Spring Cloud Gateway 获取请求体（Request Body）的多种方法

一、直接在全局拦截器中获取，伪代码如下

private String resolveBodyFromRequest(ServerHttpRequest serverHttpRequest){ Flux<DataBuffer> body = serverHttpRequest.getBody(); AtomicReference<String> bodyRef = new AtomicReference<>(); body.subscribe(buffer -> { CharBuffer charBuffer = StandardCharsets.UTF_8.decode(buffer.asByteBuffer()); DataBufferUtils.release(buffer); bodyRef.set(charBuffer.toString()); }); return bodyRef.get(); }

存在的缺陷：其他拦截器无法再通过该方式获取请求体（因为请求体已被消费），并且会抛出异常

Only one connection receive subscriber allowed.Caused by: java.lang.IllegalStateException: Only one connection receive subscriber allowed.

异常原因：实际上spring-cloud-gateway反向代理的原理是，首先读取原请求的数据，然后构造一个新的请求，将原请求的数据封装到新的请求中，然后再转发出去。然而我们在他封装之前读取了一次request body，而request body只能读取一次。因此就出现了上面的错误。

再者受版本限制

这种方法在spring-boot-starter-parent 2.0.6.RELEASE + Spring Cloud Finchley.SR2 body 中生效，

但是在spring-boot-starter-parent 2.1.0.RELEASE + Spring Cloud Greenwich.M3 body 中不生效，总是为空

二、先在全局过滤器中获取，然后再把request重新包装，继续向下传递传递

@Override public GatewayFilter apply(NameValueConfig nameValueConfig) { return (exchange, chain) -> { URI uri = exchange.getRequest().getURI(); URI ex = UriComponentsBuilder.fromUri(uri).build(true).toUri(); ServerHttpRequest request = exchange.getRequest().mutate().uri(ex).build(); if('POST'.equalsIgnoreCase(request.getMethodValue())){//判断是否为POST请求 Flux<DataBuffer> body = request.getBody(); AtomicReference<String> bodyRef = new AtomicReference<>(); body.subscribe(dataBuffer -> { CharBuffer charBuffer = StandardCharsets.UTF_8.decode(dataBuffer.asByteBuffer()); DataBufferUtils.release(dataBuffer); bodyRef.set(charBuffer.toString()); });//读取request body到缓存 String bodyStr = bodyRef.get();//获取request body System.out.println(bodyStr);//这里是我们需要做的操作 DataBuffer bodyDataBuffer = stringBuffer(bodyStr); Flux<DataBuffer> bodyFlux = Flux.just(bodyDataBuffer); request = new ServerHttpRequestDecorator(request){ @Override public Flux<DataBuffer> getBody() { return bodyFlux; } };//封装我们的request } return chain.filter(exchange.mutate().request(request).build()); }; }　protected DataBuffer stringBuffer(String value) { byte[] bytes = value.getBytes(StandardCharsets.UTF_8); NettyDataBufferFactory nettyDataBufferFactory = new NettyDataBufferFactory(ByteBufAllocator.DEFAULT); DataBuffer buffer = nettyDataBufferFactory.allocateBuffer(bytes.length); buffer.write(bytes); return buffer; }

该方案的缺陷：request body获取不完整（因为异步原因），只能获取1024B的数据。并且请求体超过1024B，会出现响应超慢（因为我是开启了熔断）。

三、过滤器加路线定位器

翻查源码发现ReadBodyPredicateFactory里面缓存了request body的信息，于是在自定义router中配置了ReadBodyPredicateFactory，然后在filter中通过cachedRequestBodyObject缓存字段获取request body信息。

/** * @description: 获取POST请求的请求体 * ReadBodyPredicateFactory 发现里面缓存了request body的信息， * 于是在自定义router中配置了ReadBodyPredicateFactory * @modified: */@EnableAutoConfiguration@Configurationpublic class RouteLocatorRequestBoby{ //自定义过滤器 @Resource private ReqTraceFilter reqTraceFilter; @Resource private RibbonLoadBalancerClient ribbonLoadBalancerClient; private static final String SERVICE = '/leap/**'; private static final String HTTP_PREFIX = 'http://'; private static final String COLON = ':'; @Bean public RouteLocator myRoutes(RouteLocatorBuilder builder) { //通过负载均衡获取服务实例 ServiceInstance instance = ribbonLoadBalancerClient.choose('PLATFORM-SERVICE'); //拼接路径 StringBuilder forwardAddress = new StringBuilder(HTTP_PREFIX); forwardAddress.append(instance.getHost()) .append(COLON) .append(instance.getPort()); return builder.routes() //拦截请求类型为POST Content-Type application/json application/json;charset=UTF-8 .route(r -> r.header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE + MediaType.APPLICATION_JSON_UTF8_VALUE).and().method(HttpMethod.POST).and()//获取缓存中的请求体.readBody(Object.class, readBody -> { return true;}).and().path(SERVICE)//把请求体传递给拦截器reqTraceFilter.filters(f -> { f.filter(reqTraceFilter); return f;}).uri(forwardAddress.toString())).build(); } /** * @description: 过滤器，用于获取请求体，和处理请求体业务，列如记录日志 * @modified: */@Componentpublic class ReqTraceFilter implements GlobalFilter, GatewayFilter,Ordered { private static final String CONTENT_TYPE = 'Content-Type'; private static final String CONTENT_TYPE_JSON = 'application/json'; //获取请求路由详细信息Route route = exchange.getAttribute(GATEWAY_ROUTE_BEAN) private static final String GATEWAY_ROUTE_BEAN = 'org.springframework.cloud.gateway.support.ServerWebExchangeUtils.gatewayRoute'; private static final String CACHE_REQUEST_BODY_OBJECT_KEY = 'cachedRequestBodyObject'; @Override public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) { ServerHttpRequest request = exchange.getRequest(); //判断过滤器是否执行 String requestUrl = RequestUtils.getCurrentRequest(request); if (!RequestUtils.isFilter(requestUrl)) { String bodyStr = ''; String contentType = request.getHeaders().getFirst(CONTENT_TYPE); String method = request.getMethodValue(); //判断是否为POST请求 if (null != contentType && HttpMethod.POST.name().equalsIgnoreCase(method) && contentType.contains(CONTENT_TYPE_JSON)) { Object cachedBody = exchange.getAttribute(CACHE_REQUEST_BODY_OBJECT_KEY); if(null != cachedBody){ bodyStr = cachedBody.toString(); } } if (HttpMethod.GET.name().equalsIgnoreCase(method)) { bodyStr = request.getQueryParams().toString(); } log.info('请求体内容：{}',bodyStr); } return chain.filter(exchange); } @Override public int getOrder() { return 5; }}

