spring cloud gateway 获取入参

本文介绍如何在Spring Cloud Gateway中实现POST请求体的缓存与读取,通过自定义过滤器解决请求体只能被消费一次的问题,确保日志记录和业务处理都能正确获取请求数据。

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在获取入参的时候,get方式的接口可以直接获取到,但是post形式的body获取以后会造成无法再使用,所以必须经过一层转换以后再读取。

直接上代码


@Component
public class CacheBodyGatewayFilter implements GlobalFilter, Ordered {
    public static final String CACHE_REQUEST_BODY_OBJECT_KEY = "cachedRequestBodyObject";

    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        if (exchange.getRequest().getHeaders().getContentType() == null) {
            return chain.filter(exchange);
        } else {
            return DataBufferUtils.join(exchange.getRequest().getBody())
                    .flatMap(dataBuffer -> {
                        DataBufferUtils.retain(dataBuffer);
                        Flux<DataBuffer> cachedFlux = Flux
                                .defer(() -> Flux.just(dataBuffer.slice(0, dataBuffer.readableByteCount())));
                        ServerHttpRequest mutatedRequest = new ServerHttpRequestDecorator(
                                exchange.getRequest()) {
                            @Override
                            public Flux<DataBuffer> getBody() {
                                return cachedFlux;
                            }

                        };
                        exchange.getAttributes().put(CACHE_REQUEST_BODY_OBJECT_KEY, cachedFlux);

                        return chain.filter(exchange.mutate().request(mutatedRequest).build());
                    });
        }
    }

    @Override
    public int getOrder() {
    	//这个代表了执行顺序,值越小越先执行 
        return Ordered.HIGHEST_PRECEDENCE;
    }
}

接下来是读取方法


@Component
public class AccessLogGlobalFilter implements GlobalFilter, Ordered {
    public static final String CACHE_REQUEST_BODY_OBJECT_KEY = "cachedRequestBodyObject";


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

        //Record only http requests (including https)
        String schema = request.getURI().getScheme();
        if ((!"http".equals(schema) && !"https".equals(schema))) {
            return chain.filter(exchange);
        }
		//我自定义的实体类,如果不需要 你可以直接删掉
        LogDTO logDTO = new LogDTO();
        logDTO.setPath(request.getURI().getPath());
        logDTO.setQueryParams(request.getQueryParams());
        logDTO.setMethod(request.getMethod().name());
        logDTO.setIp(request.getRemoteAddress().getHostName());
        logDTO.setUserAgent(request.getHeaders().getFirst("User-Agent"));
        exchange.getAttributes().put("startTime", System.currentTimeMillis());


        //获取request body
        Flux<DataBuffer> cachedBody = exchange.getAttribute(CACHE_REQUEST_BODY_OBJECT_KEY);
        if(cachedBody!=null){
            String raw = toRaw(cachedBody);
            logDTO.setParams(raw);
        }


        return returnMono(chain, exchange, logDTO);
    }

    private Mono<Void> returnMono(GatewayFilterChain chain, ServerWebExchange exchange, LogDTO logDTO) {
        return chain.filter(exchange).then(Mono.fromRunnable(() -> {
            Long startTime = exchange.getAttribute("startTime");
            if (startTime != null) {
                long executeTime = (System.currentTimeMillis() - startTime);
                logDTO.setTime(executeTime);
                logDTO.setResultCode(Objects.requireNonNull(exchange.getResponse().getStatusCode()).value());
                StaticLog.info("=================================");
                StaticLog.info("请求方式:[{}]", logDTO.getMethod());
                StaticLog.info("路径:[{}]", logDTO.getPath());
                StaticLog.info("IP:[{}]", logDTO.getIp());
                StaticLog.info("UserAgent:[{}]", logDTO.getUserAgent());
                StaticLog.info("请求格式[{}]", exchange.getResponse().getHeaders().getContentType());
                StaticLog.info("时长:[{}]", executeTime);
                StaticLog.info("code:[{}]", logDTO.getResultCode());
                StaticLog.info("body:[{}]", logDTO.getParams());
            }
        }));
    }

