背景介绍

项目使用的技术栈是Spring Cloud，有个功能需求是：

业务上，在Spring Cloud Gateway模块的服务已经可以获取到token,并且已实现鉴权通过后从token获取到身份信息；

现在希望把身份信息，填充到request参数里面（这里把多个数据封装成一个BaseDTO对象，用于扩展）。

后续处理具体业务的微服务模块，在controller层的方法传参，只要继承了BaseDTO对象，就可以直接获取到身份信息，用于业务逻辑处理。

问题描述

简单来说，问题就是 Spring Cloud Gateway 如何动态添加请求参数。

Spring Cloud Gateway Add Request Parameter

1. 查看官方文档，提供了下面的示例：

docs.spring.io/spring-clou…

但是是在配置文件写明的，看起来好像只能是固定值。

2. 在github上看到也有人提了类似问题，

github.com/spring-clou…

但是实现的效果也跟配置文件差不多。

3. 在stackoverflow上也查了类似回答：

stackoverflow.com/questions/6…

大概思路有了方向。

解决方案

在 Spring Cloud Gateway 源码上，发现了这两个类 AddRequestParameterGatewayFilterFactory 和 ModifyRequestBodyGatewayFilterFactory

代码内容如下：

AddRequestParameterGatewayFilterFactory

//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by FernFlower decompiler)
//package org.springframework.cloud.gateway.filter.factory;import java.net.URI;
import org.springframework.cloud.gateway.filter.GatewayFilter;
import org.springframework.cloud.gateway.filter.factory.AbstractNameValueGatewayFilterFactory.NameValueConfig;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.util.StringUtils;
import org.springframework.web.util.UriComponentsBuilder;public class AddRequestParameterGatewayFilterFactory extends AbstractNameValueGatewayFilterFactory {public AddRequestParameterGatewayFilterFactory() {}public GatewayFilter apply(NameValueConfig config) {return (exchange, chain) -> {URI uri = exchange.getRequest().getURI();StringBuilder query = new StringBuilder();String originalQuery = uri.getRawQuery();if (StringUtils.hasText(originalQuery)) {query.append(originalQuery);if (originalQuery.charAt(originalQuery.length() - 1) != '&') {query.append('&');}}query.append(config.getName());query.append('=');query.append(config.getValue());try {URI newUri = UriComponentsBuilder.fromUri(uri).replaceQuery(query.toString()).build(true).toUri();ServerHttpRequest request = exchange.getRequest().mutate().uri(newUri).build();return chain.filter(exchange.mutate().request(request).build());} catch (RuntimeException var8) {throw new IllegalStateException("Invalid URI query: \"" + query.toString() + "\"");}};}
}复制代码

ModifyRequestBodyGatewayFilterFactory

//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by FernFlower decompiler)
//package org.springframework.cloud.gateway.filter.factory.rewrite;import java.util.Map;
import org.springframework.cloud.gateway.filter.GatewayFilter;
import org.springframework.cloud.gateway.filter.factory.AbstractGatewayFilterFactory;
import org.springframework.cloud.gateway.support.BodyInserterContext;
import org.springframework.cloud.gateway.support.CachedBodyOutputMessage;
import org.springframework.cloud.gateway.support.DefaultServerRequest;
import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.http.HttpHeaders;
import org.springframework.http.codec.ServerCodecConfigurer;
import org.springframework.http.server.reactive.ServerHttpRequestDecorator;
import org.springframework.web.reactive.function.BodyInserter;
import org.springframework.web.reactive.function.BodyInserters;
import org.springframework.web.reactive.function.server.ServerRequest;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;public class ModifyRequestBodyGatewayFilterFactory extends AbstractGatewayFilterFactory {public ModifyRequestBodyGatewayFilterFactory() {super(ModifyRequestBodyGatewayFilterFactory.Config.class);}/** @deprecated */@Deprecatedpublic ModifyRequestBodyGatewayFilterFactory(ServerCodecConfigurer codecConfigurer) {this();}public GatewayFilter apply(ModifyRequestBodyGatewayFilterFactory.Config config) {return (exchange, chain) -> {Class inClass = config.getInClass();ServerRequest serverRequest = new DefaultServerRequest(exchange);Mono modifiedBody = serverRequest.bodyToMono(inClass).flatMap((o) -> {return config.rewriteFunction.apply(exchange, o);});BodyInserter bodyInserter = BodyInserters.fromPublisher(modifiedBody, config.getOutClass());CachedBodyOutputMessage outputMessage = new CachedBodyOutputMessage(exchange, exchange.getRequest().getHeaders());return bodyInserter.insert(outputMessage, new BodyInserterContext()).then(Mono.defer(() -> {ServerHttpRequestDecorator decorator = new ServerHttpRequestDecorator(exchange.getRequest()) {public HttpHeaders getHeaders() {HttpHeaders httpHeaders = new HttpHeaders();httpHeaders.putAll(super.getHeaders());httpHeaders.set("Transfer-Encoding", "chunked");return httpHeaders;}public Flux getBody() {return outputMessage.getBody();}};return chain.filter(exchange.mutate().request(decorator).build());}));};}public static class Config {private Class inClass;private Class outClass;private Map inHints;private Map outHints;private RewriteFunction rewriteFunction;public Config() {}public Class getInClass() {return this.inClass;}public ModifyRequestBodyGatewayFilterFactory.Config setInClass(Class inClass) {this.inClass = inClass;return this;}public Class getOutClass() {return this.outClass;}public ModifyRequestBodyGatewayFilterFactory.Config setOutClass(Class outClass) {this.outClass = outClass;return this;}public Map getInHints() {return this.inHints;}public ModifyRequestBodyGatewayFilterFactory.Config setInHints(Map inHints) {this.inHints = inHints;return this;}public Map getOutHints() {return this.outHints;}public ModifyRequestBodyGatewayFilterFactory.Config setOutHints(Map outHints) {this.outHints = outHints;return this;}public RewriteFunction getRewriteFunction() {return this.rewriteFunction;}public  ModifyRequestBodyGatewayFilterFactory.Config setRewriteFunction(Class inClass, Class outClass, RewriteFunction rewriteFunction) {this.setInClass(inClass);this.setOutClass(outClass);this.setRewriteFunction(rewriteFunction);return this;}public ModifyRequestBodyGatewayFilterFactory.Config setRewriteFunction(RewriteFunction rewriteFunction) {this.rewriteFunction = rewriteFunction;return this;}}
}复制代码

