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最近规划自动化运维以及统一监控需求，鉴于目前公司内部大部分项目采用spring cloud体系架构、另外还有一些老的传统spring web的项目，于是就考虑把老的项目通过低成本改造的方式接入spring cloud体系，也就是可以通过eureka注册和服务发现、通过zuul服务路由。

说干就干，通过eureka官方实例和研究spring boot注册eureka源码发现这个也很容易实现，所以废话不多说，直接贴代码了 。

首先加入项目依赖（maven为例）

<dependency><groupId>com.netflix.eureka</groupId><artifactId>eureka-client</artifactId><version>1.4.12</version><exclusions><exclusion><groupId>javax.servlet</groupId><artifactId>servlet-api</artifactId></exclusion><exclusion><groupId>com.google.guava</groupId><artifactId>guava</artifactId></exclusion><exclusion><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-annotations</artifactId></exclusion><exclusion><groupId>javax.ws.rs</groupId><artifactId>jsr311-api</artifactId></exclusion></exclusions>
</dependency><dependency><groupId>com.netflix.archaius</groupId><artifactId>archaius-core</artifactId><version>0.7.4</version><exclusions><exclusion><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-annotations</artifactId></exclusion></exclusions></dependency><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-netflix-core</artifactId><version>1.2.6.RELEASE</version><exclusions><exclusion><groupId>org.springframework.boot</groupId><artifactId>spring-boot-autoconfigure</artifactId></exclusion></exclusions></dependency>

加入配置文件

eureka.region=default
eureka.registration.enabled=true
eureka.preferSameZone=true
eureka.shouldUseDns=false
eureka.serviceUrl.default=http://192.168.1.100:7861/eureka
eureka.decoderName=JacksonJsoneureka.name=demo
eureka.vipAddress=${eureka.name}-service
eureka.port=8081
eureka.homePageUrl=http://192.168.1.101:${eureka.port}
eureka.healthCheckUrl=http://192.168.1.101:${eureka.port}/service/health
eureka.statusPageUrl=http://192.168.1.101:${eureka.port}/service/info

• spring.cloud.client.ipAddress :为自定义变量
• healthCheckUrl，statusPageUrl接口可以不要，但是为了监控可以自己实现一个简单的接口即可

初始化eureka客户端

private void initEurekaClient() throws Exception{Properties properties = new Properties();InputStream inputStream = Thread.currentThread().getContextClassLoader().getResourceAsStream("eureka.properties");properties.load(inputStream);//properties.setProperty("eureka.ipAddr", IpUtils.getLocalIpAddr());instanceId = properties.getProperty("eureka.ipAddr") + ":" + properties.getProperty("eureka.ipAddr") + "/" + properties.getProperty("eureka.name");properties.setProperty("eureka.instanceId", instanceId);ConfigurationManager.loadProperties(properties);MyDataCenterInstanceConfig instanceConfig = new MyDataCenterInstanceConfig();InstanceInfo instanceInfo = new EurekaConfigBasedInstanceInfoProvider(instanceConfig).get();applicationInfoManager = new ApplicationInfoManager(instanceConfig, instanceInfo);DefaultEurekaClientConfig clientConfig = new DefaultEurekaClientConfig();eurekaClient = new DiscoveryClient(applicationInfoManager, clientConfig);}

注册服务

private void waitForRegistrationWithEureka() {applicationInfoManager.setInstanceStatus(InstanceInfo.InstanceStatus.STARTING);try {Thread.sleep(2000);} catch (InterruptedException e) {}applicationInfoManager.setInstanceStatus(InstanceInfo.InstanceStatus.UP);long startTime = System.currentTimeMillis();//开启一个线程验证注册结果new Thread(new Runnable() {@Overridepublic void run() {while (true) {if (System.currentTimeMillis() - startTime > VERIFY_WAIT_MILLIS) {log.warn(" >>>> service registration status not verify,please check it!!!!");return;}try {List<InstanceInfo> serverInfos = eurekaClient.getInstancesByVipAddress(vipAddress, false);for (InstanceInfo nextServerInfo : serverInfos) {if (nextServerInfo.getIPAddr().equals(IpUtils.LOCAL_BACK_IP)|| nextServerInfo.getIPAddr().equals(IpUtils.getLocalIpAddr())) {String instanceInfoJson = JsonUtils.getMapper().writerWithDefaultPrettyPrinter().writeValueAsString(nextServerInfo);log.info("verifying service registration with eureka finished,instance:\n{}",instanceInfoJson);return;}}} catch (Throwable e) {}try {Thread.sleep(5000);} catch (Exception e1) {}log.info("Waiting 5s... verifying service registration with eureka ...");}}}).start();}

