spring boot 自定义过滤器

方式一

@Configuration
public class WebConfiguration {
    @Bean
    public FilterRegistrationBean<PreFilter> preFilterRegistration() {
        FilterRegistrationBean<PreFilter> registration = new FilterRegistrationBean<>();
        registration.setFilter(new PreFilter());
        //配置过滤路径
        registration.addUrlPatterns("/*");
        //设置filter名称
        registration.setName("preFilter");
        //请求中过滤器执行的先后顺序，值越小越先执行
        registration.setOrder(Ordered.HIGHEST_PRECEDENCE);
        return registration;
    }
    @Slf4j
    public static class PreFilter extends OncePerRequestFilter {
        @Override
        protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
            log.info("into PreFilter");
            filterChain.doFilter(request, response);
        }
    }
}

方式二

如果过滤器中需要使用到依赖注入，可以使用这个方式

@Configuration
public class WebConfiguration {
    @Bean
    public FilterRegistrationBean<DelegatingFilterProxy> preFilterRegistration() {
        FilterRegistrationBean<DelegatingFilterProxy> registration = new FilterRegistrationBean<>();
        registration.setFilter(new DelegatingFilterProxy("preFilter"));
        //配置过滤路径
        registration.addUrlPatterns("/*");
        //设置filter名称
        registration.setName("preFilter");
        //请求中过滤器执行的先后顺序，值越小越先执行
        registration.setOrder(Ordered.HIGHEST_PRECEDENCE);
        return registration;
    }
    @Slf4j
    @Component("preFilter")
    public static class PreFilter extends OncePerRequestFilter {
        @Autowired
        private BizConfig bizConfig;
        @Override
        protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
            log.info("into PreFilter");
            logger.info(bizConfig.getWebHook());
            filterChain.doFilter(request, response);
        }
    }
}

FilterRegistrationBean

spring boot启动时，会加载servlet容器。这时会获取所有实现ServletContextInitializer的类，初始化并注册到ServletContext中。

DelegatingFilterProxy

DelegatingFilterProxy实现Filter，其本身就是一个过滤器，会被注册到Selvlet容器。但过滤器调用的时候，会通过targetBeanName从spring容器中获取真正的执行业务逻辑的过滤器。

DelegatingFilterProxy可以说是一个代理过滤器。