学习微服务的服务注册与发现——EurekaServer与EurekaClient

微服务项目通常会存在多个服务，但服务与服务之间的调用，联调就用到了服务注册与发现，spring cloud全家桶就包含了Eureka来实现这个功能。

1.首先建立服务注册中心 利用spring Initializr来建立项目，new Module->选中Spring Initializr->Next

而后填写项目名称，以及maven项目仍是gradle 项目

最后选择要用到何种依赖，此时选择的服务发现的eureka-server

到此项目就构建完成了，此时的build.gradle文件是这样的：

buildscript {
	ext {
		springBootVersion = '2.0.4.RELEASE'
	}
	repositories {
		mavenCentral()
	}
	dependencies {
		classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
	}
}

apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'org.springframework.boot'
apply plugin: 'io.spring.dependency-management'

group = 'com.example'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = 1.8

repositories {
	mavenCentral()
}


ext {
	springCloudVersion = 'Finchley.SR1'
}

dependencies {
	compile('org.springframework.cloud:spring-cloud-starter-netflix-eureka-server')
	testCompile('org.springframework.boot:spring-boot-starter-test')
}

dependencyManagement {
	imports {
		mavenBom "org.springframework.cloud:spring-cloud-dependencies:${springCloudVersion}"
	}
}

项目布局是这样的：

启动主方法所在类EurekaServerApplication.java

package com.example.eurekaserver;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;


@EnableEurekaServer
@SpringBootApplication
public class EurekaServerApplication {

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

而后启动一个服务注册中心，在EurekaServerApplication类上面加一个注解@EnableEurekaServer；

application.yml配置文件：

server:
    port: 8791


spring:
  application:
    name: eureka-server


eureka:
  instance:
    hostname: localhost
  client:
    register-with-eureka: false   #由于默认状况下一个eureka-server也是一个eureka-client,因此设置注册eureka为false
    fetch-registry: false
    service-url:
      defalutZone: http://localhost:8791/eureka

而后启动该项目,访问http://localhost:8791,此时标明尚未服务注册进来

 

2.建立服务提供者 eureka-client

build.gradle文件，增长了eureka-client依赖

buildscript {
	ext {
		springBootVersion = '2.0.4.RELEASE'
	}
	repositories {
		mavenCentral()
	}
	dependencies {
		classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
	}
}

apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'org.springframework.boot'
apply plugin: 'io.spring.dependency-management'

group = 'com.example'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = 1.8

repositories {
	mavenCentral()
}


ext {
	springCloudVersion = 'Finchley.SR1'
}


dependencies {
	compile('org.springframework.boot:spring-boot-starter')
	compile('org.springframework.boot:spring-boot-starter-web')
	compile('org.springframework.cloud:spring-cloud-starter-netflix-eureka-client')
	testCompile('org.springframework.boot:spring-boot-starter-test')
}

dependencyManagement {
	imports {
		mavenBom "org.springframework.cloud:spring-cloud-dependencies:${springCloudVersion}"
	}
}

启动类EurekaClientSayHiApplication.java文件

package com.example.eurekaclientsayhi;

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.RestController;

@RestController
@EnableEurekaClient
@SpringBootApplication
public class EurekaClientSayHiApplication {

	public static void main(String[] args) {
		SpringApplication.run(EurekaClientSayHiApplication.class, args);
	}



	@RequestMapping("/hi")
	public String sayHi(){
		return "hi";
	}
}

application.yml文件

server:
  port: 8792


spring:
  application:
    name: eureka-client-say-hi


eureka:
  client:
    service-url:
      defaultZone: http://localhost:8791/eureka/   #eureka-server的地址

启动该eureka-client项目：

访问http://localhost:8792/hi

此时刷新一下地址：http://localhost:8791   ，发现已经有服务注册到服务注册中心了。