最近接手一个项目，各子工程之间通过feign调用；各服务部署在K8S上，通过nacos管理配置；由于服务部署的机器无法开放端口等原因，导致本机服务与测试环境网络端口无法互通，故需要重写feign的调用地址；个人总结的方法有以下几种：
目录
第一种：feignclient配置URL
第二种：实现RequestInterceptor接口；
第三种：重写feign的client的execute方法；
第一种：feignclient配置URL
在feignclient里写一个固定地址或者写一个可配置的地址，这样可以在配置文件里指定,这种方式在创建feign客户端的时候就需要规划好。
1.1 固定地址
@FeignClient(name = "feignCustomerService", url = "http://localhost:8080")
public interface FeignCustomerService {/*** 请求客户的接口*/@RequestMapping(value = "order/update", method = RequestMethod.POST)@Headers(value = "Content-Type: application/json")OrderHttpResponse updateOrder(@RequestBody OrderUpdateDTO orderUpdateDTO);}1.2 可配置的地址
@FeignClient(name = "feignCustomerService", url = "${customer.url}")
public interface FeignCustomerService {@RequestMapping(value = "test/list", method = RequestMethod.POST)@Headers(value = "Content-Type: application/json")OrderHttpResponse updateTest(@RequestBody OrderUpdateDTO orderUpdateDTO);}配置文件配置地址
customer.url=http://localhost:8080第二种：实现RequestInterceptor接口；
这种方式具有局限性，在nacos上注册的服务IP与本机IP不一致的时候（连接VPN）可能依旧调不通服务，但是实现RequestInterceptor接口可以处理全局请求（header，身份认证等）
@Component
public class Oauth2TokenRequestInterceptor implements RequestInterceptor {@Overridepublic void apply(RequestTemplate requestTemplate) {// 获取请求中的消息头ServletRequestAttributes attributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();HttpServletRequest request = attributes.getRequest();String requestHeader = request.getHeader(HttpHeaders.AUTHORIZATION);if (StringUtils.isNotBlank(requestHeader) && requestHeader.startsWith("Bearer ")) {// 将消息头塞入到请求模板中requestTemplate.header(HttpHeaders.AUTHORIZATION, requestHeader);}//重写URL，访问指定服务String url = target.url();String newUrl = "http://localhost:8080";template.target(newUrl );}
}
第三种：重写feign的client的execute方法；
这种方式可以自定义负载均衡的策略，也可以自定义访问指定服务IP，这里以FeignBlockingLoadBalancerClient为例
配置类
package com.***.redirect;import lombok.Getter;
import lombok.Setter;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.cloud.context.config.annotation.RefreshScope;
import org.springframework.stereotype.Component;import java.util.Map;@Getter
@Setter
@RefreshScope
@ConfigurationProperties("localbalance")
@Component
public class LocalFeignPerpreties {private Boolean enable;private Map<String,String> rule;
}
配置文件配置内容：
localbalance:enable: truerule:aiflow-sys: http://IP:8888/SERVICEaiflow-auth: http://IP:8888/SERVICE重写FeignBlockingLoadBalancerClient 的execute方法
package com.***.redirect;import feign.Client;
import feign.Request;
import feign.RequestTemplate;
import feign.Response;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang3.StringUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.discovery.DiscoveryClient;
import org.springframework.cloud.loadbalancer.blocking.client.BlockingLoadBalancerClient;
import org.springframework.cloud.netflix.ribbon.SpringClientFactory;
import org.springframework.cloud.openfeign.loadbalancer.FeignBlockingLoadBalancerClient;
import org.springframework.cloud.openfeign.ribbon.CachingSpringLoadBalancerFactory;
import org.springframework.cloud.openfeign.ribbon.LoadBalancerFeignClient;
import org.springframework.context.annotation.Primary;
import org.springframework.util.Assert;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;
import org.springframework.web.util.UriComponentsBuilder;import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
import java.net.URI;
import java.net.URLEncoder;
import java.nio.charset.Charset;
import java.util.*;//@ConditionalOnBean
//@Primary
@Slf4j
public class LocalBlockingLoadBalancerClient extends FeignBlockingLoadBalancerClient {private Client delegate;private BlockingLoadBalancerClient loadBalancerClient;@Autowiredprivate LocalFeignPerpreties localFeignPerpreties;public LocalBlockingLoadBalancerClient(Client delegate,BlockingLoadBalancerClient loadBalancerClient) {super(delegate, loadBalancerClient);this.delegate = delegate;this.loadBalancerClient = loadBalancerClient;}@Overridepublic Response execute(Request request, Request.Options options) throws IOException {try {log.info("feign -> 配置化客户端");Boolean enable = localFeignPerpreties.getEnable();if (enable) {String url = request.url();RequestTemplate requestTemplate = request.requestTemplate();String name = requestTemplate.feignTarget().name();Map<String, String> urlMap = localFeignPerpreties.getRule();if (urlMap != null && urlMap.containsKey(name)) {URI uri = URI.create(url);StringBuffer strbuf = new StringBuffer();strbuf.append(urlMap.get(name)).append(uri.getPath());if (StringUtils.isNotBlank(uri.getQuery())) {strbuf.append("?").append(uri.getQuery());}requestTemplate.target(urlMap.get(name));Map<String, Collection<String>> headers = request.headers();Map<String, Collection<String>> newheaders = new HashMap<>();//处理请求头ServletRequestAttributes attributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();HttpServletRequest attributesRequest = attributes.getRequest();Enumeration<String> headerNames = attributesRequest.getHeaderNames();if (headerNames != null) {while (headerNames.hasMoreElements()) {String element = headerNames.nextElement();String elementVal = attributesRequest.getHeader(element);newheaders.put(element, new ArrayList<String>() {{add(elementVal);}});}}//构建新的requestRequest newRequest = buildRequest(request, strbuf.toString(), newheaders);return super.getDelegate().execute(newRequest, options);}}} catch (Exception e) {e.printStackTrace();}log.info("feign -> 默认客户端");return super.execute(request, options);}protected Request buildRequest(Request request,String reconstructedUrl,Map<String, Collection<String>> headers) {return Request.create(request.httpMethod(), reconstructedUrl, headers,request.body(), Charset.forName("UTF-8"), request.requestTemplate());}}
使配置类和重写的client生效
package com.***.redirect;import feign.Client;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.cloud.loadbalancer.blocking.client.BlockingLoadBalancerClient;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;//@ConditionalOnProperty(prefix = ReBalancerProperties.prefix,name = "enable",havingValue = "true")
@Configuration
@EnableConfigurationProperties(value = {LocalFeignPerpreties.class})
public class ReBalancerConfiguration {@Beanpublic Client feignReBalancer(BlockingLoadBalancerClient discoveryClient) {return new LocalBlockingLoadBalancerClient(new Client.Default(null, null),discoveryClient);}
}
到这里基本上可以满足重写feign URL的需求了，这个前提条件是代码在application启动类的下一级，如果不在启动类的同级或者下一级，是无法扫描到相关类的，这时我们可以注解完成扫描，需要在启动类上加上相关注解
package com.***.annotation;import com.***.ReBalancerConfiguration;
import org.springframework.boot.autoconfigure.AutoConfigurationPackage;
import org.springframework.context.annotation.Import;import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Import(ReBalancerConfiguration.class)
@AutoConfigurationPackage
public @interface EnableLocalFeignClient {
}
)
