一.搭建服务注册中心
1.首先,创建一个基础的Spring Boot 项目,命名为eureka-server,pom.xml文件添加完对应的依赖后,如下:

 <?xml version="1.0" encoding="UTF-8"?>
<project xmlns="[http://maven.apache.org/POM/4.0.0"](http://maven.apache.org/POM/4.0.0%22); xmlns:xsi="[http://www.w3.org/2001/XMLSchema-instance"](http://www.w3.org/2001/XMLSchema-instance%22);
     xsi:schemaLocation="[http://maven.apache.org/POM/4.0.0](http://maven.apache.org/POM/4.0.0)[http://maven.apache.org/xsd/maven-4.0.0.xsd"](http://maven.apache.org/xsd/maven-4.0.0.xsd%22);>
     <modelVersion>4.0.0</modelVersion>
     <groupId>com.example</groupId>
     <artifactId>eureka-server</artifactId>
     <version>0.0.1-SNAPSHOT</version>
     <packaging>jar</packaging>
     <name>eureka-server</name>
     <description>Demo project for Spring Boot</description>
     <!-- 注意,不同版本的springboot,对应不同的spring cloud版本,这里使用的是1.5.10 -->
     <parent>
           <groupId>org.springframework.boot</groupId>
           <artifactId>spring-boot-starter-parent</artifactId>
           <version>1.5.10.RELEASE</version>
           <relativePath /> <!-- lookup parent from repository -->
     </parent>
     <properties>
          <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
          <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
           <java.version>1.8</java.version>
     </properties>
     <dependencies>
           <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
           </dependency>
           <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <scope>test</scope>
           </dependency>
           <!-- 引入Eureka-server依赖,注册服务中心 -->
           <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-eureka-server</artifactId>
           </dependency>
     </dependencies>
     <dependencyManagement>
           <dependencies>
                <dependency>
                     <groupId>org.springframework.cloud</groupId>
                     <artifactId>spring-cloud-dependencies</artifactId>
                     <version>Edgware.SR1</version>
                     <type>pom</type>
                     <scope>import</scope>
                </dependency>
           </dependencies>
     </dependencyManagement>
     <build>
           <plugins>
                <plugin>
                     <groupId>org.springframework.boot</groupId>
                     <artifactId>spring-boot-maven-plugin</artifactId>
                </plugin>
           </plugins>
     </build>
</project>

2.在EurekaServerApplication,java(名字根据你的项目名字而不同)中加入注解@EnableEurekaServer,使其变为服务注册中心

@EnableEurekaServer
@SpringBootApplication
public class EurekaServerApplication {
     public static void main(String[] args) {
          SpringApplication.run(EurekaServerApplication.class, args);
     }
}

3.(先实现单节点模式的服务注册中心)因为服务注册中心,本身也可以作为服务可被注册到其他的中心,我们如果只是实现单节点的服务注册中心,则需要设置2个配置,设置为本身不能被注册.如下,在配置文件,application.properties

 #端口不冲突即可
server.port=1111
eureka.instance.hostname=localhost
#代表不向注册中心注册自己,所以设置为false
eureka.client.register-with-eureka=false 
# 由于注册中心的职责是维护服务案例,它并不需要去检索服务,所以设置为false
eureka.client.fetch-registry=false
eureka.client.serviceUrl.defaultZone = http://${eureka.instance.hostname}:${server.port}/eureka/

4.启动应用eureka-server ,访问:http://localhost:1111,看到如下图,证明已经成功搭建一个服务注册中心.但里面目前没有服务的提供者,接下来就是往注册中心注册.

