Java全面深入探究SpringBoot拦截器与文件上传

//必须实现HandlerInterceptor这个接口
public class LoginInterceptor implements HandlerInterceptor {
    /*
    * 目标方法执行以前
    * */
    @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;
        }
        request.setAttribute("msg" ,"请登录！");
//        response.sendRedirect("/");
        request.getRequestDispatcher("/").forward(request,response);
        return  false;
    }
    //目标方法执行以后
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
    }
    /**
     * 页面渲染以后
     * @param request
     * @param response
     * @param handler
     * @param ex
     * @throws Exception
     */
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        HandlerInterceptor.super.afterCompletion(request, response, handler, ex);
    }
}

@Configuration
public class AdminWebConfig implements WebMvcConfigurer {
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new LoginInterceptor())
                .addPathPatterns("/**") //静态路径也会被拦截
                .excludePathPatterns("/","/login","/css/**","/fonts/**" ,"/images/**","/js/**");
    }
}

<form method="post" action="/upload" enctype="multipart/form-data">
    <input type="file" name="file"><br>
    <input type="submit" value="提交">
</form>

@Controller
public class FileController {
    @GetMapping("/updateFile")
    public String FileUp(){
        return "FileUp";
    }  
@PostMapping("/upload") // //new annotation since 4.3
    public String singleFileUpload(@RequestParam("file") MultipartFile file,
                                   RedirectAttributes redirectAttributes) {
        if (file.isEmpty()) {
            redirectAttributes.addFlashAttribute("message", "Please select a file to upload");
            return "redirect:uploadStatus";
        }
        try {
            // Get the file and save it somewhere
            byte[] bytes = file.getBytes();
            Path path = Paths.get( file.getOriginalFilename());
            Files.write(path, bytes);
            redirectAttributes.addFlashAttribute("message",
                    "You successfully uploaded '" + file.getOriginalFilename() + "'");
        } catch (IOException e) {
            e.printStackTrace();
        }
        return "redirect:/main.html";
    }
}