spring cloud gateway获取请求的真实地址

拼搏现实的明天。 2022-05-13 10:12 263阅读 0赞

在使用spring cloud gateway的时候，路由一般配置为服务名 例如 lb://BASE-API-WEB/xxx/bbb 路径，我们无从知道，他真正路由到什么地方去了。

经过查看源码我发现了，

org.springframework.cloud.gateway.filter.LoadBalancerClientFilter

这个filter中 对lb请求进行了处理，转换成真正的url地址。

核心方法如下

public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
           //lb下的url
     URI url = (URI)exchange.getAttribute(ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR);
            String schemePrefix = (String)exchange.getAttribute(ServerWebExchangeUtils.GATEWAY_SCHEME_PREFIX_ATTR);
            if (url == null || !"lb".equals(url.getScheme()) && !"lb".equals(schemePrefix)) {
                return chain.filter(exchange);
            } else {
                ServerWebExchangeUtils.addOriginalRequestUrl(exchange, url);
                log.trace("LoadBalancerClientFilter url before: " + url);
                ServiceInstance instance = this.loadBalancer.choose(url.getHost());
                if (instance == null) {
                    throw new NotFoundException("Unable to find instance for " + url.getHost());
                } else {
                    URI uri = exchange.getRequest().getURI();
                    String overrideScheme = null;
                    if (schemePrefix != null) {
                        overrideScheme = url.getScheme();
                    }
                    //真实的url
                    URI requestUrl = this.loadBalancer.reconstructURI(new LoadBalancerClientFilter.DelegatingServiceInstance(instance, overrideScheme), uri);
                    log.trace("LoadBalancerClientFilter url chosen: " + requestUrl);
                    exchange.getAttributes().put(ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR, requestUrl);
                    return chain.filter(exchange);
                }
            }
        }

其实，spring cloud gateway 已经打印了日志，但是默认的他是trace级别的，我们常用的日志级别是info级别，所有他不会打印，这就导致了我们在日志中看不到真实的url地址

以下是解决办法：

1.在配置文件中设置org.springframework.cloud.gateway.filter.LoadBalancerClientFilter的日志级别

logging.level.org.springframework.cloud.gateway.filter.LoadBalancerClientFilter=TRACE

注意 这里的配置一定要在

logging.level.org.springframework之后配置 不然会覆盖

2.重写LoadBalancerClientFilter 建立org.springframework.cloud.gateway.filter包 将 类重写 spingboot默认会从本项目中加载类，原先的类就被弃用了。

3.继承LoadBalancerClientFilter 重写filter方法，将日志级别改为info即可

@Override
        public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
            URI url = exchange.getAttribute(ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR);
            String schemePrefix = exchange.getAttribute(ServerWebExchangeUtils.GATEWAY_SCHEME_PREFIX_ATTR);
            if (url == null || !"lb".equals(url.getScheme()) && !"lb".equals(schemePrefix)) {
                return chain.filter(exchange);
            } else {
                ServerWebExchangeUtils.addOriginalRequestUrl(exchange, url);
                ServiceInstance instance = this.loadBalancer.choose(url.getHost());
                if (instance == null) {
                    throw new NotFoundException("Unable to find instance for " + url.getHost());
                } else {
                    URI uri = exchange.getRequest().getURI();
                    String overrideScheme = null;
                    if (schemePrefix != null) {
                        overrideScheme = url.getScheme();
                    }
    
                    URI requestUrl = this.loadBalancer.reconstructURI(new LoadBalancerClientFilterBean.DelegatingServiceInstance(instance, overrideScheme), uri);
                    logger.info("before url = {} , url chosen = {} " ,url, requestUrl);
                    exchange.getAttributes().put(ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR, requestUrl);
                    return chain.filter(exchange);
                }
            }
        }

最终效果如下 ：

![70][]

[70]: /images/20220513/96b7a251b03541c590d0a4d457695b22.png