该方案优点：这种解决，一不会带来重复读取问题，二不会带来requestbody取不全问题。三在低版本的Spring Cloud Finchley.SR2也可以运行。

缺点：不支持multipart/form-data（异常415），这个致命。

四、通过org.springframework.cloud.gateway.filter.factory.rewrite包下有个ModifyRequestBodyGatewayFilterFactory，顾名思义，这就是修改 Request Body 的过滤器工厂类。

@Component@Slf4jpublic class ReqTraceFilter implements GlobalFilter, GatewayFilter, Ordered { @Resource private IPlatformFeignClient platformFeignClient; /** * httpheader，traceId的key名称 */ private static final String REQUESTID = 'traceId'; private static final String CONTENT_TYPE = 'Content-Type'; private static final String CONTENT_TYPE_JSON = 'application/json'; private static final String GATEWAY_ROUTE_BEAN = 'org.springframework.cloud.gateway.support.ServerWebExchangeUtils.gatewayRoute'; @Override public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) { ServerHttpRequest request = exchange.getRequest(); //判断过滤器是否执行 String requestUrl = RequestUtils.getCurrentRequest(request); if (!RequestUtils.isFilter(requestUrl)) { String bodyStr = ''; String contentType = request.getHeaders().getFirst(CONTENT_TYPE); String method = request.getMethodValue(); //判断是否为POST请求 if (null != contentType && HttpMethod.POST.name().equalsIgnoreCase(method) && contentType.contains(CONTENT_TYPE_JSON)) { ServerRequest serverRequest = new DefaultServerRequest(exchange); List<String> list = new ArrayList<>(); // 读取请求体 Mono<String> modifiedBody = serverRequest.bodyToMono(String.class) .flatMap(body -> { //记录请求体日志 final String nId = saveRequestOperLog(exchange, body); //记录日志id list.add(nId); return Mono.just(body); }); BodyInserter bodyInserter = BodyInserters.fromPublisher(modifiedBody, String.class); HttpHeaders headers = new HttpHeaders(); headers.putAll(exchange.getRequest().getHeaders()); headers.remove(HttpHeaders.CONTENT_LENGTH); CachedBodyOutputMessage outputMessage = new CachedBodyOutputMessage(exchange, headers); return bodyInserter.insert(outputMessage, new BodyInserterContext()) .then(Mono.defer(() -> { ServerHttpRequestDecorator decorator = new ServerHttpRequestDecorator( exchange.getRequest()) {@Overridepublic HttpHeaders getHeaders() { long contentLength = headers.getContentLength(); HttpHeaders httpHeaders = new HttpHeaders(); httpHeaders.putAll(super.getHeaders()); httpHeaders.put(REQUESTID,list); if (contentLength > 0) { httpHeaders.setContentLength(contentLength); } else { httpHeaders.set(HttpHeaders.TRANSFER_ENCODING, 'chunked'); } return httpHeaders;} @Overridepublic Flux<DataBuffer> getBody() { return outputMessage.getBody();} };return chain.filter(exchange.mutate().request(decorator).build()); })); } if (HttpMethod.GET.name().equalsIgnoreCase(method)) { bodyStr = request.getQueryParams().toString(); String nId = saveRequestOperLog(exchange, bodyStr); ServerHttpRequest userInfo = exchange.getRequest().mutate() .header(REQUESTID, nId).build(); return chain.filter(exchange.mutate().request(userInfo).build()); } } return chain.filter(exchange); } /** * 保存请求日志 * * @param exchange * @param requestParameters * @return */ private String saveRequestOperLog(ServerWebExchange exchange, String requestParameters) { log.debug('接口请求参数：{}', requestParameters); ServerHttpRequest request = exchange.getRequest(); String ip = Objects.requireNonNull(request.getRemoteAddress()).getAddress().getHostAddress(); SaveOperLogVO vo = new SaveOperLogVO(); vo.setIp(ip); vo.setReqUrl(RequestUtils.getCurrentRequest(request)); vo.setReqMethod(request.getMethodValue()); vo.setRequestParameters(requestParameters); Route route = exchange.getAttribute(GATEWAY_ROUTE_BEAN); //是否配置路由 if (route != null) { vo.setSubsystem(route.getId()); } ResEntity<String> res = platformFeignClient.saveOperLog(vo); log.debug('当前请求ID返回的数据：{}', res); return res.getData(); } @Override public int getOrder() { return 5; }}

该方案：完美解决以上所有问题

参考文档：https://www.codercto.com/a/52970.html

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