编写拦截器方法

public class LoginInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        HttpSession session = request.getSession();
        Object loginUser = session.getAttribute("loginUser");
        if (loginUser!=null){
            return true;
        }else{
            return false;
        }


          }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        HandlerInterceptor.super.postHandle(request, response, handler, modelAndView);
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        HandlerInterceptor.super.afterCompletion(request, response, handler, ex);
    }
}

把拦截器方法给放到我们自定义MVC的配置里面

@Configuration 把我们的配置给加载到容器里面

@Configuration
public class AdminWebConfig implements WebMvcConfigurer {
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new LoginInterceptor() )
                .addPathPatterns("/*") 
                //这是要拦截什么路径要用/* 用/**的话静态资源也会被拦截住
                .excludePathPatterns("/","/login");
                //↑这个是放行那些访问路径
    }
}

拦截器执行流程

拦截器有一下三种方法

在这里插入图片描述
顺序是

先执行
在这里插入图片描述
然后执行目标方法
然后是

最后是

如果有多个拦截器的顺序是这样的

先按顺序执行拦截器的preHandle 全部执行完执行目标方法
然后再按照反顺序执行postHandle

文件上传

  @PostMapping("/upload")
    public String upload(@RequestParam("email") String email,
                         @RequestParam("username") String username,
                         @RequestPart("headerImg") MultipartFile headerImg,
                         @RequestPart("photos") MultipartFile[] photos) throws IOException {

        log.info("上传的信息：email={}，username={}，headerImg={}，photos={}",
                email,username,headerImg.getSize(),photos.length);


        if(!headerImg.isEmpty()){
            String name = headerImg.getOriginalFilename();
            headerImg.transferTo(new File("C:\\Users\\hp\\Desktop\\test\\"+name));
        }
        if(photos.length>0){
            for (MultipartFile photo : photos) {
                if(photo!=null){
                    String name = photo.getOriginalFilename();
                    photo.transferTo(new File("C:\\Users\\hp\\Desktop\\test\\"+name));
                }


            }
        }

        return  "main";

            }