記錄一次自己搭建項目時，使用Filter實現統一響應體時遇到的跨域問題。
問題：定義了兩個Filter過濾器，設置 corsFilter優先執行，ResponseFilter在執行后將返回體重新設置。導致跨域失敗

@Configuration
public class ApplicationAutoConfig {


    @Bean
    public FilterRegistrationBean<CorsFilter> corsFilter() {
        //1. 添加 CORS配置信息
        CorsConfiguration config = new CorsConfiguration();
        //放行哪些原始域
        config.addAllowedOrigin("http://localhost:8080");
        //是否發送 Cookie
        config.setAllowCredentials(true);
        //放行哪些請求方式
        config.addAllowedMethod("*");
        //放行哪些原始請求頭部信息
        config.addAllowedHeader("*");
        //暴露哪些頭部信息
        config.addExposedHeader("*");
        //2. 添加映射路徑
        UrlBasedCorsConfigurationSource corsConfigurationSource = new UrlBasedCorsConfigurationSource();
        corsConfigurationSource.registerCorsConfiguration("/**", config);
        //3. 返回新的CorsFilter
        FilterRegistrationBean<CorsFilter> bean = new FilterRegistrationBean(new CorsFilter(corsConfigurationSource));
        bean.setOrder(0);
        bean.addUrlPatterns("/*");
        return bean;
    }

    @Bean
    public FilterRegistrationBean<ResponseFilter> responseFilter() {
        FilterRegistrationBean<ResponseFilter> bean = new FilterRegistrationBean(new ResponseFilter());
        bean.setOrder(Integer.MAX_VALUE);
        return bean;
    }

}

由于在ReponseFilter中將request和reponse請求進行了封裝，wrapResponse()方法中，將緩存中數據取出來后，會執行重置緩存區，原來調用的是 reset() 方法，reset方法會調用父類的reset方法去把reponse中的數據也清除掉包括設置的跨域頭信息等，所以我們只需要清除掉緩存區中；將 reset()方法換成 resetBuffer() 即可

	@Override
	public void reset() {
		super.reset();
		this.content.reset();
	}
	//調用的super方法
	public void reset() {
        this.response.reset();
    }

public class ResponseFilter extends OncePerRequestFilter {

    //過濾掉swagger路徑
    private static final Set<String> ALLOWED_PATH = Collections.unmodifiableSet(
            new HashSet<>(Arrays.asList(
                    "/swagger-ui.html",
                    "/v2/api-doc",
                    "/swagger-resources",
                    "/webjars")));

    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws IOException, ServletException {
        ContentCachingRequestWrapper requestWrapper = new ContentCachingRequestWrapper(request);
        ContentCachingResponseWrapper responseWrapper = new ContentCachingResponseWrapper(response);
        filterChain.doFilter(requestWrapper, responseWrapper);
        wrapResponse(responseWrapper);
        responseWrapper.copyBodyToResponse();
    }

    /**
     * 復寫返回值信息
     *
     * @param response
     * @throws IOException
     */
    private void wrapResponse(ContentCachingResponseWrapper response) throws IOException {
        byte[] b = response.getContentAsByteArray();
        // 重置response中的body中的數據，不能使用reset()方法
        if (b.length > 0) {
            response.resetBuffer();
        }
        // 通過response的outputStream寫入新的數據
        ServletOutputStream outputStream = response.getOutputStream();
        outputStream.write(JSON.toJSONBytes(ResponseData.ok(JSON.parse(b))));
    }


    /**
     * 跳過swagger路徑
     *
     * @param request
     * @return
     */
    @Override
    protected boolean shouldNotFilter(HttpServletRequest request) {
        //過濾掉swagger路徑
        String path = request.getRequestURI().substring(request.getContextPath().length()).replaceAll("[/]+$", "");
        return ALLOWED_PATH.stream().anyMatch(path::startsWith) || StringUtils.isBlank(path);
    }
}