image.png

 <?xml version="1.0" encoding="UTF-8"?>
<project xmlns="[http://maven.apache.org/POM/4.0.0"](http://maven.apache.org/POM/4.0.0%22); xmlns:xsi="[http://www.w3.org/2001/XMLSchema-instance"](http://www.w3.org/2001/XMLSchema-instance%22);
     xsi:schemaLocation="[http://maven.apache.org/POM/4.0.0](http://maven.apache.org/POM/4.0.0)[http://maven.apache.org/xsd/maven-4.0.0.xsd"](http://maven.apache.org/xsd/maven-4.0.0.xsd%22);>
     <modelVersion>4.0.0</modelVersion>
     <groupId>com.example</groupId>
     <artifactId>spring_boot</artifactId>
     <version>0.0.1-SNAPSHOT</version>
     <packaging>jar</packaging>
     <name>spring_boot</name>
     <description>Demo project for Spring Boot</description>
     <parent>
           <groupId>org.springframework.boot</groupId>
           <artifactId>spring-boot-starter-parent</artifactId>
           <version>1.5.10.RELEASE</version>
           <relativePath /> <!-- lookup parent from repository -->
     </parent>
     <properties>
          <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
          <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
           <java.version>1.8</java.version>
     </properties>
     <dependencies>
           <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
           </dependency>
           <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <scope>test</scope>
           </dependency>
           <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-eureka</artifactId>
           </dependency>
     </dependencies>
     <dependencyManagement>
           <dependencies>
                <dependency>
                     <groupId>org.springframework.cloud</groupId>
                     <artifactId>spring-cloud-dependencies</artifactId>
                     <version>Edgware.SR1</version>
                     <type>pom</type>
                     <scope>import</scope>
                </dependency>
           </dependencies>
     </dependencyManagement>
     <build>
           <plugins>
                <plugin>
                     <groupId>org.springframework.boot</groupId>
                     <artifactId>spring-boot-maven-plugin</artifactId>
                </plugin>
           </plugins>
     </build>
</project>

2.新建类HelloController,内容如下,注入DiscoveryClient,打印相关的日志内容

@RestController
public class HelloController {
     private final Logger logger = Logger.getLogger(getClass());
     @Autowired
     private DiscoveryClient client;
    
     @RequestMapping(value="/hello",method=RequestMethod.GET)
     public String hello() {
          ServiceInstance localServiceInstance = client.getLocalServiceInstance();
          logger.info("/hello,host:"+localServiceInstance.getHost()+",service_id:"+localServiceInstance.getServiceId());
          return "Spring Boot";
     }
}

3.在application.java,中新增注解,注册为服务客户端@EnableEurekaClient

@EnableEurekaClient
@SpringBootApplication
public class Application {
     public static void main(String[] args) {
          SpringApplication.run(Application.class, args);
     }
}

4.修改application.properties 文件.设置服务名称,以及配置注册到哪个服务注册中心

spring.application.name=hello-service
eureka.client.serviceUrl.defaultZone= http://localhost:1111/eureka/

5.启动应用,此时,刷新:http://localhost:1111, 即可看到如下图,则表示注册成功,这个服务已经在服务注册中心了.

image.png

image.png

 #application-peer1.properties文件内容
spring.application.name=eureka-server
server.port=1111
eureka.instance.hostname=peer1
spring.profiles=peer1
eureka.client.serviceUrl.defaultZone = http://peer2:1112/eureka/
=========================================
#application-peer2.properties文件内容
spring.application.name=eureka-server
server.port=1112
eureka.instance.hostname=peer2
spring.profiles=peer2
eureka.client.serviceUrl.defaultZone = http://peer1:1111/eureka/

2.在etc/hosts 文件中添加peer1,peer2的转换,让上面配置的host形式的serviceUrl能在本地访问,windows的路径:C:/Windows/System32/dirvers/etc/hosts
127.0.0.1 peer1
127.0.0.1 peer2
3.注意,此时eureka-server中的application.properties 文件中,的

#eureka.client.register-with-eureka=false
#eureka.client.fetch-registry=false

这2个配置需要注释掉,因为高可用注册中心,注册中心之间需要能相互注册.所以这2个配置,不能设置为FALSE,可以选择注释掉,或者设置为true
4.运行应用,这里介绍2种方式,第一种是运行jar包,第二种是使用Eclipse启动-配置参数即可,不详细描述.
4.1jar运行的方式:
4.1.1 进入到项目的位置如图

image.png

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spring.application.name=hello-service
eureka.client.serviceUrl.defaultZone= http://peer2:1112/eureka/,http://peer1:1111/eureka/

