如何修改response的header和body
如何修改response的header和body修改header修改statusCode修改body如何修改response的header和body
shenyu是基于 webflux 的响应式编程项目，由于之前没有接触过，我在开发 modifyResponse插件的时候，开始有点摸不着头脑，然后大佬推荐了一个链接：
https://htmlpreview.github.io/?/get-set/reactor-core/blob/master-zh/src/docs/index.html
看完我对响应性编程有了初步的了解。
修改header
1.获取HttpHeaders
ServerHttpResponse response = exchange.getResponse();HttpHeaders httpHeaders = response.getHeaders();
2.HttpHeaders提供了 add、set、addAll、remove 等函数来操作数据。
if (Objects.nonNull(modifyResponseRuleHandle.getAddHeaders()) && MapUtils.isNotEmpty(modifyResponseRuleHandle.getAddHeaders())) {Map<String, String> addHeaderMap = modifyResponseRuleHandle.getAddHeaders();addHeaderMap.entrySet().stream().forEach(a -> httpHeaders.add(a.getKey(), a.getValue()));}if (Objects.nonNull(modifyResponseRuleHandle.getSetHeaders()) && MapUtils.isNotEmpty(modifyResponseRuleHandle.getSetHeaders())) {Map<String, String> setHeaderMap = modifyResponseRuleHandle.getSetHeaders();setHeaderMap.entrySet().stream().forEach(a -> httpHeaders.set(a.getKey(), a.getValue()));}if (Objects.nonNull(modifyResponseRuleHandle.getReplaceHeaderKeys()) && MapUtils.isNotEmpty(modifyResponseRuleHandle.getReplaceHeaderKeys())) {Map<String, String> replaceHeaderMap = modifyResponseRuleHandle.getReplaceHeaderKeys();replaceHeaderMap.entrySet().stream().forEach(a -> {httpHeaders.addAll(a.getValue(), httpHeaders.get(a.getKey()));httpHeaders.remove(a.getKey());});}if (Objects.nonNull(modifyResponseRuleHandle.getRemoveHeaderKeys()) && !CollectionUtils.isEmpty(modifyResponseRuleHandle.getRemoveHeaderKeys())) {Set<String> removeHeaderList = modifyResponseRuleHandle.getRemoveHeaderKeys();removeHeaderList.stream().forEach(a -> httpHeaders.remove(a));}
修改statusCode
1.获取ClientResponse
ClientResponse clientResponse = exchange.getAttribute(Constants.CLIENT_RESPONSE_ATTR);
2.设置code
response.setStatusCode(HttpStatus.valueOf(modifyResponseRuleHandle.getStatusCode()));
修改body
这一步是最难的，我也是请教了大佬才解决的问题。
关键点是自定义一个类 ModifyServerHttpResponse 继承 ServerHttpResponseDecorator ，然后重写 writeWith 函数。然后从 DataBuffer 里读出 body 的内容，修改完再写回去。
1.执行入口
doExecute（）最后调用 ModifyServerHttpResponse 的初始化
return chain.execute(exchange.mutate().response(new ModifyServerHttpResponse(exchange, modifyResponseRuleHandle)).build());
2.WebClientMessageWriter 在 writeWith 的时候，会走到子类的重写函数里
return response.writeWith(clientResponse.body(BodyExtractors.toDataBuffers())).doOnCancel(() -> clean(exchange));
3.重写 body ，这一块有参考 SpringCloudGateway
public Mono<Void> writeWith(@NonNull final Publisher<? extends DataBuffer> body) {HttpHeaders httpHeaders = new HttpHeaders();httpHeaders.setContentType(MediaType.APPLICATION_JSON);//重新生成responseClientResponse clientResponse = prepareClientResponse(body, httpHeaders);//修改body里的内容，并返回Mono字节流Mono<byte[]> modifiedBody = clientResponse.bodyToMono(byte[].class).flatMap(originalBody -> Mono.just(updateResponse(originalBody)));//生成BodyInserterBodyInserter<Mono<byte[]>, ReactiveHttpOutputMessage> bodyInserter =BodyInserters.fromPublisher(modifiedBody, byte[].class);//保存body的信息CachedBodyOutputMessage outputMessage = new CachedBodyOutputMessage(exchange,exchange.getResponse().getHeaders());//把body写回resposne return bodyInserter.insert(outputMessage, new BodyInserterContext()).then(Mono.defer(() -> {Mono<DataBuffer> messageBody = DataBufferUtils.join(outputMessage.getBody());HttpHeaders headers = getDelegate().getHeaders();if (!headers.containsKey(HttpHeaders.TRANSFER_ENCODING)|| headers.containsKey(HttpHeaders.CONTENT_LENGTH)) {//重写body的长度messageBody = messageBody.doOnNext(data -> headers.setContentLength(data.readableByteCount()));}return getDelegate().writeWith(messageBody);}));}
因为body的内容可能是多层级的，例如
{"code":0,"msg":"sucess","data":{"nameInfo":{"name":"test"},"body":{"age":"18"}}}
所以修改 body 内容，用的是 JsonPath，需要在插件的 pom 文件里加上下面的依赖
<dependency><groupId>com.jayway.jsonpath</groupId><artifactId>json-path</artifactId><version>2.4.0</version></dependency>
具体代码，可以参考 shenyu 的代码仓库 /apache/incubator-shenyu
里面的 shenyu-plugin-modify-reponse 模块
