如何在Spring Gateway中获取响应体

Question

我正在使用spring cloud gateway filters，需要获取response body来记录它。我知道这是有问题的，因为spring gateway是建立在spring reactor之上的，但尽管如此，我还是在寻找任何方法来做到这一点。

拥有全局过滤器，代码：

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;
    }

在控制台中，我只能得到一行大约30次的输出，并且没有包含短语"APPLY METHOD“的输出。

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

Answer 1

我是一个新手，无论是英语还是编程。这里有一种方法，但可能并不优雅:使用ModifyResponseBodyGatewayFilterFactory创建一个modifyResponseBodyFilter，并实现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;
    }
}