SpringBoot中9个内置过滤器用法的完整指南

@Bean
public FilterRegistrationBean<CharacterEncodingFilter> characterEncodingFilter() {
    CharacterEncodingFilter filter = new CharacterEncodingFilter();
    filter.setEncoding("UTF-8");              // ① 指定编码
    filter.setForceEncoding(true);            // ② 强制覆盖已有编码
    FilterRegistrationBean<CharacterEncodingFilter> bean = new FilterRegistrationBean<>(filter);
    bean.addUrlPatterns("/*");                // ③ 拦截所有请求
    bean.setOrder(Ordered.HIGHEST_PRECEDENCE);// ④ 最先执行，防止其他过滤器捣蛋
    return bean;
}

<form action="/books/7" method="post">
  <input type="hidden" name="_method" value="DELETE"/>
  <button type="submit">删除图书</button>
</form>

@PutMapping("/users/{id}")
public String updateUser(@PathVariable Long id, UserForm form) {
    // 表单字段自动封装进 UserForm
    userService.update(id, form);
    return "redirect:/users";
}

@Service
public class ClientInfoService {
    public String whoami() {
        ServletRequestAttributes attrs = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
        HttpServletRequest req = attrs.getRequest();
        return String.format("IP: %s, UA: %s",
                             req.getRemoteAddr(),
                             req.getHeader("User-Agent"));
    }
}

@Bean
public CorsFilter corsFilter() {
    CorsConfiguration cfg = new CorsConfiguration();
    cfg.setAllowCredentials(true);                // ① 允许携带 Cookie
    cfg.addAllowedOrigin("https://spa.xxx.com");  // ② 白名单域名
    cfg.addAllowedHeader("*");                    // ③ 任意请求头
    cfg.addAllowedMethod("*");                    // ④ 任意方法
    UrlBasedCorsConfigurationSource src = new UrlBasedCorsConfigurationSource();
    src.registerCorsConfiguration("/api/**", cfg);
    return new CorsFilter(src);
}

@Bean
public FilterRegistrationBean<ShallowEtagHeaderFilter> etag() {
    FilterRegistrationBean<ShallowEtagHeaderFilter> bean = new FilterRegistrationBean<>();
    bean.setFilter(new ShallowEtagHeaderFilter());
    bean.addUrlPatterns("/static/*", "/api/report/*");
    return bean;
}

@Bean
public FilterRegistrationBean<ForwardedHeaderFilter> forwarded() {
    FilterRegistrationBean<ForwardedHeaderFilter> bean = new FilterRegistrationBean<>();
    bean.setFilter(new ForwardedHeaderFilter());
    bean.setOrder(Ordered.HIGHEST_PRECEDENCE);   // 越早越好
    return bean;
}

@Configuration
public class WebCfg implements WebMvcConfigurer {
    @Bean
    public ResourceUrlEncodingFilter resourceUrlEncodingFilter() {
        return new ResourceUrlEncodingFilter();
    }

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/static/**")
                .addResourceLocations("classpath:/static/")
                .setCacheControl(CacheControl.maxAge(365, TimeUnit.DAYS))
                .resourceChain(true)
                .addResolver(new VersionResourceResolver()
                        .addContentVersionStrategy("/**")); // ① 哈希指纹
    }
}

<link rel="stylesheet" th:href="@{/static/css/app.css}" rel="external nofollow"  />
<!-- 实际输出：/static/css/app-8a9b2c3.css -->