Spring Cloud Gateway实战WebFlux解析请求体及抛出指定错误代码和信息

概述

基于Spring Cloud开发微服务时，使用Spring Cloud原生自带的Gateway作为网关，所有请求都需要经过网关服务转发。

为了防止恶意请求刷取数据，对于业务请求需要进行拦截，故而可在网关服务增加拦截过滤器。基于此，有如下源码：

@Slf4j
@Component
public class BlockListFilter extends AbstractGatewayFilterFactory {
	private static final String DIALOG_URI = "/dialog/nextQuestion";
    @Resource
    private AssessmentBlockListService assessmentBlockListService;
    @Lazy
    @Resource
    private RemoteUserService remoteUserService;
    @Lazy
    @Resource
    private RemoteRcService remoteRcService;
    @Lazy
    @Autowired
    private RemoteOAuthService remoteOAuthService;
    @Value("${blockListSwitch:true}")
    private Boolean blockListSwitch;

    @Override
    public GatewayFilter apply(Object config) {
        return (exchange, chain) -> {
            ServerHttpResponse response = exchange.getResponse();
            response.getHeaders().setContentType(MediaType.APPLICATION_JSON_UTF8);
            ServerHttpRequest serverHttpRequest = exchange.getRequest();
            String uri = serverHttpRequest.getURI().getPath();
            HttpHeaders httpHeaders = serverHttpRequest.getHeaders();
            // 只处理相关url
            if (blockListSwitch && StringUtils.equalsIgnoreCase(uri, DIALOG_URI)) {
                String token = httpHeaders.getFirst("Authorization");
                String pureToken = StringUtils.replaceIgnoreCase(token, "Bearer ", "");
                BaseUserInfo baseUserInfo = UserUtil.getBaseUserInfo(pureToken);
                if (baseUserInfo == null) {
                    log.warn("传入的token非法：{}", token);
                    return chain.filter(exchange);
                }
                // 从JWT token中解析用户信息(不含mobile等敏感信息)
                String channel = baseUserInfo.getChannel();
                String userKey = baseUserInfo.getUserkey();
                UserParam userParam = new UserParam();
                userParam.setKey(userKey);
                userParam.setChannel(channel);
                // Feign远程请求user服务获取mobile信息
                Response<UserAccountVO> userAccountResponse = remoteUserService.baseQuery(userParam);
                if (userAccountResponse.getCode() != 0) {
                    log.warn("未获取到userKey={}的用户信息！", userKey);
                    return chain.filter(exchange);
                }
                UserAccountVO userAccountVO = userAccountResponse.getData();
                log.info("blocklist filter user={}", JsonUtil.beanToJson(userAccountVO));
                String mobile = userAccountVO.getMobile();
                if (StringUtils.isNotBlank(userKey)) {
                	// 具体的拦截业务逻辑
                    this.process(uri, userKey, mobile, channel, pureToken);
                }
                return chain.filter(exchange);
            }
            return chain.filter(exchange);
        };
    }

	private String process(String uri, String userKey, String mobile, String channel, String token) {
        DetectUserDTO detectUserDTO = new DetectUserDTO();
        detectUserDTO.setChannel(channel);
        detectUserDTO.setMobile(mobile);
        detectUserDTO.setUserKey(userKey);
        detectUserDTO.setUri(uri);
        Response<DetectUserVO> detectUserVOResponse = remoteRcService.detectUser(detectUserDTO);
        if (detectUserVOResponse.getCode() != 0) {
            log.warn("mobile={} 风控接口返回异常：{}", mobile, JsonUtil.beanToJson(detectUserVOResponse));
            return null;
        }
        DetectUserVO detectUserVO = detectUserVOResponse.getData();
        if (detectUserVO.getIsInAllowList()) {
            log.info("在白名单中，放行");
        } else if (detectUserVO.getIsInBlockList()) {
            log.info("在黑名单中，拦截处理...");
            this.logout(token);
            return "当前手机号问诊次数已达今日上限！";
        }
        return null;
    }
    
    private void logout(String token) {
        // 强制下线,踢出登录态
        LogoutDto logoutDto = new LogoutDto();
        logoutDto.setToken(pureToken);
        remoteOAuthService.logout(logoutDto);
    }
}
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上面的代码只是实现：判断流量请求URL，进而判断用户是否触发风控黑名单机制，如果触发黑名单，则踢出登录态强制用户下线，即用户不能使用App。

