Spring Cloud Gateway 如何修改HTTP响应信息

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());
    }
    
    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;
        }
    }
}

flux = flux.doOnNext(data -> headers.setContentLength(data.readableByteCount()));

ServerHttpRequest newRequest = request.mutate().headers("key","value").path("/myPath").build();
ServerWebExchange newExchange = exchange.mutate().response(responseDecorator).build();

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;
 }
}

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;

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();
 }
}