获取SpringCloud gateway响应的response的值，记录踩坑

最近在做网关改造，想要通过Gateway过滤器获取ResponseBody的值，查看了网上的帖子和官网内容：

帖子：https://cloud.tencent.com/developer/article/1384111

官网：https://github.com/spring-cloud/spring-cloud-gateway/blob/master/spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/filter/factory/rewrite/ModifyResponseBodyGatewayFilterFactory.java

但在实际操作中却掉坑里了，居然不起作用，就是不进重写但writeWith方法

 @Component

 @Order(-2)

 public class EncryptResponseBodyFilter implements GlobalFilter {

     @Override

     public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {

         ServerHttpResponse originalResponse = exchange.getResponse();

         DataBufferFactory bufferFactory = originalResponse.bufferFactory();

         ServerHttpResponseDecorator response = new ServerHttpResponseDecorator(originalResponse) {

             @Override

             public Mono<Void> writeWith(Publisher<? extends DataBuffer> body) {

                 if (getStatusCode().equals(HttpStatus.OK) && body instanceof Flux) {

                     Flux<? extends DataBuffer> fluxBody = Flux.from(body);

                     return super.writeWith(fluxBody.map(dataBuffer -> {

                         // probably should reuse buffers

                         byte[] content = new byte[dataBuffer.readableByteCount()];

                         dataBuffer.read(content);

                         //释放掉内存

                         DataBufferUtils.release(dataBuffer);

                         String s = new String(content, Charset.forName("UTF-8"));

                         //TODO，s就是response的值，想修改、查看就随意而为了

                         byte[] uppedContent = s.getBytes();

                         return bufferFactory.wrap(uppedContent);

                     }));

                 }

                 return super.writeWith(body);

             }

             @Override

             public Mono<Void> writeAndFlushWith(Publisher<? extends Publisher<? extends DataBuffer>> body) {

                 return writeWith(Flux.from(body)

                         .flatMapSequential(p -> p));

             }

         };         return chain.filter(exchange.mutate().response(response).build());

     }

后来与帖子和官网代码内容对比，只有Order的方式不同，就换了下实现Ordered重写getOrder方法方式试试，结果出乎意料，居然好用了！！！

真的是绞尽脑汁啊，浪费了不少时间。。。。

后来发现响应数据存在分段响应的问题：

参考：https://blog.csdn.net/fayeyiwang/article/details/9137// JSON响应数据拼接容器

private static Joiner joiner = Joiner.on("");

@Override

public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {

    ServerHttpResponse originalResponse = exchange.getResponse();

    DataBufferFactory bufferFactory = originalResponse.bufferFactory();

    ServerHttpResponseDecorator response = new ServerHttpResponseDecorator(originalResponse) {

        @Override

        public Mono<Void> writeWith(Publisher<? extends DataBuffer> body) {

            if (getStatusCode().equals(HttpStatus.OK) && body instanceof Flux) {

                // 获取ContentType，判断是否返回JSON格式数据

                String originalResponseContentType = exchange.getAttribute(ORIGINAL_RESPONSE_CONTENT_TYPE_ATTR);

                if(StringUtils.isNotBlank(originalResponseContentType) && originalResponseContentType.contains("application/json")) {

                   Flux<? extends DataBuffer> fluxBody = Flux.from(body);

                   return super.writeWith(fluxBody.buffer().map(dataBuffers -> {//解决返回体分段传输

                      List<String> list = Lists.newArrayList();

                      dataBuffers.forEach(dataBuffer -> {

                         try {

                            byte[] content = new byte[dataBuffer.readableByteCount()];

                            dataBuffer.read(content);

                            DataBufferUtils.release(dataBuffer);

                            list.add(new String(content, "utf-8"));

                         } catch (Exception e) {

                            logger.info("动态加载API加密规则失败，失败原因：{}", Throwables.getStackTraceAsString(e));

                         }

                       });

                       String responseData = joiner.join(list);

                       // 二次处理（加密/过滤等）如果不需要做二次处理可直接跳过下行

                       responseData = beforeBodyWriteInternal(responseData, exchange.getRequest());

                       byte[] uppedContent = new String(responseData.getBytes(), Charset.forName("UTF-8")).getBytes();

                       originalResponse.getHeaders().setContentLength(uppedContent.length);

                       return bufferFactory.wrap(uppedContent);

                    }));

                 }

            }

            return super.writeWith(body);

        }

        @Override

        public Mono<Void> writeAndFlushWith(Publisher<? extends Publisher<? extends DataBuffer>> body) {

            return writeWith(Flux.from(body).flatMapSequential(p -> p));
        }

    };

    return chain.filter(exchange.mutate().response(response).build());
}