I've implemented a Post filter in the spring cloud gateway. But I need the readable format (JSON Format of response body) before sending it to UI. I'm getting exchange.getResponse(). (when i printed in console: org.springframework.http.server.reactive.ReactorServerHttpResponse@3891d61a) But it is in the reactive object. I can't able to see the actual original response which is coming from API to post filter. I've searched numerous stackoverflow topics but couldn't get an actual solution. Please assist...
2 Answers
you can extract/read/modify/manipulate the request and response and their headers with the help of ServerHttpRequestDecorator & ServerHttpResponseDecorator see below
Note: i implemented GatewayFilter because i have this logic in gateway service level, if you want to modify at micro service level you can use WebFilter
import lombok.extern.log4j.Log4j2; import org.apache.commons.io.IOUtils; import org.reactivestreams.Publisher; import org.springframework.cloud.gateway.filter.GatewayFilter; import org.springframework.cloud.gateway.filter.GatewayFilterChain; import org.springframework.context.annotation.Configuration; import org.springframework.core.Ordered; import org.springframework.core.io.buffer.DataBuffer; import org.springframework.core.io.buffer.DataBufferFactory; import org.springframework.core.io.buffer.DefaultDataBuffer; import org.springframework.core.io.buffer.DefaultDataBufferFactory; import org.springframework.http.server.reactive.ServerHttpRequest; import org.springframework.http.server.reactive.ServerHttpRequestDecorator; import org.springframework.http.server.reactive.ServerHttpResponse; import org.springframework.http.server.reactive.ServerHttpResponseDecorator; import org.springframework.web.server.ServerWebExchange; import reactor.core.publisher.Flux; import reactor.core.publisher.Mono; import reactor.core.scheduler.Schedulers; import java.io.ByteArrayOutputStream; import java.nio.channels.Channels; import java.nio.charset.StandardCharsets; @Configuration @Log4j2 public class RequestResponseModifyFilter implements GatewayFilter/WebFilter, Ordered { @Override public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) { String path = exchange.getRequest().getPath().toString(); ServerHttpResponse response = exchange.getResponse(); ServerHttpRequest request = exchange.getRequest(); DataBufferFactory dataBufferFactory = response.bufferFactory(); // log the request body ServerHttpRequest decoratedRequest = getDecoratedRequest(request); // log the response body ServerHttpResponseDecorator decoratedResponse = getDecoratedResponse(path, response, request, dataBufferFactory); return chain.filter(exchange.mutate().request(decoratedRequest).response(decoratedResponse).build()); } private ServerHttpResponseDecorator getDecoratedResponse(String path, ServerHttpResponse response, ServerHttpRequest request, DataBufferFactory dataBufferFactory) { return new ServerHttpResponseDecorator(response) { @Override public Mono<Void> writeWith(final Publisher<? extends DataBuffer> body) { if (body instanceof Flux) { Flux<? extends DataBuffer> fluxBody = (Flux<? extends DataBuffer>) body; return super.writeWith(fluxBody.buffer().map(dataBuffers -> { DefaultDataBuffer joinedBuffers = new DefaultDataBufferFactory().join(dataBuffers); byte[] content = new byte[joinedBuffers.readableByteCount()]; joinedBuffers.read(content); String responseBody = new String(content, StandardCharsets.UTF_8);//MODIFY RESPONSE and Return the Modified response log.debug("requestId: {}, method: {}, url: {}, \nresponse body :{}", request.getId(), request.getMethodValue(), request.getURI(), responseBody); return dataBufferFactory.wrap(responseBody.getBytes()); })).onErrorResume(err -> { log.error("error while decorating Response: {}",err.getMessage()); return Mono.empty(); }); } return super.writeWith(body); } }; } private ServerHttpRequest getDecoratedRequest(ServerHttpRequest request) { return new ServerHttpRequestDecorator(request) { @Override public Flux<DataBuffer> getBody() { log.debug("requestId: {}, method: {} , url: {}", request.getId(), request.getMethodValue(), request.getURI()); return super.getBody().publishOn(Schedulers.boundedElastic()).doOnNext(dataBuffer -> { try (ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream()) { Channels.newChannel(byteArrayOutputStream).write(dataBuffer.asByteBuffer().asReadOnlyBuffer()); String requestBody = IOUtils.toString(byteArrayOutputStream.toByteArray(), StandardCharsets.UTF_8.toString());//MODIFY REQUEST and Return the Modified request log.debug("for requestId: {}, request body :{}", request.getId(), requestBody); } catch (Exception e) { log.error(e.getMessage()); } }); } }; } @Override public int getOrder() { return -2;} } https://github.com/einsteinarbert/spring-webfux-response-logging Beware about Security Chain, maybe that filter will override your filter.
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