实际上，可以当作官方提供的参考示例。

照着类似内容，我们可以依样画葫芦，在自己的网关过滤器上实现添加参数的功能。

实现代码

鉴权过滤器主要处理流程

@Component
public class AuthFilter implements GlobalFilter, Ordered {private static final Logger LOGGER = LoggerFactory.getLogger(AuthFilter.class);private static AntPathMatcher antPathMatcher;static {antPathMatcher = new AntPathMatcher();}@Overridepublic int getOrder() {return FilterOrderConstant.getOrder(this.getClass().getName());}@Overridepublic Mono filter(ServerWebExchange exchange, GatewayFilterChain chain) {ServerHttpRequest request = exchange.getRequest();URI uri = request.getURI();String url = uri.getPath();String host = uri.getHost();// 跳过不需要验证的路径Stream skipAuthUrls = UrlConstant.skipAuthUrls.stream();if(skipAuthUrls.anyMatch(path -> antPathMatcher.match(path, url))){// 直接返回ServerHttpRequest.Builder builder = request.mutate();return chain.filter(exchange.mutate().request(builder.build()).build());}// 从请求头中取出tokenString token = request.getHeaders().getFirst("Authorization");// 取出token包含的身份信息// 校验token逻辑不再阐述BaseDTO baseDTO = getClaim(token);if(null == baseDTO){// 鉴权不通过，拿不到身份信息return illegalResponse(exchange, "{\"code\": \"401\",\"msg\": \"unauthorized.\"}");}// 将现在的request，添加当前身份信息ServerHttpRequest.Builder builder = request.mutate();Stream addRequestParameterUrls = UrlConstant.addRequestParameterUrls.stream();if (addRequestParameterUrls.anyMatch(path -> antPathMatcher.match(path, url))){// 需要添加请求参数if(request.getMethod() == HttpMethod.GET){// get请求 处理参数return addParameterForGetMethod(exchange, chain, uri, baseDTO, builder);}if(request.getMethod() == HttpMethod.POST){// post请求 处理参数MediaType contentType = request.getHeaders().getContentType();if(MediaType.APPLICATION_JSON.equals(contentType)|| MediaType.APPLICATION_JSON_UTF8.equals(contentType)){// 请求内容为 application jsonreturn addParameterForPostMethod(exchange, chain, baseDTO);}if (MediaType.MULTIPART_FORM_DATA.isCompatibleWith(contentType)) {// 请求内容为 form datareturn addParameterForFormData(exchange, chain, baseDTO, builder);}}if(request.getMethod() == HttpMethod.PUT){// put请求 处理参数// 走 post 请求流程return addParameterForPostMethod(exchange, chain, baseDTO);}if(request.getMethod() == HttpMethod.DELETE){// delete请求 处理参数// 走 get 请求流程return addParameterForGetMethod(exchange, chain, uri, baseDTO, builder);}}// 当前过滤器filter执行结束return chain.filter(exchange.mutate().request(builder.build()).build());}}
复制代码

