关于java:如何优雅记录-http-请求-响应数据

常常会遇到须要解决 http 申请以及响应 body 的场景。

而这里比拟大的一个问题是 servle t 的 requestBody 或 responseBody 流一旦被读取了就无奈二次读取了。

针对这个问题，Spring 自身提供了解决方案，即：

• ContentCachingRequestWrapper
• ContentCachingResponseWrapper。

咱们编写一个过滤器:

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 办法就能自定义本人的解决逻辑了。

另外，recordCode 办法可用于定义在申请响应码为多少的时候才会去记录 body，例如能够定义为只有遇到 400 或 500 时才记录 body，用于谬误侦测。

过滤器的匹配规定比较简单，如果想要像 springmvc 那样进行匹配，咱们能够应用：AntPathMatcher。

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 装璜了真正的 HttpBodyRecorderFilter，反对传入 urlPatterns，从而实现像 springmvc 那样的 ant style 的匹配。例如对于以下接口：

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

能够设置 urlPattern 为 /test/{id:[0-9]+}。

作者：fredalxin
地址：https://fredal.xin/http-body-…