How to get response body in Spring Gateway

问题

I'm working with spring cloud gateway filters and need to get response body to log it. I understand that it's problematic, as spring gateway is built on spring reactor, but nevertheless I'm looking for any way to do this.

Have global filter, code:

import org.reactivestreams.Publisher;
import org.reactivestreams.Subscriber;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.gateway.filter.GatewayFilter;
import org.springframework.cloud.gateway.filter.GatewayFilterChain;
import org.springframework.cloud.gateway.filter.GlobalFilter;
import org.springframework.cloud.gateway.filter.NettyWriteResponseFilter;
import org.springframework.cloud.gateway.filter.factory.rewrite.ModifyResponseBodyGatewayFilterFactory;
import org.springframework.cloud.gateway.filter.factory.rewrite.RewriteFunction;
import org.springframework.cloud.gateway.support.ServerWebExchangeUtils;
import org.springframework.core.Ordered;
import org.springframework.stereotype.Component;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Mono;

@Component
public class BodyRewrite implements RewriteFunction<byte[], byte[]> {

    @Override
    public Publisher<byte[]> apply(ServerWebExchange exchange, byte[] body) {
        System.out.println("-------------------------");
        System.out.println("       APPLY METHOD");
        System.out.println("-------------------------");
        String originalBody = body==null?"":new String(body);
        if (!ServerWebExchangeUtils.isAlreadyRouted(exchange)) {
            return Mono.just(originalBody.getBytes());
        } else {
            System.out.println("RESPONSE: " + originalBody);
        }

        return new Publisher<byte[]>() {
            @Override
            public void subscribe(Subscriber<? super byte[]> subscriber) {
                
            }
        };
    }
}

@Component
class ModifyResponseBodyFilter implements GlobalFilter, Ordered {
    @Autowired
    private ModifyResponseBodyGatewayFilterFactory modifyResponseBodyGatewayFilterFactory;
    @Autowired
    private BodyRewrite bodyRewrite;

    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        System.out.println("---------------------------");
        System.out.println("       GLOBAL FILTER");
        System.out.println("---------------------------");
        GatewayFilter delegate=modifyResponseBodyGatewayFilterFactory.apply(new ModifyResponseBodyGatewayFilterFactory.Config()
                .setRewriteFunction(byte[].class, byte[].class, bodyRewrite));
        return delegate.filter(exchange, chain);
    }

    @Override
    public int getOrder() {
        return NettyWriteResponseFilter.WRITE_RESPONSE_FILTER_ORDER-1;
    }

In the console I only get this output about 30 times in a row and no output with phrase "APPLY METHOD".

---------------------------
       GLOBAL FILTER
---------------------------

回答1:

im a rookie,both in English and Programing. here is a way but may not elegant: create a modifyResponseBodyFilter with the ModifyResponseBodyGatewayFilterFactory, and implement the RewriteFunction.

public class BodyRewrite implements RewriteFunction<byte[], byte[]> {
    @Override
    public Publisher<byte[]> apply(ServerWebExchange exchange, byte[] body) {
        String originalBody = body==null?"":new String(body);
        if (!ServerWebExchangeUtils.isAlreadyRouted(exchange)) {
            return Mono.just(originalBody.getBytes());
        } else {
        // its the reponse body when already routed
        }
    }
}

public class ModifyResponseBodyFilter implements GlobalFilter, Ordered {
    @Autowired
    private ModifyResponseBodyGatewayFilterFactory modifyResponseBodyGatewayFilterFactory;
    @Autowired
    private BodyRewrite bodyRewrite;

    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        GatewayFilter delegate=modifyResponseBodyGatewayFilterFactory.apply(new ModifyResponseBodyGatewayFilterFactory.Config()
                .setRewriteFunction(byte[].class, byte[].class, bodyRewrite));
        return delegate.filter(exchange, chain);
    }

    @Override
    public int getOrder() {
        return NettyWriteResponseFilter.WRITE_RESPONSE_FILTER_ORDER-1;
    }
}

来源：https://stackoverflow.com/questions/64439102/how-to-get-response-body-in-spring-gateway