此时,启动hello-service服务,这个服务就会被同时注册到1111,1112里面,如图显示的是1111的情况.

image.png

以上表示,集群已经搭建好了,并向里面注册了服务提供者
四.服务发现与消费
1.使用Ribbon实现简单的负载均衡,首先,先运行eureka-server集群,再通过命令,运行2个不同端口的hello-service
java -jar .\spring_boot-0.0.1-SNAPSHOT.jar --server.port=8081
java -jar .\spring_boot-0.0.1-SNAPSHOT.jar --server.port=8082

image.png

 <?xml version="1.0" encoding="UTF-8"?>
<project xmlns="[http://maven.apache.org/POM/4.0.0"](http://maven.apache.org/POM/4.0.0%22); xmlns:xsi="[http://www.w3.org/2001/XMLSchema-instance"](http://www.w3.org/2001/XMLSchema-instance%22);
     xsi:schemaLocation="[http://maven.apache.org/POM/4.0.0](http://maven.apache.org/POM/4.0.0)[http://maven.apache.org/xsd/maven-4.0.0.xsd"](http://maven.apache.org/xsd/maven-4.0.0.xsd%22);>
     <modelVersion>4.0.0</modelVersion>
     <groupId>com.example</groupId>
     <artifactId>ribbon-consumer</artifactId>
     <version>0.0.1-SNAPSHOT</version>
     <packaging>jar</packaging>
     <name>ribbon-consumer</name>
     <description>Demo project for Spring Boot</description>
     <!-- 注意,不同版本的springboot,对应不同的spring cloud版本,这里使用的是1.5.10 -->
     <parent>
           <groupId>org.springframework.boot</groupId>
           <artifactId>spring-boot-starter-parent</artifactId>
           <version>1.5.10.RELEASE</version>
           <relativePath/> <!-- lookup parent from repository -->
     </parent>
     <properties>
          <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
          <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
           <java.version>1.8</java.version>
     </properties>
     <dependencies>
           <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
           </dependency>
           <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <scope>test</scope>
           </dependency>
           <!--  -->
           <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-eureka</artifactId>
           </dependency>
           <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-ribbon</artifactId>
           </dependency>
     </dependencies>
<dependencyManagement>
           <dependencies>
                <dependency>
                     <groupId>org.springframework.cloud</groupId>
                     <artifactId>spring-cloud-dependencies</artifactId>
                     <version>Edgware.SR1</version>
                     <type>pom</type>
                     <scope>import</scope>
                </dependency>
           </dependencies>
     </dependencyManagement>
     <build>
           <plugins>
                <plugin>
                     <groupId>org.springframework.boot</groupId>
                     <artifactId>spring-boot-maven-plugin</artifactId>
                </plugin>
           </plugins>
     </build>
</project>

3.在RibbonConsumerApplication.java中,注册为client端,创建RestTemplate的SpringBean实例

@EnableEurekaClient
@SpringBootApplication
public class RibbonConsumerApplication {
     
     @Bean
     @LoadBalanced
     RestTemplate restTemplate() {
          return new RestTemplate();
     }
     public static void main(String[] args) {
          SpringApplication.run(RibbonConsumerApplication.class, args);
     }
}

4.创建ConsumerController.java,代码如下:

 @RestController
public class ConsumerController {
     @Autowired
     RestTemplate restTemplate;

     @RequestMapping(value="/ribbon-consumer",method=RequestMethod.GET)
     public String ribbon() {
            //url-地址名字,是对应上文的hello-service,不能使用ip,这就没有负载均衡的意义
          return   restTemplate.getForEntity("http://HELLO-SERVICE/hello", String.class).getBody();
     }
}

5.在application.properties 文件中,配置相关信息

spring.application.name=ribbon-consumer
server.port=9000
eureka.client.serviceUrl.defaultZone= http://localhost:1111/eureka/

6.启动ribbon-consumer 应用,会发现服务就会注册到服务注册中心了.

image.png