通过这几步就完成了eureka的注册，登录eureka控制台你将能看到对应注册信息。但是在zuul转发调用过程发现一个问题：无法识别hostname，如果你们的服务器之间没有做hostname同步就需要继续改造，于是就看了下springboot注册eureka有一个配置项eureka.instance.preferIpAddress，所以我们也可以模仿他的实现。于是在初始化客户端的时候我们需要这样改造：

MyDataCenterInstanceConfig instanceConfig = new MyDataCenterInstanceConfig(){@Overridepublic String getHostName(boolean refresh) {String hostName = super.getHostName(refresh);if(ResourceUtils.getBoolean("eureka.preferIpAddress")){hostName = IpUtils.getLocalIpAddr();}return hostName;}@Overridepublic String getIpAddress() {return IpUtils.getLocalIpAddr();}};

这样，注册的真实服务地址就是ip了。服务注册就搞定收工了。

接下来就是服务发现，及与其他springboot项目一样通过注册中心vipAddress互相调用。实际过程就是调用前去eureka拿一个真实地址替换vipAddress变量。

获取真实服务地址

public String getRealServerHost(String serviceId){InstanceInfo serverInfo = eurekaClient.getNextServerFromEureka(serviceId, false);String realServerName = serverInfo.getIPAddr() + ":" + serverInfo.getPort();return realServerName;
}

下面是我实现的几个resttemplate

public class EurekaRestTemplateBuilder {private static Map<String, RestTemplate> restTemplates = new HashMap<>();public static synchronized RestTemplate build(ClientHttpRequestInterceptor ...interceptors ){return build("default", interceptors);}public static synchronized RestTemplate build(String name,ClientHttpRequestInterceptor ...interceptors ){if(restTemplates.containsKey(name))return restTemplates.get(name);SimpleClientHttpRequestFactory factory = new EurekaClientHttpRequestFactory();  factory.setReadTimeout(15000);//ms  factory.setConnectTimeout(5000);//ms RestTemplate restTemplate = new RestTemplate(factory);List<ClientHttpRequestInterceptor> interceptorList = new ArrayList<>();interceptorList.add(new RestTemplateAutoHeaderInterceptor());if(interceptors != null && interceptors.length > 0){for (ClientHttpRequestInterceptor interceptor : interceptors) {interceptorList.add(interceptor);}}restTemplate.setInterceptors(interceptorList);//restTemplate.setErrorHandler(new CustomResponseErrorHandler());//restTemplates.put(name, restTemplate);return restTemplate;}private static class EurekaClientHttpRequestFactory extends SimpleClientHttpRequestFactory{@Overridepublic ClientHttpRequest createRequest(URI uri, HttpMethod httpMethod) throws IOException {uri = convertToRealUri(uri);return super.createRequest(uri, httpMethod);}@Overridepublic AsyncClientHttpRequest createAsyncRequest(URI uri, HttpMethod httpMethod) throws IOException {uri = convertToRealUri(uri);return super.createAsyncRequest(uri, httpMethod);}private URI convertToRealUri(URI uri){String serviceId = uri.getHost();try {              String realHost = EurekaRegistry.getInstance().getRealServerHost(serviceId);uri = new URI(uri.toString().replace(serviceId, realHost));return uri;} catch (Exception e) {throw new RuntimeException(e);}}}
}

接下来就可以调用其他eureka注册服务了。

private RestTemplate restTemplate = EurekaRestTemplateBuilder.build();public List<IdNamePair> getProvinces() {ParameterizedTypeReference<List<IdNamePair>> arearesponseType = new ParameterizedTypeReference<List<IdNamePair>>() {};List<IdNamePair> lists = restTemplate.exchange("http://DEMO-SERVICE/region/provinces", HttpMethod.GET, null, arearesponseType).getBody();return lists;}

ZUUL转发配置

zuul.routes.demo.path=/demo/**
zuul.routes.demo.serviceId=demo-service

到此，服务注册和服务发现都完成了。

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