteceptor;@Configuration@ComponentScan("com.wisely")@EnableWebMvcpublic class DemoMVCConfig extends WebMvcConfigurerAdapter {    @Bean    public UrlBasedViewResolver viewResolver(){        UrlBasedViewResolver resolver = new UrlBasedViewResolver();        resolver.setPrefix("/WEB-INF/views/");        resolver.setSuffix(".jsp");        resolver.setViewClass(JstlView.class);        return resolver;    }    //注册拦截器    @Override    public void addInterceptors(InterceptorRegistry registry) {    registry.addInterceptor(demoInteceptor());    }    //自定义拦截器    @Bean    public DemoInteceptor demoInteceptor(){        return new DemoInteceptor();    }}    
   
    在index.jsp添加代码接受拦截器里放置的handlingTime 
   <%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%>
     Insert title hereindex.jsp  is herevalue from inteceptor 处理耗时:${handlingTime}ms 输出结果：