目录

1、问题背景

2、分析源码过程

3、解决办法

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最近在测试环境spring cloud gateway突然出现了异常，在这里记录一下，直接上干货

1、问题背景

测试环境spring cloud gateway遇到以下异常

DataBufferLimitException: Exceeded limit on max bytes to buffer : 262144（超出了缓冲区的最大字节数限制）

乍一看，问题很简单啊，通过配置加大缓存区不就行了啊，于是就在application.yml加了以下配置

#将缓存区设置为2m
spring:
  codec:
    max-in-memory-size: 2MB

可是问题又出现了，通过调试发现配置的max-in-memory-size在程序启动初始化确实是生效的。但是有业务调用的时候，此参数的接收值为null,maxInMemorySize还是读取的默认值（256K）。

那咋整，只能从源码入手了。

2、分析源码过程

通过异常日志，可以定位到异常位置

后来发现我们自定义的拦截器获取body的信息是获取方式，代码如下

因为HandlerStrategies.withDefaults() 是每次都需要重新创建对象，并非是spring注入的对象，所以每次获取的都是默认值，导致配置不生效。

3、解决办法

在我们自定的拦截器中注入ServerCodecConfigurer类，通过该类获取配置。这样获取到的就是我们在application.yml中配置的缓存区配置的字节数限制了。

具体代码：

@Component
@Slf4j
public class RequestFilter implements GlobalFilter, Ordered {

    @Override
    public int getOrder() {
        return OrderedConstant.HIGHEST_PRECEDENCE;
    }
    //手动注入ServerCodecConfigurer
    @Autowired
    ServerCodecConfigurer codecConfigurer;
    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        StopWatch stopWatch = new StopWatch();
        stopWatch.start();
        long startTime = System.currentTimeMillis();
        try {

            final Log logDTO = new Log();
            ServerHttpRequest request = exchange.getRequest();
            // 设置X-Request-Id
            AtomicReference<String> requestId = new AtomicReference<>(GenerateIdUtils.requestIdWithUUID());
            Consumer<HttpHeaders> httpHeadersConsumer = httpHeaders -> {
                String headerRequestId = request.getHeaders().getFirst(HeaderConstant.REQUEST_ID);
                if (!Strings.isNullOrEmpty(headerRequestId)) {
                    requestId.set(headerRequestId);
                }
                logDTO.setRequestId(requestId.get());
                httpHeaders.set(HeaderConstant.REQUEST_ID, requestId.get());
                httpHeaders.set(HeaderConstant.START_TIME_KEY, String.valueOf(startTime));
            };
            // codecConfigurer.getReaders()获取pplication.yml中配置的缓存区配置的字节数
            ServerRequest serverRequest = ServerRequest.create(exchange,
                    codecConfigurer.getReaders());

            URI requestUri = request.getURI();
            String uriQuery = requestUri.getQuery();
            String url = requestUri.getPath() + (!Strings.isNullOrEmpty(uriQuery) ? "?" + uriQuery : "");
            HttpHeaders headers = request.getHeaders();
            MediaType mediaType = headers.getContentType();
            String method = request.getMethodValue().toUpperCase();


            // 原始请求体
            final AtomicReference<String> requestBody = new AtomicReference<>();
            final AtomicBoolean newBody = new AtomicBoolean(false);
            if (mediaType != null && LogHelper.isUploadFile(mediaType)) {
                requestBody.set("上传文件");
            } else {
                if (method.equals("GET")) {
                    if (!Strings.isNullOrEmpty(uriQuery)) {
                        requestBody.set(uriQuery);
                    }
                } else {
                    newBody.set(true);
                }
            }
            logDTO.setLevel(Log.LEVEL.INFO);
            logDTO.setRequestUrl(url);
            logDTO.setRequestBody(requestBody.get());
            logDTO.setRequestMethod(method);
            logDTO.setIp(IpUtils.getClientIp(request));

            ServerHttpRequest serverHttpRequest = exchange.getRequest().mutate().headers(httpHeadersConsumer).build();
            ServerWebExchange build = exchange.mutate().request(serverHttpRequest).build();
            return build.getSession().flatMap(webSession -> {
                logDTO.setSessionId(webSession.getId());
                if (newBody.get() && headers.getContentLength() > 0) {
                    Mono<String> bodyToMono = serverRequest.bodyToMono(String.class);
                    return bodyToMono.flatMap(reqBody -> {
                        logDTO.setRequestBody(reqBody);
                        // 重写原始请求
                        ServerHttpRequestDecorator requestDecorator = new ServerHttpRequestDecorator(exchange.getRequest()) {
                            @Override
                            public Flux<DataBuffer> getBody() {
                                NettyDataBufferFactory nettyDataBufferFactory = new NettyDataBufferFactory(new UnpooledByteBufAllocator(false));
                                DataBuffer bodyDataBuffer = nettyDataBufferFactory.wrap(reqBody.getBytes());
                                return Flux.just(bodyDataBuffer);
                            }
                        };
                        return chain.filter(exchange.mutate()
                                .request(requestDecorator)
                                .build()).then(LogHelper.doRecord(logDTO));
                    });
                } else {
                    return chain.filter(exchange).then(LogHelper.doRecord(logDTO));
                }
            });

        } catch (Exception e) {
            log.error("请求日志打印出现异常", e);
            return chain.filter(exchange);
        }
    }

}