    @Override
    public int getOrder() {
    	//这个filter的执行顺序要在 CacheBodyGatewayFilter 类之后 否则找不到缓存的值
        return Ordered.HIGHEST_PRECEDENCE+1;
    }

    /**
     * 用于获取请求参数
     *
     * @param body
     * @return
     */
    private static String toRaw(Flux<DataBuffer> body) {
        AtomicReference<String> rawRef = new AtomicReference<>();
        body.subscribe(buffer -> {
            byte[] bytes = new byte[buffer.readableByteCount()];
            buffer.read(bytes);
            DataBufferUtils.release(buffer);
            rawRef.set(Strings.fromUTF8ByteArray(bytes));
        });
        return rawRef.get();
    }

}

### 如何在 Spring Cloud Gateway获取 HTTP 请求对象及数 #### 使用 `ServerWebExchange` 获取请求信息 在 Spring Cloud Gateway 的环境中,所有的请求处理都是基于 `ServerWebExchange` 对象完成的。此对象提供了访问当前HTTP请求和响应的能力[^1]。 ```java @Component public class CustomGlobalFilter implements GlobalFilter { @Override public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) { ServerHttpRequest request = exchange.getRequest(); // 打印请求路径 System.out.println("Request Path: " + request.getURI().getPath()); // 处理逻辑... return chain.filter(exchange); } } ``` #### 解决 POST 请求体只能读取一次的问题 由于 Reactor Netty 和 WebFlux 的特性,在 Spring Cloud Gateway 中直接读取请求体会消耗掉输流,使得后续处理器无法再读取该数据。为了克服这个问题,可以采用缓存请求体的方式: - 将原始请求转换成新的带有相同属性但可重复读取的内容的新请求; - 利用自定义过滤器来实现上述功能[^2]。 ```java import org.springframework.core.io.buffer.DataBuffer; import reactor.core.publisher.Flux; // 缓存请求体并创建新请求的方法 private static ServerHttpRequest copyRequestBody(ServerHttpRequest request) throws IOException { Flux<DataBuffer> cachedBody = request.getBody() .cache(); ServerHttpRequestDecorator decoratedRequest = new ServerHttpRequestDecorator(request) { @Override public Flux<DataBuffer> getBody() { return cachedBody; } }; return decoratedRequest; } ``` #### 日志记录中的应用实例 当希望在网关层面对所有进系统的 API 调用做统一的日志管理时,可以通过全局过滤器截获每一个到来的请求,并从中提取必要的元数据以及可能存在的 JSON 形式的负载内容进行记录。 ```java @Slf4j @Component public class LoggingFilter extends AbstractGatewayFilterFactory<LoggingFilter.Config> { private final ObjectMapper objectMapper = new ObjectMapper(); public LoggingFilter() { super(Config.class); } @Override public GatewayFilter apply(Config config) { return (exchange, chain) -> { try { String bodyString = extractBodyAsString(exchange); log.info("Received Request:\nMethod:{}\nPath:{}\nHeaders:{}\nBody:{}", exchange.getRequest().getMethod(), exchange.getRequest().getURI().getPath(), exchange.getRequest().getHeaders(), bodyString); return chain.filter(exchange.mutate().request(copyRequestBody(exchange.getRequest())).build()); } catch (Exception e) { throw new RuntimeException(e.getMessage(), e); } }; } private String extractBodyAsString(ServerWebExchange exchange) throws Exception { StringBuilder builder = new StringBuilder(); exchange.getAttributeOrDefault("cached_request_body", "") .toString() .chars() .forEach(c -> builder.append((char)c)); if(builder.length() == 0){ return ""; } return builder.toString(); } public static class Config {} } ```
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