Spring Cloud 入门教程1、服务注册与发现（Eureka）

一、前言

1、什么是Eureka？

Eureka是Netflix开源的服务注册与发现框架，Eureka由两个组件组成：Eureka服务器和Eureka客户端。

Eureka Server提供服务注册服务，各个节点启动后，会在Eureka Server中进行注册，这样EurekaServer中的服务注册表中将会存储所有可用服务节点的信息，服务节点的信息可以在界面中直观的看到。

Eureka客户端是一个Java客户端，用来简化与服务器的交互、作为轮询负载均衡器，并提供服务的故障切换支持。

2、Eureka概览

3、本篇环境信息

二、搭建Eureka Server

1、创建Eureka Server项目

• 创建一个Spring Boot工程

使用maven-archtype-quickstart模板创建项目

• 在pom.xml加入相关依赖

<?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>io.ken.springcloud.eurekaserver</groupId>
<artifactId>eurekaserver</artifactId>
<version>1.0-SNAPSHOT</version>
<name>eurekaserver</name>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
</properties>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.0.RELEASE</version>
</parent>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Finchley.BUILD-SNAPSHOT</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
<scope>test</scope>
</dependency>
</dependencies>
<repositories>
<repository>
<id>spring-snapshots</id>
<name>Spring Snapshots</name>
<url>https://repo.spring.io/libs-snapshot</url>
<snapshots>
<enabled>true</enabled>
</snapshots>
</repository>
</repositories>
<build>
<finalName>eurekaserver</finalName>
</build>
</project>

2、配置EurekaServer启动类

修改srcmainjavaiokenspringcloudeurekaserverApp.java
基于Spring Boot创建启动类，添加上 @EnableEurekaServer 注解

package io.ken.springcloud.eurekaserver;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;
@EnableEurekaServer
@SpringBootApplication
public class App {
public static void main(String[] args) {
SpringApplication.run(App.class, args);
}
}

3、配置Eureka Server

在srcmain下创建文件夹resources文件夹并设置为Resources Root

在resources文件夹下创建application.yml文件并配置Eureka Server

server:
port: 8800
spring:
application:
name: EurekaServer
eureka:
client:
registerWithEureka: false
fetchRegistry: false
serviceUrl:
defaultZone: http://localhost:${server.port}/eureka/

Eureka默认会以客户端来注册自己，所以registerWithEureka、fetchRegistry要配置为false。

4、Eureka Server信息预览

启动Eureka Server项目后，访问：http://localhost:8800/ ，可以看到下面的页面，其中还没有发现任何服务。

三、搭建服务并注册（Eureka Client）

1、创建Eureka Client项目

• 创建一个Spring Boot工程

使用maven-archtype-quickstart模板创建项目

• 在pom.xml加入相关依赖

<?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>io.ken.springcloud.helloservice</groupId>
<artifactId>helloservice</artifactId>
<version>1.0-SNAPSHOT</version>
<name>helloservice</name>
<url>http://ken.io</url>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
</properties>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.0.RELEASE</version>
</parent>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Finchley.BUILD-SNAPSHOT</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<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>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
<scope>test</scope>
</dependency>
</dependencies>
<repositories>
<repository>
<id>spring-snapshots</id>
<name>Spring Snapshots</name>
<url>https://repo.spring.io/libs-snapshot</url>
<snapshots>
<enabled>true</enabled>
</snapshots>
</repository>
</repositories>
<build>
<finalName>helloservice</finalName>
</build>
</project>

2、配置Eureka Client启动类

修改srcmainjavaiokenspringcloudhelloserviceApp.java
基于Spring Boot创建启动类，添加上 @EnableDiscoveryClient 注解

package io.ken.springcloud.helloservice;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
@EnableDiscoveryClient
@SpringBootApplication
public class App {
public static void main(String[] args) {
SpringApplication.run(App.class, args);
}
}

3、创建测试服务

在srcmainjavaiokenspringcloudhelloservice创建package：controller
然后创建HelloController.java

package io.ken.springcloud.helloservice.controller;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.discovery.DiscoveryClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class HelloController {
@Autowired
DiscoveryClient discoveryClient;
@RequestMapping("/")
public Object index() {
return "hello service";
}
@RequestMapping("/info")
public Object info() {
return discoveryClient.getServices();
}
}

4、配置Eureka Client

在srcmain下创建文件夹resources文件夹并设置为Resources Root

在resources文件夹下创建application.yml文件并配置Eureka Client

server:
port: 8601
spring:
application:
name: helloservice
eureka:
client:
serviceUrl:
defaultZone: http://localhost:8800/eureka/

5、服务注册&访问测试

HelloService项目成功启动后，访问 http://localhost:8601 ,或者 http://localhost:8601/info
查看是否正常启动

访问 http://localhost:8800 ，会发现服务已注册

搞定！

四、备注

• 本篇示例代码

https://github.com/ken-io/springcloud-course/tree/master/chapter-01