Spring Cloud（十八）：Spring Cloud Gateway（读取、修改 Request Body）

public class ValidateFilter implements GlobalFilter, Ordered {
    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        ServerHttpRequest request = exchange.getRequest();
        HttpHeaders headers = request.getHeaders();
        MultiValueMap<String, HttpCookie> cookies = request.getCookies();
        MultiValueMap<String, String> queryParams = request.getQueryParams();
        Flux<DataBuffer> body = request.getBody();
        return null;
    }

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

.route("rewrite_request_upper", r -> r.host("*.rewriterequestupper.org")
	.filters(f -> f.prefixPath("/httpbin")
			.addResponseHeader("X-TestHeader", "rewrite_request_upper")
			.modifyRequestBody(String.class, String.class,
					(exchange, s) -> {
						return Mono.just(s.toUpperCase()+s.toUpperCase());
					})
	).uri(uri)
)

/**
 * @author yibo
 */
public class ValidateFilter implements GlobalFilter, Ordered {


    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        ServerRequest serverRequest = new DefaultServerRequest(exchange);
        // mediaType
        MediaType mediaType = exchange.getRequest().getHeaders().getContentType();
        // read & modify body
        Mono<String> modifiedBody = serverRequest.bodyToMono(String.class)
                .flatMap(body -> {
                    if (MediaType.APPLICATION_FORM_URLENCODED.isCompatibleWith(mediaType)) {

                        // origin body map
                        Map<String, Object> bodyMap = decodeBody(body);

                        // TODO decrypt & auth

                        // new body map
                        Map<String, Object> newBodyMap = new HashMap<>();

                        return Mono.just(encodeBody(newBodyMap));
                    }
                    return Mono.empty();
                });

        BodyInserter bodyInserter = BodyInserters.fromPublisher(modifiedBody, String.class);
        HttpHeaders headers = new HttpHeaders();
        headers.putAll(exchange.getRequest().getHeaders());

        // the new content type will be computed by bodyInserter
        // and then set in the request decorator
        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()) {
                        @Override
                        public HttpHeaders getHeaders() {
                            long contentLength = headers.getContentLength();
                            HttpHeaders httpHeaders = new HttpHeaders();
                            httpHeaders.putAll(super.getHeaders());
                            if (contentLength > 0) {
                                httpHeaders.setContentLength(contentLength);
                            } else {
                                httpHeaders.set(HttpHeaders.TRANSFER_ENCODING, "chunked");
                            }
                            return httpHeaders;
                        }

                        @Override
                        public Flux<DataBuffer> getBody() {
                            return outputMessage.getBody();
                        }
                    };
                    return chain.filter(exchange.mutate().request(decorator).build());
                }));
    }

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

    private Map<String, Object> decodeBody(String body) {
        return Arrays.stream(body.split("&"))
                .map(s -> s.split("="))
                .collect(Collectors.toMap(arr -> arr[0], arr -> arr[1]));
    }

    private String encodeBody(Map<String, Object> map) {
        return map.entrySet().stream().map(e -> e.getKey() + "=" + e.getValue()).collect(Collectors.joining("&"));
    }
}