SpringCloud Eureka微服务的注册和发现
本文将介绍Eureka的原理和作用:
Eureka Server:提供服务注册和发现的功能(Eureka Server)
Eureka Client:提供服务(Service Provider)
Eureka Client:消费服务(Service Consumer)
二、创建服务注册中心(Eureka Server)
工程结构图
2.1 首先创建一个maven主工程。
首先创建一个主Maven工程,在其pom文件引入依赖,spring Boot版本为2.0.3.RELEASE,Spring Cloud版本为Finchley.RELEASE。这个pom文件作为父pom文件,起到依赖版本控制的作用,其他module工程继承该pom。
主要pom.xml的代码如下:
<?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>com.forezp</groupId>
<artifactId>sc-f-chapter1</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>pom</packaging>
<name>sc-f-chapter1</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.3.RELEASE</version>
<relativePath/>
</parent>
<modules>
<module>eureka-server</module>
<module>eureka-client</module>
</modules>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
<spring-cloud.version>Finchley.RELEASE</spring-cloud.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring-cloud.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
2.1 然后创建2个model工程:
一个model工程作为服务注册中心,即Eureka Server
下面以创建server为例子,详细说明创建过程:
右键工程->创建model-> 选择spring initialir 如下图:
下一步->选择cloud discovery->eureka server ,然后一直下一步就行了。
创建完后的工程
Eureka Server 的pom.xml继承了父pom文件,并引入spring-cloud-starter-netflix-eureka-server的依赖,代码如下:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.forezp</groupId>
<artifactId>eureka-server</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>eureka-server</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>com.forezp</groupId>
<artifactId>Eureka</artifactId>
<version>0.0.1-SNAPSHOT</version>
<relativePath/>
</parent>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
</dependency>
</dependencies>
</project>
2.3 启动一个服务注册中心,
只需要一个注解@EnableEurekaServer,这个注解需要在springboot工程的启动application类上加:
@SpringBootApplication
@EnableEurekaServer
public class EurekaServerApplication {
public static void main(String[] args) {
SpringApplication.run( EurekaServerApplication.class, args );
}
}
eureka是一个高可用的组件,它没有后端缓存,每一个实例注册之后需要向注册中心发送心跳(因此可以在内存中完成),在默认情况下erureka server也是一个eureka client ,必须要指定一个 server。eureka server的配置文件appication.yml:
server: port: 8761 eureka: instance: hostname: localhost client: registerWithEureka: false fetchRegistry: false serviceUrl: defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/ spring: application: name: eurka-server
通过eureka.client.registerWithEureka:false和fetchRegistry:false来表明自己是一个eureka server.
三、创建一个服务提供者 (eureka client)
pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.forezp</groupId>
<artifactId>eureka-client</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>eureka-client</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>com.forezp</groupId>
<artifactId>Eureka</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
通过注解@EnableEurekaClient 表明自己是一个eurekaclient.
@SpringBootApplication
@EnableEurekaClient
public class ServiceHiApplication {
public static void main(String[] args) {
SpringApplication.run( ServiceHiApplication.class, args );
}
@Value("${server.port}")
String port;
@RequestMapping("/hi")
public String home(@RequestParam(value = "name", defaultValue = "forezp") String name) {
return "hi " + name + " ,i am from port:" + port;
}
}
仅仅@EnableEurekaClient是不够的,还需要在配置文件中注明自己的服务注册中心的地址,application.yml配置文件如下:
server: port: 8762 spring: application: name: service-hi eureka: client: serviceUrl: defaultZone: http://localhost:8761/eureka/
需要指明spring.application.name,这个很重要,这在以后的服务与服务之间相互调用一般都是根据这个name
eureka client