相信我，不记录核心接口的参数和响应，你会后悔的

待我称王封你为后i 2023-01-18 15:27 16阅读 0赞

*![df753c909eac47f5462f44d9a3042c70.png][]**来源：https://fredal.xin/http-body-recorder*

经常会遇到需要处理 http 请求以及响应 body 的场景。

而这里比较大的一个问题是 servle t的 requestBody 或 responseBody 流一旦被读取了就无法二次读取了。

针对这个问题，Spring 本身提供了解决方案，即：

*  [ContentCachingRequestWrapper][]
 *  [ContentCachingResponseWrapper。][ContentCachingRequestWrapper]

[我们编写一个过滤器:][ContentCachingRequestWrapper]

public abstract class HttpBodyRecorderFilter extends OncePerRequestFilter {
    
        private static final int DEFAULT_MAX_PAYLOAD_LENGTH = 1024 * 512;
    
        private int maxPayloadLength = DEFAULT_MAX_PAYLOAD_LENGTH;
    
        @Override
    
        protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
                throws ServletException, IOException {
    
            boolean isFirstRequest = !isAsyncDispatch(request);
    
            HttpServletRequest requestToUse = request;
    
            if (isFirstRequest && !(request instanceof ContentCachingRequestWrapper)
       && (request.getMethod().equals(HttpMethod.PUT.name())
                            || request.getMethod().equals(HttpMethod.POST.name()))) {
                requestToUse = new ContentCachingRequestWrapper(request);
            }
    
            HttpServletResponse responseToUse = response;
    
            if (!(response instanceof ContentCachingResponseWrapper) && (request.getMethod().equals(HttpMethod.PUT.name())
                            || request.getMethod().equals(HttpMethod.POST.name()))) {
                responseToUse = new ContentCachingResponseWrapper(response);
            }
    
            boolean hasException = false;
    
            try {
                filterChain.doFilter(requestToUse, responseToUse);
            } catch (final Exception e) {
                hasException = true;
                throw e;
            } finally {
                int code = hasException ? 500 : response.getStatus();
    
                if (!isAsyncStarted(requestToUse) && (this.codeMatched(code, AdvancedHunterConfigManager.recordCode()))) {
                    recordBody(createRequest(requestToUse), createResponse(responseToUse));
                } else {
                    writeResponseBack(responseToUse);
                }
    
            }
    
        }
    
        protected String createRequest(HttpServletRequest request) {
            String payload = "";
    
            ContentCachingRequestWrapper wrapper = WebUtils.getNativeRequest(request, ContentCachingRequestWrapper.class);
    
            if (wrapper != null) {
                byte[] buf = wrapper.getContentAsByteArray();
                payload = genPayload(payload, buf, wrapper.getCharacterEncoding());
            }
    
            return payload;
        }
    
        protected String createResponse(HttpServletResponse resp) {
            String response = "";
    
            ContentCachingResponseWrapper wrapper = WebUtils.getNativeResponse(resp, ContentCachingResponseWrapper.class);
    
            if (wrapper != null) {
                byte[] buf = wrapper.getContentAsByteArray();
    
                try {
                    wrapper.copyBodyToResponse();
                } catch (IOException e) {
                    e.printStackTrace();
                }
    
                response = genPayload(response, buf, wrapper.getCharacterEncoding());
            }
    
            return response;
    
        }
    
        protected void writeResponseBack(HttpServletResponse resp) {
            ContentCachingResponseWrapper wrapper = WebUtils.getNativeResponse(resp, ContentCachingResponseWrapper.class);
    
            if (wrapper != null) {
                try {
                    wrapper.copyBodyToResponse();
                } catch (IOException e) {
                    LOG.error("Fail to write response body back", e);
                }
            }
    
        }
    
        private String genPayload(String payload, byte[] buf, String characterEncoding) {
    
            if (buf.length > 0 && buf.length < getMaxPayloadLength()) {
                try {
                    payload = new String(buf, 0, buf.length, characterEncoding);
                } catch (UnsupportedEncodingException ex) {
                    payload = "[unknown]";
                }
            }
    
            return payload;
    
