在搭建Spring Cloud Eureka环境前先要了解整个架构的组成，常用的基础模式如下图：

服务提供者：将springboot服务编写好以后，通过配置注册中心地址方式注册，提供给消费者使用。
注册中心：服务的中间桥梁，服务提供者将服务注册。服务消费者可以通过注册信息调用需要使用的服务。
服务消费者：通过规定的调用方式，读取注册中心的注册信息，调用相应的服务。

根据后续的服务复杂度进化以后，可以看到服务提供者也可以是服务消费者，服务消费者也可以是服务提供者。根据不同的业务情况是可以互相调用的。

下面来搭建一个基础的eureka。环境还是使用的之前的spring官方下载的。

内容写的比较详细，可以跟这一步步操作。

一、注册中心

以下是几个需要修改和添加的地方，后面会有完整的pom.xml

<parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.1.3.RELEASE</version><relativePath /> </parent><dependencyManagement><dependencies><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-dependencies</artifactId><version>Finchley.SR2</version><type>pom</type><scope>import</scope></dependency></dependencies></dependencyManagement><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-netflix-eureka-server</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-actuator</artifactId></dependency>

这里采用Finchley.SR2版本 springboot版本改成 2.1.3.RELEASE

完整的pom.xml

<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 https://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.1.3.RELEASE</version><relativePath /> </parent><groupId>com.example</groupId><artifactId>eureka1</artifactId><version>0.0.1-SNAPSHOT</version><name>eureka1</name><description>Demo project for Spring Boot</description><properties><java.version>1.8</java.version></properties><dependencyManagement><dependencies><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-dependencies</artifactId><version>Finchley.SR2</version><type>pom</type><scope>import</scope></dependency></dependencies></dependencyManagement><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter</artifactId></dependency><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-netflix-eureka-server</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-actuator</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope><exclusions><exclusion><groupId>org.junit.vintage</groupId><artifactId>junit-vintage-engine</artifactId></exclusion></exclusions></dependency></dependencies><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build></project>

package com.example.demo;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;@EnableEurekaServer@SpringBootApplicationpublic class Eureka1Application {public static void main(String[] args) {SpringApplication.run(Eureka1Application.class, args);}}

然后在代码文件中添加@EnableEurekaServer注解

修改application.yml文件

server:  port: 3000 # 端口eureka:  instance:    hostname: eureka-center     appname: 注册中心  client:    registerWithEureka: false # 单点的时候设置为 false 禁止注册自身    fetchRegistry: false    serviceUrl:      defaultZone: http://localhost:3000/eureka  server:    enableSelfPreservation: false    evictionIntervalTimerInMs: 4000

启动服务

浏览器输入 http://127.0.0.1:3000

证明注册中心搭建成功了

二、服务提供者

前面的步骤一样

ProviderController是新建的一个服务代码

<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-netflix-eureka-client</artifactId></dependency>

不同的地方有加了一个spring-boot-starter-web和spring-cloud-starter-netflix-eureka-client客户端
完整的pom.xml

<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 https://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.1.3.RELEASE</version><relativePath /> </parent><groupId>com.example</groupId><artifactId>eurekaClient1</artifactId><version>0.0.1-SNAPSHOT</version><name>eurekaClient1</name><description>Demo project for Spring Boot</description><properties><java.version>1.8</java.version></properties><dependencyManagement><dependencies><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-dependencies</artifactId><version>Finchley.SR2</version><type>pom</type><scope>import</scope></dependency></dependencies></dependencyManagement><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-netflix-eureka-client</artifactId></dependency></dependencies><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build></project>

EurekaClient1Application

package com.example.demo;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.cloud.netflix.eureka.EnableEurekaClient;@EnableEurekaClient@SpringBootApplicationpublic class EurekaClient1Application {public static void main(String[] args) {SpringApplication.run(EurekaClient1Application.class, args);}}

ProviderController

package com.example.demo;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;@RestControllerpublic class ProviderController {    @RequestMapping(value = "/hello")    public String hello(){  return "hello spring cloud!";    }    @RequestMapping(value = "/nice")    public String nice(){  return "nice to meet you!";    }}

application.yml

server:  port: 3001eureka:  instance:    preferIpAddress: true  client:    serviceUrl:      defaultZone: http://localhost:3000/eureka  ## 注册到 eureka spring:  application:    name: single-provider  ## 应用程序名称，后面会在消费者中用到

http://127.0.0.1:3001/hello

http://127.0.0.1:3000/

证明服务已经注册成功

三、服务消费者

前面还是同上

<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-openfeign</artifactId></dependency><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-netflix-eureka-client</artifactId></dependency>

pom.xml新增以上内容

完整pom.xml

<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 https://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.1.3.RELEASE</version><relativePath /> </parent><groupId>com.example</groupId><artifactId>eurekaClient1</artifactId><version>0.0.1-SNAPSHOT</version><name>eurekaClient1</name><description>Demo project for Spring Boot</description><properties><java.version>1.8</java.version></properties><dependencyManagement><dependencies><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-dependencies</artifactId><version>Finchley.SR2</version><type>pom</type><scope>import</scope></dependency></dependencies></dependencyManagement><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-openfeign</artifactId></dependency><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-netflix-eureka-client</artifactId></dependency></dependencies><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build></project>

EurekaClient2Application

package com.example.demo;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.cloud.client.loadbalancer.LoadBalanced;import org.springframework.cloud.netflix.eureka.EnableEurekaClient;import org.springframework.cloud.openfeign.EnableFeignClients;import org.springframework.context.annotation.Bean;import org.springframework.web.client.RestTemplate;@EnableEurekaClient@EnableFeignClients@SpringBootApplicationpublic class EurekaClient2Application {/**     * 注入 RestTemplate      * 并用 @LoadBalanced 注解，用负载均衡策略请求服务提供者     * 这是 Spring Ribbon 的提供的能力     * @return     */    @LoadBalanced    @Bean    public RestTemplate restTemplate() { return new RestTemplate(); //用于调用服务对象    }public static void main(String[] args) {SpringApplication.run(EurekaClient2Application.class, args);}}

ConsumerController

package com.example.demo;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;import org.springframework.web.client.RestTemplate;@RestControllerpublic class ConsumerController {@Autowired    private RestTemplate restTemplate;    private static final String applicationName = "single-provider";//服务注册名    @RequestMapping(value = "commonRequest")    public Object commonRequest(){ String url = "http://"+ applicationName +"/hello"; String s = restTemplate.getForObject(url,String.class);//Ribbon方式调用服务 return s;    }}

application.yml

server:  port: 3002eureka:  client:    serviceUrl:      defaultZone: http://127.0.0.1:3000/eureka  ## 注册到 eureka  instance:    preferIpAddress: truespring:  application:    name: single-customer

启动服务
http://127.0.0.1:3002/commonRequest

返回服务提供者的 hello方法参数。

整个最简单的过程就完成了，需要更好的使用spring cloud 后续需要了解分布式、负载均衡、熔断等概念。在后续章节将一步步的拆分。