需求

异常捕获

上面的踢出登录态做法过于简单粗暴，App有若干个功能模块，某些请求URL触发黑名单机制，就强制用户下线，不能使用App其他功能。应该允许用户使用除了触发黑名单模块的其他模块功能。当然，对于是否强制下线的交互设计，每个人有每个人的看法。

就我遇到的情况来细说，痛点在于，前端（所谓大前端概念，含iOS和安卓App）同学针对此种情况直接返回统一的错误页：【抱歉，请返回再试一次！】，并且这个页面没有任何UI设计，仅仅是前面提到的一句提示文案。用户看到这个文案，会重新登录（因为后端做了踢出登录态逻辑），App成功后经过网关校验，发现用户依旧触发黑名单，然后再次踢出登录态，陷入死循环。

基于此，做如下改造：不踢出登录态，可以继续使用其他模块功能，在使用某个触发黑名单机制的模块时后端返回错误码，前端弹窗提示【无法使用此功能】。

故而对上面的代码进行调整：

String msg = this.process(uri, userKey, mobile, channel, pureToken,);
if (StringUtils.isNotBlank(msg)) {
    return Mono.error(new CustomException(BlockTypeEnum.getCodeByMsg(msg), msg));
}
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本地启动Gateway网关服务，postman模拟请求，得到接口返回数据：

咦？怎么Code不是枚举类里定义的错误文案msg对应的错误码，而是500呢？

看代码，发现有个继承DefaultErrorWebExceptionHandler的JsonErrorWebExceptionHandler类，那这个类也需要调整：

@Slf4j
public class JsonErrorWebExceptionHandler extends DefaultErrorWebExceptionHandler {

    public JsonErrorWebExceptionHandler(ErrorAttributes errorAttributes,
                                        ResourceProperties resourceProperties,
                                        ErrorProperties errorProperties,
                                        ApplicationContext applicationContext) {
        super(errorAttributes, resourceProperties, errorProperties, applicationContext);
    }

    @Override
    protected Map<String, Object> getErrorAttributes(ServerRequest request, boolean includeStackTrace) {
        Map<String, Object> errorAttributes = new HashMap<>(8);
        Throwable error = super.getError(request);
        errorAttributes.put("message", error.getMessage());
        if (error instanceof CustomException) {
            errorAttributes.put("code", ((CustomException) error).getCode());
        } else {
            errorAttributes.put("code", HttpStatus.INTERNAL_SERVER_ERROR.value());
        }
        errorAttributes.put("method", request.methodName());
        errorAttributes.put("path", request.path());
        log.warn("网关异常,path:{},method:{},message:{}", request.path(), request.methodName(), error.getMessage());
        return errorAttributes;
    }

    @Override
    protected RouterFunction<ServerResponse> getRoutingFunction(ErrorAttributes errorAttributes) {
        return RouterFunctions.route(RequestPredicates.all(), this::renderErrorResponse);
    }

    @Override
    protected HttpStatus getHttpStatus(Map<String, Object> errorAttributes) {
        // 这里其实可以根据errorAttributes里面的属性定制HTTP响应码
        return HttpStatus.INTERNAL_SERVER_ERROR;
    }
}
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经过调整后，断点调试，万事大吉：

但是！！！

后来在和前端联调时才发现有点不对劲：

如上图，枚举类里有几个code，每个code都有对应的系统功能模块黑名单msg。之前没有注意到右上角的接口状态码是500，这个500表示请求未成功。也就是说，接口未成功，接口响应码是自定义的code也没啥用。status必须得是200、204、202这种才行。

