三十、请求拦截器

我们可以新建一个拦截器，然后在mvc中添加这个拦截器，就可以达到拦截请求的功能了。

public class UserTokenInterceptor implements HandlerInterceptor {

    /**
     * 拦截请求，在访问controller之前
     * @param request
     * @param response
     * @param handler
     * @return
     * @throws Exception
     */
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        /**
         * false 请求被拦截，被驳回，验证出现问题
         * true 请求在经过验证校验以后，是ok的，是可以放行的
         */
        return false;
    }

    /**
     * 请求访问controller之后，渲染视图之前
     * @param request
     * @param response
     * @param handler
     * @param modelAndView
     * @throws Exception
     */
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {

    }

    /**
     * 请求访问controller之后，渲染视图之后
     * @param request
     * @param response
     * @param handler
     * @throws Exception
     */
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

    }
}

    // 实现静态资源的映射
    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/**")
                .addResourceLocations("classpath:/META-INF/resources/")  // 映射swagger2
                .addResourceLocations("file:/workspaces/images/");  // 映射本地静态资源
    }

    @Bean
    public RestTemplate restTemplate(RestTemplateBuilder builder) {
        return builder.build();
    }

    @Bean
    public UserTokenInterceptor userTokenInterceptor() {
        return new UserTokenInterceptor();
    }


    @Override
    public void addInterceptors(InterceptorRegistry registry){
        registry.addInterceptor(userTokenInterceptor())
                .addPathPatterns("/hello");
        WebMvcConfigurer.super.addInterceptors(registry);
    }

如果不需要拦截，可以在拦截器里面做好配置

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