Gateway 修改HTTP响应信息
实践Spring Cloud的过程中，使用Gateway作为路由组件，并且基于Gateway实现权限的验证、拦截、过滤，对于下游微服务的响应结果，我们总会有需要修改以统一数据格式，或者修改过滤用户没有权限看到的数据信息，这时候就需要有一个能够修改响应体的Filter。
Spring Cloud Gateway 版本为2.1.0
在当前版本，ModifyRequestBodyGatewayFilterFactory是官方提供的修改响应体的参考类，This filter is BETA and may be subject to change in a future release.，类的注释中说明这个类在以后版本中会改进，实际使用可以参考实现功能，但是性能影响较大，不过没有别的选择还是得选择这个。
官方文档：
实现
最终代码
先贴最终代码
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 |
public class ResponseDecryptionGlobalFilter implements GlobalFilter, Ordered { private static Logger log = LoggerFactory.getLogger(ResponseDecryptionGlobalFilter. class ); @Override public int getOrder() { // 控制在NettyWriteResponseFilter后执行 return NettyWriteResponseFilter.WRITE_RESPONSE_FILTER_ORDER - 1 ; } @Override public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) { return processResponse(exchange, chain); } private Mono<Void> processResponse(ServerWebExchange exchange, GatewayFilterChain chain) { // 路由中如果不需要过滤则不进行过滤 if (!BooleanUtils.isTrue()) { return chain.filter(exchange); } ServerHttpResponseDecorator responseDecorator = new ServerHttpResponseDecorator(exchange.getResponse()) { @Override public Mono<Void> writeWith(Publisher<? extends DataBuffer> body) { String originalResponseContentType = exchange.getAttribute(ORIGINAL_RESPONSE_CONTENT_TYPE_ATTR); HttpHeaders httpHeaders = new HttpHeaders(); httpHeaders.add(HttpHeaders.CONTENT_TYPE, originalResponseContentType); ResponseAdapter responseAdapter = new ResponseAdapter(body, httpHeaders); DefaultClientResponse clientResponse = new DefaultClientResponse(responseAdapter, ExchangeStrategies.withDefaults()); Mono<String> rawBody = clientResponse.bodyToMono(String. class ).map(s -> s); BodyInserter<Mono<String>, ReactiveHttpOutputMessage> bodyInserter = BodyInserters.fromPublisher(rawBody, String. class ); CachedBodyOutputMessage outputMessage = new CachedBodyOutputMessage(exchange, exchange.getResponse().getHeaders()); return bodyInserter.insert(outputMessage, new BodyInserterContext()) .then(Mono.defer(() -> { Flux<DataBuffer> messageBody = outputMessage.getBody(); Flux<DataBuffer> flux = messageBody.map(buffer -> { CharBuffer charBuffer = StandardCharsets.UTF_8.decode(buffer.asByteBuffer()); DataBufferUtils.release(buffer); // 将响应信息转化为字符串 String responseStr = charBuffer.toString(); if (StringUtils.isNotBlank(responseStr)) { try { JSONObject result = JSONObject.parseObject(responseStr); System.out.println(dataFilter(result)); if (result.containsKey( "data" )) { responseStr = dataFilter(result); } else { log.error( "响应结果序列化异常:{}" , responseStr); } } catch (JSONException e) { log.error( "响应结果序列化异常:{}" , responseStr); } } return getDelegate().bufferFactory().wrap(responseStr.getBytes(StandardCharsets.UTF_8)); }); HttpHeaders headers = getDelegate().getHeaders(); // 修改响应包的大小，不修改会因为包大小不同被浏览器丢掉 flux = flux.doOnNext(data -> headers.setContentLength(data.readableByteCount())); return getDelegate().writeWith(flux); })); } }; return chain.filter(exchange.mutate().response(responseDecorator).build()); } /** * 权限数据过滤 * * @param result * @return */ private String dataFilter(JSONObject result) { Object data = result.get( "data" ); return result.toJSONString(); } private class ResponseAdapter implements ClientHttpResponse { private final Flux<DataBuffer> flux; private final HttpHeaders headers; @SuppressWarnings ( "unchecked" ) private 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 ; } } } |
踩过的坑
响应体报文过大: 起初直接读取buffer的响应信息，包小的情况没有问题，但是包大了会抛出json无法转换异常，因为没能读取完整的响应内容，参考ModifyRequestBodyGatewayFilter，等待buffer全部读完再转为数组，然后执行处理。本质原因是底层的Reactor-Netty的数据块读取大小限制导致获取到的DataBuffer实例里面的数据是不完整的。 修改响应信息后，响应的ContentLength会发生变化，忘记修改response中的Content-Length长度，导致前端请求无法获取修改后的响应结果。
|
1 |
flux = flux.doOnNext(data -> headers.setContentLength(data.readableByteCount())); |
order值必须小于-1，因为覆盖返回响应体，自定义的GlobalFilter必须比NettyWriteResponseFilter处理完后执行。order越小越早进行处理，越晚处理响应结果。
理解ServerWebExchange
先看ServerWebExchange的注释：
Contract for an HTTP request-response interaction. Provides access to the HTTP request and response and also exposes additional server-side processing related properties and features such as request attributes.