        }
    
        public int getMaxPayloadLength() {
            return maxPayloadLength;
        }
    
        private boolean codeMatched(int responseStatus, String statusCode) {
    
            if (statusCode.matches("^[0-9,]*$")) {
                String[] filteredCode = statusCode.split(",");
                return Stream.of(filteredCode).map(Integer::parseInt).collect(Collectors.toList()).contains(responseStatus);
            } else {
                return false;
            }
    
        }
    
        protected abstract void recordBody(String payload, String response);
    
        protected abstract String recordCode();
    
    }

[这样自定义一个filter继承HttpBodyRecorderFilter，重写recordBody方法就能自定义自己的处理逻辑了。][ContentCachingRequestWrapper]

[另外，recordCode方法可用于定义在请求响应码为多少的时候才会去记录body，例如可以定义为只有遇到400或500时才记录body，用于错误侦测。][ContentCachingRequestWrapper]

[过滤器的匹配规则比较简单，如果想要像springmvc那样进行匹配，我们可以使用：AntPathMatcher。][ContentCachingRequestWrapper]Spring Boot 教程推荐看这个：https://github.com/javastacks/spring-boot-best-practice

class PatternMappingFilterProxy implements Filter {
    
        private final Filter delegate;
    
        private final List<String> pathUrlPatterns = new ArrayList();
    
        private PathMatcher pathMatcher;
    
        public PatternMappingFilterProxy(Filter delegate, String... urlPatterns) {
            Assert.notNull(delegate, "A delegate Filter is required");
            this.delegate = delegate;
            int length = urlPatterns.length;
            pathMatcher = new AntPathMatcher();
            for (int index = 0; index < length; ++index) {
                String urlPattern = urlPatterns[index];
                this.pathUrlPatterns.add(urlPattern);
            }
    
        }
    
        @Override
    
        public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain)
                throws IOException, ServletException {
    
            HttpServletRequest httpRequest = (HttpServletRequest) request;
    
            String path = httpRequest.getRequestURI();
    
            if (this.matches(path)) {
                this.delegate.doFilter(request, response, filterChain);
            } else {
                filterChain.doFilter(request, response);
            }
    
        }
    
        private boolean matches(String requestPath) {
    
            for (String pattern : pathUrlPatterns) {
                if (pathMatcher.match(pattern, requestPath)) {
                    return true;
                }
            }
    
            return false;
        }
    
        @Override
        public void init(FilterConfig filterConfig) throws ServletException {
            this.delegate.init(filterConfig);
        }
    
        @Override
    
        public void destroy() {
            this.delegate.destroy();
        }
    
        public List<String> getPathUrlPatterns() {
            return pathUrlPatterns;
        }
    
        public void setPathUrlPatterns(List<String> urlPatterns) {
            pathUrlPatterns.clear();
            pathUrlPatterns.addAll(urlPatterns);
        }
    
    }

[这样子，PatternMappingFilterProxy装饰了真正的HttpBodyRecorderFilter，支持传入urlPatterns，从而实现像springmvc那样的ant style的匹配。例如对于以下接口：][ContentCachingRequestWrapper]

@PostMapping("/test/{id}")
    public Object test(@PathVariable(value =  "id",required =  true)  final Integer index)  {
    
     //do something
    
    }

可以设置urlPattern为`/test/{id:[0-9]+}`。

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[df753c909eac47f5462f44d9a3042c70.png]: /images/20221021/fd2c03dbbee04ade97a585b8e4eb441f.png
[ContentCachingRequestWrapper]: http://mp.weixin.qq.com/s?__biz=MzI3ODcxMzQzMw%3D%3D&chksm=eb50e6e2dc276ff426feacc5f9d28fda5e3ab7755c1b2eca1879b1a5d472f47b9726acc7c836&idx=3&mid=2247525332&scene=21&sn=b2ab5ff3febed75999f07ca1832ec3b5#wechat_redirect