一、采用Eureka作为服务注册与发现的组件
1)首先创建一个maven主工程。
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。
pom文件如下:
<?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.eBao</groupId>
<artifactId>SpringCloudPom</artifactId>
<version>1.0-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>server</module>
<module>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)创建2个model工程:一个model工程作为Eureka Server,另一个作为Eureka Client。
server创建如下:
右键工程->创建model-> 选择spring initialir->下一步(填写项目名)->下一步(选择cloud discovery->eureka server) ,然后一直下一步就行了。
创建完成后查看创建的model中pom含有spring-cloud-starter-netflix-eureka-server的依赖即可,无需自己引入。
pom文件如下:
<?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.example</groupId>
<artifactId>server</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>server</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.0.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<!-- <modules>
<module>eureka-server</module>
<module>service-hi</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>Greenwich.M1</spring-cloud.version>
</properties>
<dependencies>
<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-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>
<repositories>
<repository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
</repositories>
</project>
3)启动服务中心server
一个注解@EnableEurekaServer,这个注解需要在springboot工程的启动application类上加:
package com.example.server;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;
@SpringBootApplication
@EnableEurekaServer
public class ServerApplication {
public static void main(String[] args) {
SpringApplication.run(ServerApplication.class, args);
}
}
4)eureka server的配置文件appication.properties
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。
server.port=8761
#当前实例的主机名称
eureka.instance.hostname=localhost
#false代表不向注册中心注册自己(因为本身就是注册中心),默认是true,如果不设为false,启动会报找不到注册中心的错误
eureka.client.register-with-eureka=false
#注册中心用于维护服务实例,无需检索服务,故设为false
eureka.client.fetch-registry=false
eureka.client.serviceUrl.defaultZone=http://${eureka.instance.hostname}:${server.port}/eureka/
5)启动工程、打开浏览器访问:http://localhost:8761 ,界面如下:
No application available 没有服务被发现、因为没有注册服务
6)现在来创建一个服务 (eureka client)
创建过程同server类似:
右键工程->创建model-> 选择spring initialir->下一步(填写项目名)->下一步(选择cloud discovery->eureka Discovery) ,然后一直下一步就行了。
创建完成后查看创建的model中pom含有spring-cloud-starter-netflix-eureka-client的依赖即可,无需自己引入。
pom文件如下、这里引入了spring-boot-starter-web的依赖:
<?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>com.example</groupId>
<artifactId>client</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>client</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.0.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>
<spring-cloud.version>Greenwich.M1</spring-cloud.version>
</properties>
<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-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring-cloud.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
<repositories>
<repository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
</repositories>
</project>
7)通过注解@EnableEurekaClient 表明自己是一个eureka-client
package com.example.client;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
@SpringBootApplication
@EnableEurekaClient
@RestController
public class ClientApplication {
public static void main(String[] args) {
SpringApplication.run(ClientApplication.class, args);
}
@Value("${server.port}")
String port;
@RequestMapping("/hi")
public String home(@RequestParam(value = "name", defaultValue = "forezp") String name) {
return "hi " + name + " ,i am from port:" + port;
}
}
还需要在配置文件中注明自己的服务注册中心的地址,application.properties配置文件如下:
server.port=8762
spring.application.name=service-hi
eureka.client.serviceUrl.defaultZone=http://localhost:8761/eureka/
8)启动工程,打开http://localhost:8761 ,即eureka server 的网址:
你会发现一个服务已经注册在服务中了,服务名为SERVICE-HI ,端口为7862
这时打开 http://localhost:8762/hi?name=forezp ,你会在浏览器上看到 :
hi forezp,i am from port:8762
注:
这里可以启动多个实例
启动eureka-server 工程;启动service-hi工程,它的端口为8762;将service-hi的配置文件的端口改为8763,并启动,这时你会发现:service-hi在eureka-server注册了2个实例,这就相当于一个小的集群。
如何在IDEA启动多个实例:
点击Edit Configuration
打开配置后,将默认的Single instance only(单实例)的钩去掉即可