Spring-Cloud-Gateway之请求响应日志打印过滤器

Gateway网关开发中我们的大部分时间都是在开发各种各样功能的过滤器，下面为网关，请求，响应日志打印的过滤器，以及涉及到的类

• DefaultLogFilter

public class DefaultLogFilter implements GlobalFilter, Ordered {
    /**
     * 日志信息
     */
    private static final Logger logger = LoggerFactory.getLogger(DefaultLogFilter.class);

    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        long startTime = System.currentTimeMillis();
        String trace = exchange.getRequest().getHeaders().getFirst("trace");
        ServerRequest serverRequest = new DefaultServerRequest(exchange);
        return serverRequest.bodyToMono(String.class).flatMap(reqBody -> {
            //重写原始请求
            ServerHttpRequestDecorator decorator = new ServerHttpRequestDecorator(exchange.getRequest()) {
                @Override
                public HttpHeaders getHeaders() {
                    HttpHeaders httpHeaders = new HttpHeaders();
                    httpHeaders.putAll(super.getHeaders());
                    return httpHeaders;
                }

                @Override
                public Flux<DataBuffer> getBody() {
                    //打印原始请求日志
                    logger.info("[Trace:{}]-gateway request:headers=[{}],body=[{}]", trace, getHeaders(), reqBody);
                    return Flux.just(reqBody).map(bx -> exchange.getResponse().bufferFactory().wrap(bx.getBytes()));
                }
            };
            //重写原始响应
            BodyHandlerServerHttpResponseDecorator responseDecorator = new BodyHandlerServerHttpResponseDecorator(
                    initBodyHandler(exchange, startTime), exchange.getResponse());

            return chain.filter(exchange.mutate().request(decorator).response(responseDecorator).build());
        });
    }

    @Override
    public int getOrder() {
        //在NettyWriteResponseFilter之前
        return NettyWriteResponseFilter.WRITE_RESPONSE_FILTER_ORDER - 20;
    }

    /**
     * 响应body处理，添加响应的打印
     *
     * @param exchange
     * @param startTime
     * @return
     */
    protected BodyHandlerFunction initBodyHandler(ServerWebExchange exchange, long startTime) {
        return (resp, body) -> {
            //拦截
            String trace = exchange.getRequest().getHeaders().getFirst("trace");
            MediaType originalResponseContentType = exchange.getAttribute(ORIGINAL_RESPONSE_CONTENT_TYPE_ATTR);
            HttpHeaders httpHeaders = new HttpHeaders();
            httpHeaders.setContentType(originalResponseContentType);
            DefaultClientResponseAdapter clientResponseAdapter = new DefaultClientResponseAdapter(body, httpHeaders);
            Mono<String> bodyMono = clientResponseAdapter.bodyToMono(String.class);
            return bodyMono.flatMap((respBody) -> {
                //打印返回响应日志
                logger.info("[Trace:{}]-gateway response:ct=[{}], status=[{}],headers=[{}],body=[{}]", trace,
                        System.currentTimeMillis() - startTime, resp.getStatusCode(), resp.getHeaders(), respBody);
                return resp.writeWith(Flux.just(respBody).map(bx -> resp.bufferFactory().wrap(bx.getBytes())));
            }).then();
        };
    }
}

• BodyHandlerFunction

/**
 * 响应body拦截处理接口
 */
public interface BodyHandlerFunction
        extends BiFunction<ServerHttpResponse, Publisher<? extends DataBuffer>, Mono<Void>> {
}

• BodyHandlerServerHttpResponseDecorator

/**
 * ServerHttpResponse包装类，通过ResponseBodyHandlerFunction处理响应body
 */
public class BodyHandlerServerHttpResponseDecorator extends ServerHttpResponseDecorator {

    /**
     * body 处理拦截器
     */
    private BodyHandlerFunction bodyHandler = initDefaultBodyHandler();

    /**
     * 构造函数
     *
     * @param bodyHandler
     * @param delegate
     */
    public BodyHandlerServerHttpResponseDecorator(BodyHandlerFunction bodyHandler, ServerHttpResponse delegate) {
        super(delegate);
        if (bodyHandler != null) {
            this.bodyHandler = bodyHandler;
        }
    }

    @Override
    public Mono<Void> writeWith(Publisher<? extends DataBuffer> body) {
        //body 拦截处理器处理响应
        return bodyHandler.apply(getDelegate(), body);
    }

    @Override
    public Mono<Void> writeAndFlushWith(Publisher<? extends Publisher<? extends DataBuffer>> body) {
        return writeWith(Flux.from(body).flatMapSequential(p -> p));
    }

    /**
     * 默认body拦截处理器
     *
     * @return
     */
    private BodyHandlerFunction initDefaultBodyHandler() {
        return (resp, body) -> resp.writeWith(body);
    }
}

• DefaultClientResponseAdapter

/**
 * ClientResponse适配器，用于将body转换为DefaultClientResponse对象进而对body流反序列化
 *
 */
public class DefaultClientResponseAdapter extends DefaultClientResponse {

    /**
     * @param body
     * @param httpHeaders
     */
    public DefaultClientResponseAdapter(Publisher<? extends DataBuffer> body,
            HttpHeaders httpHeaders) {
        this(new ResponseAdapter(body, httpHeaders),
                ExchangeStrategies.withDefaults());
    }

    /**
     * @param response
     * @param strategies
     */
    public DefaultClientResponseAdapter(ClientHttpResponse response,
            ExchangeStrategies strategies) {
        super(response, strategies);
    }

    /**
     * ClientHttpResponse 适配器
     */
    static class ResponseAdapter implements ClientHttpResponse {
        /**
         * 响应数据
         */
        private final Flux<DataBuffer> flux;
        /**
         *
         */
        private final HttpHeaders headers;

        public ResponseAdapter(Publisher<? extends DataBuffer> body,
                HttpHeaders headers) {
            this.headers = headers;
            if (body instanceof Flux) {
                flux = (Flux) body;
            } else {
                flux = ((Mono) body).flux();
            }
        }

        @Override
        public Flux<DataBuffer> getBody() {
            return flux;
        }

        @Override
        public HttpHeaders getHeaders() {
            return headers;
        }

        @Override
        public HttpStatus getStatusCode() {
            return null;
        }

        @Override
        public int getRawStatusCode() {
            return 0;
        }

        @Override
        public MultiValueMap<String, ResponseCookie> getCookies() {
            return null;
        }
    }
}