1.什么是注冊中心

注冊中心主要有三種角色：

• 服務提供者（RPC Server）：在啟動時，向 Registry 注冊自身服務，并向 Registry 定期發送心跳匯報存活狀態。

• 服務消費者（RPC Client）：在啟動時，向 Registry 訂閱服務，把 Registry 返回的服務節點列表緩存在本地內存中，并與 RPC Sever 建立連接。

• 服務注冊中心（Registry）：用于保存 RPC Server 的注冊信息，當 RPC Server 節點發生變更時，Registry 會同步變更，RPC Client 感知后會刷新本地 內存中緩存的服務節點列表。

2.框架版本

spring boot：2.7.13

spring cloud：2021.0.1

3.xxx-discovery-etcd

支持etcd作為服務的注冊中心，在微服務中使用

3.1.使用

pom.xml中引入依賴

<dependency><groupId>x.xx.xxx</groupId><artifactId>xxx-discovery-etcd</artifactId>
</dependency>

application.yml中配置

spring:application:name: etcd-provider-examplexxx:discovery:etcd:server-addr: http://192.168.184.133:2379instance-name: provider1 ? ? ? ? ? ? ? ?

啟動主類增加注解@EnableDiscoveryClient

4.Spring Cloud和xxx-etcd-discovery的結合

4.1.etcd-provider-demo

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion>
?<groupId>org.example</groupId><artifactId>etcd-provider-demo</artifactId><version>1.0-SNAPSHOT</version>
?<dependencies><dependency><groupId>x.xx.xxx</groupId><artifactId>xxx-discovery-etcd</artifactId></dependency>
?<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency>
?<dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-bootstrap</artifactId></dependency>
?</dependencies>
?
</project>

bootstrap.yml

server:port: 18082
spring:application:name: etcd-provider-example
?
xxx:discovery:etcd:server-addr: http://192.168.184.133:2379instance-name: provider1
?
logging:level:root: DEBUGio:grpc:netty:NettyClientHandler: INFO
?org:springframework:boot:autoconfigure: INFO

EtcdProviderExampleApplication

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
?
@SpringBootApplication
@EnableDiscoveryClient
public class EtcdProviderExampleApplication {
?public static void main(String[] args) {SpringApplication.run(EtcdProviderExampleApplication.class, args);}
}

EchoController

package x.xx.xxx.etcd.demo;
?
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
?
@RestController
public class EchoController {@RequestMapping(value = "/echo/{string}", method = RequestMethod.GET)public String echo(@PathVariable String string) {return System.currentTimeMillis() + "--Hello Etcd Discovery " + string;}
}

4.2.etcd-consumer-demo

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion>
?<groupId>org.example</groupId><artifactId>etcd-consumer-demo</artifactId><version>1.0-SNAPSHOT</version>
?<dependencies><dependency><groupId>x.xx.xxx</groupId><artifactId>xxx-discovery-etcd</artifactId></dependency>
?<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency>
?<dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-bootstrap</artifactId></dependency>
?<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-webflux</artifactId></dependency>
?</dependencies>
?
</project>

bootstrap.yml

server:port: 18081
?
spring:application:name: etcd-consumer-example
?
xxx:discovery:etcd:server-addr: http://192.168.184.133:2379instance-name: consumer1logging:level:root: DEBUGio:grpc:netty:NettyClientHandler: INFO
?org:springframework:boot:autoconfigure: INFO

EtcdConsumerExampleApplication

package x.xx.xxx.etcd.demo;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;
import org.springframework.web.reactive.function.client.WebClient;@SpringBootApplication
@EnableDiscoveryClient
public class EtcdConsumerExampleApplication {public static void main(String[] args) {SpringApplication.run(EtcdConsumerExampleApplication.class, args);}@LoadBalanced@Beanpublic RestTemplate restTemplate() {return new RestTemplate();}@Bean@LoadBalancedpublic WebClient.Builder loadBalancedWebClientBuilder() {return WebClient.builder();}
}

TestController

package x.xx.xxx.etcd.demo;import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;
import org.springframework.web.reactive.function.client.WebClient;@RestController
public class TestController {private final RestTemplate restTemplate;@Autowiredpublic TestController(RestTemplate restTemplate) {this.restTemplate = restTemplate;}@RequestMapping(value = "/echo/{str}", method = RequestMethod.GET)public String echo(@PathVariable String str) {return restTemplate.getForObject("http://etcd-provider-example/echo/" + str, String.class);}@Autowiredprivate WebClient.Builder webClientBuilder;@RequestMapping(value = "/echo/webClient/{str}", method = RequestMethod.GET)public String echoWebClient(@PathVariable String str) {WebClient webClient = webClientBuilder.build();webClient.get().uri("http://etcd-provider-example/echo/" + str).retrieve().bodyToMono(String.class).subscribe(response -> {System.err.println("控制臺響應結果:" + response);});return System.currentTimeMillis() + "--echoWebClient--" + str + "--請查看控制臺是否執行成功!";}}

4.3.啟動主程序

EtcdProviderExampleApplication

EtcdConsumerExampleApplication

通過ETCD Manager查看，如下表示注冊成功

請求etcd-consumer-demo中接口，查看服務發現功能，更改測試接口，可查看TestController

http://localhost:18081/echo/6666

瀏覽器返回如下信息表示服務發現成功

1705978409084--Hello Etcd Discovery 6666

5.xxx-etcd-discovery詳解

5.1.可配置屬性

5.2.存儲到etcd的格式

5.3.監控ectd服務端事件,并發送事件

5.4.啟動全量查所有服務列表并緩存