这几天有个对SpringCloud-Gateway网关请求参数做安全校验的需求，网上多数教程不适用于SpringBoot2.1+版本。我在SpringCloud gateway Github中的Issues找到了答案，放上连接：作者采纳的答案。

具体代码如下：

@Component
public class CacheBodyGatewayFilter implements Ordered, GlobalFilter {

    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() {
        return Ordered.HIGHEST_PRECEDENCE;
    }
}

@Component
@Slf4j
public class DecodeGatewayFilter 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();

        //获取request body
        Flux<DataBuffer> cachedBody = exchange.getAttribute(CACHE_REQUEST_BODY_OBJECT_KEY);
        if(cachedBody!=null){
             String raw = toRaw(cachedBody);
            JSONObject jsonObject = JSON.parseObject(raw);
            log.info("request body is:{}", jsonObject);
        //Todo 获取到RequestBody 做你想做的操作
        }
        ServerHttpRequest.Builder builder = request.mutate();
        return chain.filter(exchange.mutate().request(builder.build()).build());
    }

    @Override
    public int getOrder() {
        return -99;
    }

    /**
     * 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();
    }
}

怎么用——》添加这两个过滤器到你的Gateway中