spring-cloud-gateway获取post请求body参数以及响应数据

@Component
@Slf4j
@AllArgsConstructor
public class HttpPostBodyFilter implements GlobalFilter, Ordered {

    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        ServerHttpRequest request = exchange.getRequest();

        String method = request.getMethodValue();
        String contentType = request.getHeaders().getFirst("Content-Type");
        if ("POST".equals(method) && contentType.startsWith("multipart/form-data")){
            return DataBufferUtils.join(exchange.getRequest().getBody())
                    .flatMap(dataBuffer -> {
                        byte[] bytes = new byte[dataBuffer.readableByteCount()];
                        dataBuffer.read(bytes);
                        try {
                            String bodyString = new String(bytes, "utf-8");
                            log.info(bodyString);
                            exchange.getAttributes().put("POST_BODY",bodyString);
                        } catch (UnsupportedEncodingException e) {
                            e.printStackTrace();
                        }
                        DataBufferUtils.release(dataBuffer);
                        Flux<DataBuffer> cachedFlux = Flux.defer(() -> {
                            DataBuffer buffer = exchange.getResponse().bufferFactory()
                                    .wrap(bytes);
                            return Mono.just(buffer);
                        });

                        ServerHttpRequest mutatedRequest = new ServerHttpRequestDecorator(
                                exchange.getRequest()) {
                            @Override
                            public Flux<DataBuffer> getBody() {
                                return cachedFlux;
                            }
                        };
                        return chain.filter(exchange.mutate().request(mutatedRequest)
                                        .build());
                    });
        }
        return chain.filter(exchange);
    }

    @Override
    public int getOrder() {
        return -200;
    }
}

主要思路就是在优先级最高的过滤器里面，CacheBodyGlobalFilter这个全局过滤器的目的就是把原有的request请求中的body内容读出来，并且使用ServerHttpRequestDecorator这个请求装饰器对request进行包装，重写getBody方法，并把包装后的请求放到过滤器链中传递下去。这样后面的过滤器中再使用exchange.getRequest().getBody()来获取body时，实际上就是调用的重载后的getBody方法，获取的最先已经缓存了的body数据。这样就能够实现body的多次读取了。

过滤器优先级不一定是最高，但是要在要获取body之前执行，然后后面在身份鉴定的等过滤器里面，获取到body

@Component
@Slf4j
public class WrapperResponseGlobalFilter implements GlobalFilter, Ordered {
    @Override
    public int getOrder() {
        return -2;
    }
 
    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        ServerHttpRequest serverHttpRequest = exchange.getRequest();
        ServerHttpResponse originalResponse = exchange.getResponse();
        //如果是post请求，将请求体取出来，再写入
        HttpMethod method = serverHttpRequest.getMethod();
        //请求参数，post从请求里获取请求体
        String requestBodyStr = HttpMethod.POST.equals(method) ? resolveBodyFromRequest(serverHttpRequest) : null;
        DataBufferFactory bufferFactory = originalResponse.bufferFactory();
        ServerHttpResponseDecorator decoratedResponse = new ServerHttpResponseDecorator(originalResponse) {
            @Override
            public Mono<Void> writeWith(Publisher<? extends DataBuffer> body) {
                if (body instanceof Flux) {
                    Flux<? extends DataBuffer> fluxBody = (Flux<? extends DataBuffer>) body;
                    return super.writeWith(fluxBody.buffer().map(dataBuffers -> {//解决返回体分段传输
                        StringBuffer stringBuffer = new StringBuffer();
                        dataBuffers.forEach(dataBuffer -> {
                            byte[] content = new byte[dataBuffer.readableByteCount()];
                            dataBuffer.read(content);
                            DataBufferUtils.release(dataBuffer);
                            try {
                                stringBuffer.append(new String(content, "utf-8"));
                            } catch (Exception e) {
                                log.error("--list.add--error", e);
                            }
                        });
                        String result = stringBuffer.toString();
                        //TODO，result就是response的值，想修改、查看就随意而为了
                        String url = serverHttpRequest.getPath().toString();
                        String urlParams = UrlUtil.getParamsByMap(serverHttpRequest.getQueryParams().toSingleValueMap());
 
                        JSONObject jsonObject = JSONObject.parseObject(result);
                        log.info("请求长度：" + StringUtils.length(requestBodyStr) + "，返回data长度:" + StringUtils.length(jsonObject.getString("data")));
                        log.info("请求地址:【{}】请求参数:GET【{}】|POST:【
{}
】,响应数据:【
{}
】", url, urlParams, requestBodyStr, result);
 
                        byte[] uppedContent = new String(result.getBytes(), Charset.forName("UTF-8")).getBytes();
                        originalResponse.getHeaders().setContentLength(uppedContent.length);
                        return bufferFactory.wrap(uppedContent);
                    }));
                }
                // if body is not a flux. never got there.
                return super.writeWith(body);
            }
        };
        // replace response with decorator
        return chain.filter(exchange.mutate().response(decoratedResponse).build());
    }
 
    /**
     * 从Flux<DataBuffer>中获取字符串的方法
     *
     * @return 请求体
     */
    private String resolveBodyFromRequest(ServerHttpRequest serverHttpRequest) {
        //获取请求体
        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());
        });
        //获取request body
        return bodyRef.get();
    }
}

这里可以把请求地址、参数、body、响应数据一起打印出来，测试的post请求

请求参数有56.97kb，后端order-center的接收打印，把整个数据完全接收并返回出去

网关的打印请求参数数据

再来一个get请求的

其他的put、delete等请求均试过正常请求

用postman的压测结果和对比，数据都完全正常，并且能通过json格式化，说明数据格式也保持了一致

代码还有很多可以优化改进的地方，根据自己的也无需求来，比如签名、token等统一校验处理