1. Eureka 是什么

eureka 是一个服务注册的主键，业务的提供方、消费方可以注册到 EurekaServer ，然后服务的消费方可以通过服务的提供方的应用名进行资源消费（本节以 RestTemplate 进行远程调用，注意，使用服务名进行调用时，要在 RestTemplate 的 Bean 上加上 @LoadBalanced ，因为可能存在多个业务提供方使用相同的应用名，所以 RestTemplate 默认使用存在多个使用相同应用名的策略进行服务注册）

2. Eureka 的使用

2.1 编写相对应的 EurekaServer 代码

2.1.1 引入对应的 pom 依赖

    
        springcloud
        com.lidantao
        1.0-SNAPSHOT
    
    4.0.0

    cloud-eureka-server-7001

    
        8
        8
    

    
        
            org.springframework.cloud
            spring-cloud-starter-netflix-eureka-server
        

        
            org.springframework.boot
            spring-boot-starter-web
        

        
            org.springframework.boot
            spring-boot-starter-actuator
        
    

2.1.2 编写启动类

package com.lidantao;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;


@SpringBootApplication
@EnableEurekaServer
public class EurekaServerMain7001 {
    public static void main(String[] args) {
        SpringApplication.run(EurekaServerMain7001.class, args);
    }
}

2.1.3 yml 配置文件

server:
  port: 7001

eureka:
  instance:
    hostname: localhost # eureka 服务端的实例名称
    instance-id: eureka-server-7001
    prefer-ip-address: true
  client:
    register-with-eureka: false # false 表示不向注册中心注册自己
    fetch-registry: false # false 表示自己端是注册中心，我的职责就是维护服务实例，并不需要去检索服务
    service-url:
      # 设置与 Eureka server 交互的地址和注册服务都需要依赖这个地址
      defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/

2.2 编写相对应的 业务提供方-8001 代码

2.2.1 引入相对应的 pom 依赖

    
        springcloud
        com.lidantao
        1.0-SNAPSHOT
    
    4.0.0

    cloud-provider-8001

    
        
            org.springframework.boot
            spring-boot-starter-web
        

        
            org.springframework.boot
            spring-boot-starter-actuator
        

        
            org.projectlombok
            lombok
        

        
            org.springframework.cloud
            spring-cloud-starter-netflix-eureka-client
        
    

2.2.2 对应的业务代码

package com.lidantao.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;


@RestController
public class TestController {

    @Value("${server.port}")
    private String server_port;

    @RequestMapping("/provider/getTest")
    public String getTest(){
        return "getTest" + server_port;
    }


}

2.2.3 编写启动类

package com.lidantao;

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


@SpringBootApplication
public class ProviderMain8001 {
    public static void main(String[] args) {
        SpringApplication.run(ProviderMain8001.class, args);
    }
}

2.2.4 yml 配置文件

server:
  port: 8001

spring:
  application:
    name: provider
eureka:
  instance: # eureka 的主机名字
    instance-id: provider-8001
    # 悬浮显示 ip
    prefer-ip-address: true
  client:
    # true 表示向注册中心注册自己
    register-with-eureka: true
    # true 表示向 EurekaServer 拉取自己的注册信息
    fetch-registry: true
    service-url:
      defaultZone: http://localhost:7001/eureka

2.3 另一个 业务提供方-8002 代码

2.3.1 引入相对应 pom 依赖

    
        springcloud
        com.lidantao
        1.0-SNAPSHOT
    
    4.0.0

    cloud-provider-8001


    
        
            org.springframework.boot
            spring-boot-starter-web
        

        
            org.springframework.boot
            spring-boot-starter-actuator
        

        
            org.projectlombok
            lombok
        

        
            org.springframework.cloud
            spring-cloud-starter-netflix-eureka-client
        
    

2.3.2 编写相对应业务代码

package com.lidantao.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;


@RestController
public class TestController {

    @Value("${server.port}")
    private String server_port;

    @RequestMapping("/provider/getTest")
    public String getTest(){
        return "getTest" + server_port;
    }


}

2.3.3 启动类

package com.lidantao;

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


@SpringBootApplication
public class ProviderMain8002 {
    public static void main(String[] args) {
        SpringApplication.run(ProviderMain8002.class, args);
    }
}

2.3.4 yml 配置文件

server:
  port: 8002

spring:
  application:
    name: provider
eureka:
  instance: # eureka 的主机名字
    instance-id: provider-8002
    # 悬浮显示 ip
    prefer-ip-address: true
  client:
    # true 表示向注册中心注册自己
    register-with-eureka: true
    # true 表示向 EurekaServer 拉取自己的注册信息
    fetch-registry: true
    service-url:
      defaultZone: http://localhost:7001/eureka

2.4 编写 业务消费方 代码

2.4.1 引入相对应 pom 依赖

    
        springcloud
        com.lidantao
        1.0-SNAPSHOT
    
    4.0.0

    cloud-consumer-80

    
        8
        8
    

    
        
            org.springframework.boot
            spring-boot-starter-web
        

        
            org.springframework.boot
            spring-boot-starter-actuator
        

        
            org.projectlombok
            lombok
        

        
            org.springframework.cloud
            spring-cloud-starter-netflix-eureka-client
        
    

2.4.2 编写相对应业务代码

RestTemplate

package com.lidantao.config;

import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;


@Configuration
public class MyConfiguration {

    @Bean
    @LoadBalanced
    public RestTemplate restTemplate(){
        return new RestTemplate();
    }
}

 Controller 

package com.lidantao.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;


@RestController
public class TestController {

    @Autowired
    private RestTemplate restTemplate;

    //private String PROVIDER_URL = "http://127.0.0.1:8001/provider/getTest";
    private String PROVIDER_URL = "http://provider/provider/getTest";

    @RequestMapping("/consumer/getTest")
    public String getTest(){
        return restTemplate.getForObject(PROVIDER_URL, String.class);
    }


}

2.4.3 启动类

package com.lidantao;

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


@SpringBootApplication
public class ConsumerMain80 {
    public static void main(String[] args) {
        SpringApplication.run(ConsumerMain80.class, args);
    }
}

2.4.4 yml 配置文件

server:
  port: 80

spring:
  application:
    name: consumer
eureka:
  client:
    # true 表示向注册中心注册自己
    register-with-eureka: true
    # true 表示向 EurekaServer 拉取自己的注册信息
    fetch-registry: true
    service-url:
      defaultZone: http://localhost:7001/eureka
  instance:
    # eureka 的主机名字
    instance-id: consumer-80
    # 悬浮显示 ip
    prefer-ip-address: true

3. 父 pom 文件

    4.0.0

    com.lidantao
    springcloud
    pom
    1.0-SNAPSHOT
    
        cloud-provider-8001
        cloud-consumer-80
        cloud-eureka-server-7001
    

    
        UTF-8
        8
        8
        4.12
        1.2.17
        1.16.18
        5.1.47
        1.1.1
        1.3.2
    


    
        
            
            
                org.springframework.boot
                spring-boot-dependencies
                2.2.2.RELEASE
                pom
                import
            
            
            
                org.springframework.cloud
                spring-cloud-dependencies
                Hoxton.SR1
                pom
                import
            
            
            
                com.alibaba.cloud
                spring-cloud-alibaba-dependencies
                2.2.0.RELEASE
                pom
                import
            
        
    

4. Eureka 注册页面

5. 服务方消费结果（负载均衡效果）