总结一下：虽然使用Mono.error()返回业务自定义错误信息，但错误代码9996被转为500。

继续排查。找到下面参考2里的文章，做如下调整：

String msg = this.process(uri, userKey, mobile, channel, pureToken,);
if (StringUtils.isNotBlank(msg)) {
	// 对应200,表明接口请求是成功的,但是触发业务异常错误码
	exchange.getResponse().setStatusCode(HttpStatus.OK);
    return exchange.getResponse()
                        .writeWith(Flux.just(exchange.getResponse()
                                .bufferFactory()
                                .wrap(JSON.toJSONString(msg).getBytes())));
}
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调试结果，右上角的Status变成200：

注意看，Postman可以返回中文msg。

发布测试环境后，在Chrome浏览器里却发现返回数据乱码！？

IDEA调整截图如上没有乱码问题，console控制台打印也是正常：

乱码不是什么大问题，研发这么多年遇到无数次。继续排查，做如下调整解决问题：

return exchange.getResponse()
               .writeWith(Flux.just(exchange.getResponse()
               .bufferFactory().wrap(JSON.toJSONString(msg).getBytes(StandardCharsets.UTF_8))));
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获取请求体

前面提到，我们的App有几个功能模块，其中一个模块的请求全部是dialog/nextQuestion接口。用户恶意刷数据，多次请求此接口就会触发黑名单。但是在我们的交互设计上，又希望用户从其他功能模块切换到此功能时，可以请求一次此接口。那怎么判断是第一次呢？那就需要解析requestBody。

根据下面的参考1文章，增加如下代码：

public String resolveBodyForDialog(ServerHttpRequest serverHttpRequest) {
    String uri = serverHttpRequest.getURI().getPath();
    // 只有某些请求才解析
    if (!StringUtils.equalsAnyIgnoreCase(uri, "dialog/nextQuestion")) {
        return "";
    }
    StringBuilder sb = new StringBuilder();
    Flux<DataBuffer> body = serverHttpRequest.getBody();
    body.subscribe(buffer -> {
        byte[] bytes = new byte[buffer.readableByteCount()];
        buffer.read(bytes);
        DataBufferUtils.release(buffer);
        String bodyString = new String(bytes, StandardCharsets.UTF_8);
        sb.append(bodyString);
    });
    return sb.toString();
}
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本地调试时没有问题，可以获取到requestBody：

