过滤器 读取http post body

public class HttpServletRequestCheckFilter implements Filter {
    /**
     * 默认URL匹配规则
     */
    private static final Pattern URL_PATTERN = Pattern.compile("/engine/");

    private static final String PARAM_ERROR = "dsType mismatch";

    private static final long PARAM_ERROR_CODE = 403;

    private static final String SEPARATOR = "/";

    private static final String DSTYPE = "dsType";

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain)
        throws IOException, ServletException {
        if (servletRequest instanceof HttpServletRequest && servletResponse instanceof HttpServletResponse) {
            HttpServletRequest httpRequest = (HttpServletRequest) servletRequest;
            HttpServletResponse httpResponse = (HttpServletResponse) servletResponse;
            StandardHttpServletRequestEx httpServletRequestEx = new StandardHttpServletRequestEx(httpRequest);
            httpServletRequestEx.setCacheRequest(true);
            httpServletRequestEx.getInputStream();
            if (URL_PATTERN.matcher(httpServletRequestEx.getPathInfo()).find()) {
                try {
                    getDsType(httpServletRequestEx);
                } catch (Exception e) {
                    // 失败
                    BaseResponse<String> response = HttpUtil.buildResponse(PARAM_ERROR_CODE, PARAM_ERROR, String.class);
                    httpResponse.setStatus((int) ErrorCode.RETURN_PARAM_ILLEGAL);
                    httpResponse.setContentType("application/json");
                    httpResponse.getWriter().write(JsonMapper.nonNullMapper().toJson(response));
                    logger.error("check failed!exception:{}", e.getMessage());
                    return;
                }
            }
            filterChain.doFilter(httpServletRequestEx, servletResponse);
        } else {
            throw new ServletException("just supports HTTP requests");
        }
    }

    /**
     * 校验参数
     *
     * @param request 请求
     */
    private void getDsType(HttpServletRequestEx request) {
        // 获取body信息
        String body = "";
        try {
            Buffer buffer = request.getBodyBuffer();
            if (Objects.nonNull(buffer)) {
                body = buffer.toString();
            }
            String dsType = JSON.parseObject(body).get(DSTYPE).toString();
            String[] urlSplit = request.getRequestURL().toString().split(SEPARATOR);
            if (null == dsType || !urlSplit[urlSplit.length - 1].equals(dsType)) {
                throw new SignerException(PARAM_ERROR);
            }
        } catch (Exception e) {
            throw new SignerException(PARAM_ERROR);
        }
    }
}