SpringCloudGateway集成SpringDoc CORS问题

集成SpringDoc后，在gateway在线文档界面，请求具体的服务接口，报CORS问题

Failed to fetch.
Possible Reasons:
CORS
Network Failure
URL scheme must be “http” or “https” for CORS request.

分析

其实是网关直接请求具体服务/v3/api-docs接口(默认)，获取文档数据，里面包含该服务注册上来的地址，gateway swagger-ui解析该接口数据，根据里面的地址直接请求。可是网关地址，跟具体的服务地址肯定不同源，在gateway集成界面请求，肯定报跨的问题。
或者是该微服务群，只能通过网关访问，直接请求具体的服务地址，网络不通。

{"openapi": "3.0.1","info": {"title": "XX服务","description": "XX服务开发接口文档","version": "1.0.0"},"servers": [{"url": "http://[2408:8456:601:9f52:225d:8f68:5e14:6ff4]:8201","description": "Generated server url"}]
}

思路

通过在gateway编写全局GatewayFilter，拦截集成时请求的 /xx/v3/api-docs接口(默认)接口，修改返回的数据，在servers写入通过网关直接访问的地址，就能解决在线文档请求接口，存在的跨域问题和网络不通问题。

实现

/*** 处理服务 /v3/api-docs接口返回的数据，在servers里添加可以通过网关直接访问的地址*/
@Slf4j
@Component
@ConditionalOnProperty(name = SPRINGDOC_ENABLED, matchIfMissing = true)
public class DocServiceUrlModifyGatewayFilter implements GlobalFilter, Ordered {@Autowiredprivate SpringDocConfigProperties springDocConfigProperties;@Overridepublic Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {//直接用配置类的值，默认值是 /v3/api-docsString apiPath = springDocConfigProperties.getApiDocs().getPath();ServerHttpRequest request = exchange.getRequest();ServerHttpResponse response = exchange.getResponse();URI uri = request.getURI();//非正常状态跳过if (response.getStatusCode().value() != HttpStatus.OK.value()) {return chain.filter(exchange);}//非springdoc文档不拦截if (!(StringUtils.isNotBlank(uri.getPath()) && uri.getPath().endsWith(apiPath))) {return chain.filter(exchange);}String uriString = uri.toString();String gatewayUrl = uriString.substring(0, uriString.lastIndexOf(apiPath));DataBufferFactory bufferFactory = response.bufferFactory();ServerHttpResponseDecorator decoratedResponse = new ServerHttpResponseDecorator(response) {@Overridepublic Mono<Void> writeWith(Publisher<? extends DataBuffer> body) {//不处理if (!(body instanceof Flux)) {return super.writeWith(body);}//处理SpringDoc-OpenAPIFlux<? extends DataBuffer> fluxBody = (Flux<? extends DataBuffer>) body;return super.writeWith(fluxBody.buffer().map(dataBuffers -> {DataBufferFactory dataBufferFactory = new DefaultDataBufferFactory();DataBuffer join = dataBufferFactory.join(dataBuffers);byte[] content = new byte[join.readableByteCount()];join.read(content);DataBufferUtils.release(join);try {// 流转为字符串String responseData = new String(content, StandardCharsets.UTF_8);Map<String, Object> map = JsonUtils.json2Object(responseData, Map.class);//处理返回的数据Object serversObject = map.get("servers");if (null != serversObject) {List<Map<String, Object>> servers = (List<Map<String, Object>>) serversObject;Map<String, Object> gatewayServer = new HashMap<>();//网关地址gatewayServer.put("url", gatewayUrl);gatewayServer.put("description", "Gateway server url");//添加到第1个servers.add(0, gatewayServer);map.put("servers", servers);responseData = JsonUtils.object2Json(map);byte[] uppedContent = responseData.getBytes(StandardCharsets.UTF_8);response.getHeaders().setContentLength(uppedContent.length);return bufferFactory.wrap(uppedContent);}} catch (Exception e) {log.error(e.getMessage(), e);}return bufferFactory.wrap(content);}));}};// replace response with decoratorreturn chain.filter(exchange.mutate().response(decoratedResponse).build());}@Overridepublic int getOrder() {return -2;}class JsonUtils {public static final ObjectMapper OBJECT_MAPPER = createObjectMapper();/*** 初始化ObjectMapper** @return*/private static ObjectMapper createObjectMapper() {ObjectMapper objectMapper = new ObjectMapper();objectMapper.configure(JsonParser.Feature.ALLOW_UNQUOTED_FIELD_NAMES, true);objectMapper.configure(DeserializationFeature.ACCEPT_EMPTY_STRING_AS_NULL_OBJECT, true);objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
//        objectMapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);objectMapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, true);//        objectMapper.registerModule(new Hibernate4Module().enable(Hibernate4Module.Feature.FORCE_LAZY_LOADING));objectMapper.registerModule(new JavaTimeModule());return objectMapper;}public static String object2Json(Object o) {StringWriter sw = new StringWriter();JsonGenerator gen = null;try {gen = new JsonFactory().createGenerator(sw);OBJECT_MAPPER.writeValue(gen, o);} catch (IOException e) {throw new RuntimeException("不能序列化对象为Json", e);} finally {if (null != gen) {try {gen.close();} catch (IOException e) {throw new RuntimeException("不能序列化对象为Json", e);}}}return sw.toString();}/*** 将 json 字段串转换为 对象.** @param json  字符串* @param clazz 需要转换为的类* @return*/public static <T> T json2Object(String json, Class<T> clazz) {try {return OBJECT_MAPPER.readValue(json, clazz);} catch (IOException e) {throw new RuntimeException("将 Json 转换为对象时异常,数据是:" + json, e);}}}
}