Get请求 添加参数

/*** get请求，添加参数* @param exchange* @param chain* @param uri* @param baseDTO* @param builder* @return*/private Mono addParameterForGetMethod(ServerWebExchange exchange, GatewayFilterChain chain, URI uri, BaseDTO baseDTO, ServerHttpRequest.Builder builder) {StringBuilder query = new StringBuilder();String originalQuery = uri.getQuery();if (StringUtils.hasText(originalQuery)) {query.append(originalQuery);if (originalQuery.charAt(originalQuery.length() - 1) != '&') {query.append('&');}}query.append("userId").append("=").append(baseDTO.getUserId()).append("&").append("userName").append("=").append(baseDTO.getUserName());try {URI newUri = UriComponentsBuilder.fromUri(uri).replaceQuery(query.toString()).build().encode().toUri();ServerHttpRequest request = exchange.getRequest().mutate().uri(newUri).build();return chain.filter(exchange.mutate().request(request).build());} catch (Exception e) {LOGGER.error("Invalid URI query: " + query.toString(), e);// 当前过滤器filter执行结束return chain.filter(exchange.mutate().request(builder.build()).build());}}
复制代码

Post请求 添加参数

请求内容为 application json

/*** post请求，添加参数* @param exchange* @param chain* @param baseDTO* @return*/private Mono addParameterForPostMethod(ServerWebExchange exchange, GatewayFilterChain chain, BaseDTO baseDTO) {ServerRequest serverRequest = new DefaultServerRequest(exchange);AtomicBoolean flag = new AtomicBoolean(false);Mono modifiedBody = serverRequest.bodyToMono(String.class).flatMap((o) -> {if(o.startsWith("[")){// body内容为数组，直接返回return Mono.just(o);}ObjectMapper objectMapper = new ObjectMapper();try {Map map = objectMapper.readValue(o, Map.class);map.put("userId", baseDTO.getUserId());map.put("userName", baseDTO.getUserName());String json = objectMapper.writeValueAsString(map);LOGGER.info("addParameterForPostMethod -> json = {}", json);return Mono.just(json);}catch (Exception e){e.printStackTrace();return Mono.just(o);}});BodyInserter bodyInserter = BodyInserters.fromPublisher(modifiedBody, String.class);CachedBodyOutputMessage outputMessage = new CachedBodyOutputMessage(exchange, exchange.getRequest().getHeaders());return bodyInserter.insert(outputMessage, new BodyInserterContext()).then(Mono.defer(() -> {ServerHttpRequestDecorator decorator = new ServerHttpRequestDecorator(exchange.getRequest()) {public HttpHeaders getHeaders() {HttpHeaders httpHeaders = new HttpHeaders();httpHeaders.putAll(super.getHeaders());httpHeaders.set("Transfer-Encoding", "chunked");return httpHeaders;}public Flux getBody() {return outputMessage.getBody();}};return chain.filter(exchange.mutate().request(decorator).build());}));}
复制代码

请求内容为 form data

/*** post请求，form data 添加参数* @param exchange* @param chain* @param baseDTO* @param builder* @return*/private Mono addParameterForFormData(ServerWebExchange exchange, GatewayFilterChain chain, BaseDTO baseDTO, ServerHttpRequest.Builder builder) {builder.header("userId", String.valueOf(baseDTO.getUserId()));try {builder.header("userName", URLEncoder.encode(String.valueOf(baseDTO.getUserName()), "UTF-8"));} catch (UnsupportedEncodingException e) {builder.header("userName", String.valueOf(baseDTO.getUserName()));}ServerHttpRequest serverHttpRequest = builder.build();HttpHeaders headers = serverHttpRequest.getHeaders();return chain.filter(exchange.mutate().request(serverHttpRequest).build());}
复制代码

返回数据处理

/*** 返回消息* @param exchange* @param data* @return*/private Mono illegalResponse(ServerWebExchange exchange, String data) {ServerHttpResponse originalResponse = exchange.getResponse();originalResponse.setStatusCode(HttpStatus.OK);originalResponse.getHeaders().add(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_UTF8_VALUE);byte[] response = data.getBytes(StandardCharsets.UTF_8);DataBuffer buffer = originalResponse.bufferFactory().wrap(response);return originalResponse.writeWith(Flux.just(buffer));}
复制代码

最终效果

上面描述，已实现将userId和userName两个属性，写入到request参数中。

在具体业务处理的服务模块，controller层的传参，只要继承包含userId和userName两个属性的BaseDTO类，就可以拿到该信息，用于实际的业务流程。

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