SpringCloud Gateway拦截器遇到的小坑汇总

很多朋友在使用SpringCloudGateway的时候可能都碰到过以下几个问题

SpringCloudGateway中如何读取Post请求体

    private BodyInserter getBodyInserter(ServerWebExchange exchange) {        ServerRequest serverRequest = new DefaultServerRequest(exchange);        Mono<String> modifiedBody = serverRequest.bodyToMono(String.class)                .flatMap(body -> {                   //这里的body就是Post的请求体                });        BodyInserter bodyInserter = BodyInserters.fromPublisher(modifiedBody, String.class);        return bodyInserter;    }

SpringCloudGateway中Post请求参数只能读取一次

这是因为Gateway默认使用的是SpringWebflux，解决这个问题需要容重新构造一个request来替换原先的request

HttpHeaders headers=new HttpHeaders();        CachedBodyOutputMessage outputMessage = new CachedBodyOutputMessage(exchange, headers);        ServerHttpRequestDecorator decorator = this.getServerHttpRequestDecorator(exchange,outputMessage);       ServerHttpRequestDecorator decorator = new ServerHttpRequestDecorator(                exchange.getRequest()) {            @Override            public Flux<DataBuffer> getBody() {                return outputMessage.getBody();            }        };

当ServerHttpRequestDecorator构建完成之后需要在拦截器中使用如下方法替换原先的request

chain.filter(exchange.mutate().request(decorator).build());

SpringCloudGateway中如何读取后段服务的返回数据

与上方替换request的思路一致，替换response即可

private ServerHttpResponse getServerHttpResponse(ServerWebExchange exchange) {        ServerHttpResponse originalResponse = exchange.getResponse();        DataBufferFactory bufferFactory = originalResponse.bufferFactory();        ServerHttpResponseDecorator decoratedResponse = new ServerHttpResponseDecorator(originalResponse) {

            @Override            public Mono<Void> writeWith(Publisher<? extends DataBuffer> body) {
                Flux<DataBuffer> flux = null;                if (body instanceof Mono) {                    Mono<? extends DataBuffer> mono = (Mono<? extends DataBuffer>) body;                    body = mono.flux();
                }                if (body instanceof Flux) {                    flux = (Flux<DataBuffer>) body;                    return super.writeWith(flux.buffer().map(dataBuffers -> {                        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();                        dataBuffers.forEach(i -> {                            byte[] array = new byte[i.readableByteCount()];                            i.read(array);                            DataBufferUtils.release(i);                            outputStream.write(array, 0, array.length);                        });                        String result = outputStream.toString();                        try {                            if (outputStream != null) {                                outputStream.close();                            }                        } catch (IOException e) {                            e.printStackTrace();                        }                        log.info("后端返回数据：{}", result);                        return bufferFactory.wrap(result.getBytes());                    }));                }
                log.info("降级处理返回数据：{}" + body);                return super.writeWith(body);            }
        };        return decoratedResponse;    }

上方是获取新的response，获取到新的之后和之前的套路一样，这样操作：

return chain.filter(exchange.mutate().request(decorator).response(decoratedResponse).build());

可能有的同学会碰到即使按照我上述的方法重写了response但是也无法读取到返回数据，这个原因可能是因为拦截器的优先级配置有问题，只需要实现Ordered接口并且重写getOrder方法，然后设置优先级小于-1即可

   @Override    public int getOrder() {        return -2;    }

 

 

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