翻译一下大概是：
ServerWebExchange是一个**HTTP请求-响应交互的契约。**提供对HTTP请求和响应的访问，并公开额外的服务器端处理相关属性和特性，如请求属性。
ServerWebExchange有点像Context的角色，我把它理解为http请求信息在Filter透传的容器，之所以称之为容器，因为它可以存储我们像放进去的数据。
注意：
ServerHttpRequest是一个只读类，因此需要通过下面例子的方法来进行修改，对于读多写少的场景，这种设计模式是值得借鉴的
|
1 2 |
ServerHttpRequest newRequest = request.mutate().headers( "key" , "value" ).path( "/myPath" ).build(); ServerWebExchange newExchange = exchange.mutate().response(responseDecorator).build(); |
Gateway 修改返回的响应体
问题描述：
在gateway中修改返回的响应体，在全局Filter中添加如下代码：
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 |
import org.springframework.core.Ordered; import org.springframework.cloud.gateway.filter.GlobalFilter; import org.springframework.cloud.gateway.filter.GatewayFilterChain; import org.springframework.stereotype.Component; import org.springframework.web.server.ServerWebExchange; import reactor.core.publisher.Mono; @Component public class RequestGlobalFilter implements GlobalFilter, Ordered { //...
@Override public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) { //... ResponseDecorator decorator = new ResponseDecorator(exchange.getResponse()); return chain.filter(exchange.mutate().response(decorator).build()); } @Override public int getOrder() { return - 1000 ; } } |
通过.response(decorator)设置一个响应装饰器（自定义），以下是装饰器具体实现：
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 |
import cn.hutool.json.JSONObject; import org.reactivestreams.Publisher; import org.springframework.core.io.buffer.DataBuffer; import org.springframework.core.io.buffer.DataBufferFactory; import org.springframework.core.io.buffer.DataBufferUtils; import org.springframework.core.io.buffer.DefaultDataBufferFactory; import org.springframework.http.server.reactive.ServerHttpResponse; import org.springframework.http.server.reactive.ServerHttpResponseDecorator; import reactor.core.publisher.Flux; import reactor.core.publisher.Mono; import java.nio.charset.Charset; /** * @author visy.wang * @desc 响应装饰器（重构响应体） */ public class ResponseDecorator extends ServerHttpResponseDecorator{ public ResponseDecorator(ServerHttpResponse delegate){ super (delegate); } @Override @SuppressWarnings (value = "unchecked" ) public Mono<Void> writeWith(Publisher<? extends DataBuffer> body) { if (body instanceof Flux) { Flux<DataBuffer> fluxBody = (Flux<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); // 释放掉内存
String bodyStr = new String(content, Charset.forName( "UTF-8" )); //修改响应体 bodyStr = modifyBody(bodyStr); getDelegate().getHeaders().setContentLength(bodyStr.getBytes().length); return bufferFactory().wrap(bodyStr.getBytes()); })); } return super .writeWith(body); } //重写这个函数即可 private String modifyBody(String jsonStr){ JSONObject json = new JSONObject(jsonStr); //TODO...修改响应体 return json.toString(); } } |
以上为个人经验，希望能给大家一个参考，也希望大家多多支持。
原文链接：https://blog.csdn.net/weiwoyonzhe/article/details/90814680
查看更多关于Spring Cloud Gateway 如何修改HTTP响应信息的详细内容...