但是测试环境却又问题：

详细的错误日志：

500 Server Error for HTTP POST "/api/open/dialog/nextQuestion"
io.netty.handler.codec.EncoderException: io.netty.util.IllegalReferenceCountException: refCnt: 0, decrement: 1
at io.netty.handler.codec.MessageToMessageEncoder.write(MessageToMessageEncoder.java:107)
at io.netty.channel.CombinedChannelDuplexHandler.write(CombinedChannelDuplexHandler.java:348)
at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:716)
at io.netty.channel.AbstractChannelHandlerContext.invokeWrite(AbstractChannelHandlerContext.java:708)
at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:791)
at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:701)
at reactor.netty.channel.MonoSendMany$SendManyInner.run(MonoSendMany.java:286)
at reactor.netty.channel.MonoSendMany$SendManyInner.trySchedule(MonoSendMany.java:368)
at reactor.netty.channel.MonoSendMany$SendManyInner.onSubscribe(MonoSendMany.java:221)
at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onSubscribe(FluxMapFuseable.java:90)
at reactor.core.publisher.FluxContextStart$ContextStartSubscriber.onSubscribe(FluxContextStart.java:97)
at reactor.core.publisher.MonoJust.subscribe(MonoJust.java:54)
at reactor.core.publisher.MonoSubscriberContext.subscribe(MonoSubscriberContext.java:47)
at reactor.core.publisher.FluxSourceMonoFuseable.subscribe(FluxSourceMonoFuseable.java:38)
at reactor.core.publisher.FluxMapFuseable.subscribe(FluxMapFuseable.java:63)
at reactor.core.publisher.Flux.subscribe(Flux.java:7921)
at reactor.netty.channel.MonoSendMany.subscribe(MonoSendMany.java:81)
at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.drain(MonoIgnoreThen.java:153)
at reactor.core.publisher.MonoIgnoreThen.subscribe(MonoIgnoreThen.java:56)
at reactor.core.publisher.Mono.subscribe(Mono.java:3848)
at reactor.netty.NettyOutbound.subscribe(NettyOutbound.java:305)
at reactor.core.publisher.MonoSource.subscribe(MonoSource.java:51)
at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52)
at reactor.netty.http.client.HttpClientConnect$HttpIOHandlerObserver.onStateChange(HttpClientConnect.java:441)
at reactor.netty.ReactorNetty$CompositeConnectionObserver.onStateChange(ReactorNetty.java:470)
at reactor.netty.resources.PooledConnectionProvider$DisposableAcquire.onStateChange(PooledConnectionProvider.java:512)
at reactor.netty.resources.PooledConnectionProvider$PooledConnection.onStateChange(PooledConnectionProvider.java:451)
at reactor.netty.channel.ChannelOperationsHandler.channelActive(ChannelOperationsHandler.java:62)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelActive(AbstractChannelHandlerContext.java:225)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelActive(AbstractChannelHandlerContext.java:211)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelActive(AbstractChannelHandlerContext.java:204)
at io.netty.channel.CombinedChannelDuplexHandler$DelegatingChannelHandlerContext.fireChannelActive(CombinedChannelDuplexHandler.java:414)
at io.netty.channel.ChannelInboundHandlerAdapter.channelActive(ChannelInboundHandlerAdapter.java:69)
at io.netty.channel.CombinedChannelDuplexHandler.channelActive(CombinedChannelDuplexHandler.java:213)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelActive(AbstractChannelHandlerContext.java:225)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelActive(AbstractChannelHandlerContext.java:211)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelActive(AbstractChannelHandlerContext.java:204)
at io.netty.channel.DefaultChannelPipeline$HeadContext.channelActive(DefaultChannelPipeline.java:1396)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelActive(AbstractChannelHandlerContext.java:225)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelActive(AbstractChannelHandlerContext.java:211)
at io.netty.channel.DefaultChannelPipeline.fireChannelActive(DefaultChannelPipeline.java:906)
at io.netty.channel.epoll.AbstractEpollChannel$AbstractEpollUnsafe.fulfillConnectPromise(AbstractEpollChannel.java:618)
at io.netty.channel.epoll.AbstractEpollChannel$AbstractEpollUnsafe.finishConnect(AbstractEpollChannel.java:651)
at io.netty.channel.epoll.AbstractEpollChannel$AbstractEpollUnsafe.epollOutReady(AbstractEpollChannel.java:527)
at io.netty.channel.epoll.EpollEventLoop.processReady(EpollEventLoop.java:422)
at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:333)
at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:906)
at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
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具体研究这篇文章，做如下调整：

String uri = serverHttpRequest.getURI().getPath();
// 只有某些请求才解析
if (!StringUtils.equalsAnyIgnoreCase(uri, DIALOG_URI)) {
    return "";
}
Flux<DataBuffer> body = serverHttpRequest.getBody();
AtomicReference<String> bodyRef = new AtomicReference<>();
body.subscribe(buffer -> {
    CharBuffer charBuffer = StandardCharsets.UTF_8.decode(buffer.asByteBuffer());
    bodyRef.set(charBuffer.toString());
});
return bodyRef.get();
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上面的报错消失。问题虽然是解决，但是不明就里。

后面又发现一个乱码问题，针对如下requestBody：

{
  "stateId": "DASHBOARD",
  "answer": {
    "transitionId": "GET_HEALTH_ADVICE",
    "label": "开始评估症状"
  }
}
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bodyRef.get()获取到的中文数据乱码。参考3，解决方法：

String encoding = System.getProperty("file.encoding");
CharBuffer charBuffer = Charset.forName(encoding).decode(buffer.asByteBuffer());
bodyRef.set(charBuffer.toString());
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参考

• Spring Cloud Gateway读取RequestBody数据
• 使用Spring Cloud-Gateway WebFlux抛出指定错误代码和信息
• 从String获得ByteBuffer、从ByteBuffer获得CharBuffer的正确姿势