Spring Cloud学习笔记2-服务消费者（rest+ribbon）

谁践踏了优雅 2022-04-04 11:16 219阅读 0赞

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title: “Spring Cloud学习笔记2-服务消费者（rest+ribbon）”

url: “[https://wsk1103.github.io/][https_wsk1103.github.io]”

tags:

*  Spring Cloud
 *  学习笔记

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#### 备注： ####

**官网**：[http://spring.io/projects/spring-cloud][http_spring.io_projects_spring-cloud]

**总纲**：[https://cloud.spring.io/spring-cloud-static/Finchley.SR2/single/spring-cloud.html][https_cloud.spring.io_spring-cloud-static_Finchley.SR2_single_spring-cloud.html]

**JAVA**： 1.8 +

**MAVEN**： 3.5.0 +

**Spring Boot**：2.0.7.RELEASE

**Spring Cloud**：Finchley

说明：Ribbon is a client-side load balancer that gives you a lot of control over the behavior of HTTP and TCP clients. Feign already uses Ribbon, so, if you use @FeignClient, this section also applies.

A central concept in Ribbon is that of the named client. Each load balancer is part of an ensemble of components that work together to contact a remote server on demand, and the ensemble has a name that you give it as an application developer (for example, by using the @FeignClient annotation). On demand, Spring Cloud creates a new ensemble as an ApplicationContext for each named client by using RibbonClientConfiguration. This contains (amongst other things) an ILoadBalancer, a RestClient, and a ServerListFilter.

Ribbon是一个客户端负载均衡器，可以让您对HTTP和TCP客户端的行为进行大量控制。Feign已使用Ribbon，因此，如果您使用@FeignClient，此部分也适用。

Ribbon中的一个核心概念是指定客户端的概念。每个负载均衡器都是一组组件的一部分，这些组件一起工作以按需联系远程服务器，并且该集合具有您作为应用程序开发人员提供的名称（例如，通过使用@FeignClient批注）。根据需要，Spring Cloud通过使用RibbonClientConfiguration为每个命名客户端创建一个新的集合作为ApplicationContext。这包含（除其他外）ILoadBalancer，RestClient和ServerListFilter。（谷歌翻译）

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本项目地址：[https://github.com/wsk1103/my-spring-cloud][https_github.com_wsk1103_my-spring-cloud]

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在开发过程中，基本上都会根据业务进行相应的拆分成为多个微服务。服务之间的通讯是基于http restful。Spring cloud有两种服务调用方式，一种是ribbon+restTemplate，另一种是feign（集成了ribbon+restTemplate）。

## 新增一个服务client2，用于模拟负载均衡。 ##

copy学习笔记1中的client，重新命名为client2，并且将端口修改8763。依次启动server，client，client2这3个服务。

可以在注册中心看到这2个服务已经注册了。

## 搭建Ribbon服务：ribbon ##

搭建方法同学习笔记1中新建module

#### 1. 修改pom文件 ####

<?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.wsk</groupId>
        <artifactId>ribbon</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <packaging>jar</packaging>
    
        <name>service-ribbon</name>
        <description>Demo project for Spring Boot</description>
    
        <parent>
            <groupId>my-spring-cloud</groupId>
            <artifactId>MySpringCloud</artifactId>
            <version>1.0-SNAPSHOT</version>
        </parent>
    
        <properties>
        </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-web</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
            </dependency>
        </dependencies>
    
        <build>
            <plugins>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                </plugin>
            </plugins>
        </build>
    
    
    </project>

#### 2. 重命名application.properties为application.yml ####

eureka:
      client:
        service-url:
          defaultZone: http://localhost:8761/eureka/
    
    server:
      port: 8764
    
    spring:
      application:
        name: service-ribbon

#### 3. 修改ServiceRibbonApplication ####

需要在ServiceRibbonApplication类上新增注解 **@EnableEurekaClient**  
和  
**@EnableDiscoveryClient**

package com.wsk.ribbon;
    
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
    import org.springframework.cloud.client.loadbalancer.LoadBalanced;
    import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
    import org.springframework.context.annotation.Bean;
    import org.springframework.web.client.RestTemplate;
    
    @SpringBootApplication
    @EnableEurekaClient
    //允许发现服务客户端
    @EnableDiscoveryClient
    public class ServiceRibbonApplication {
    
        public static void main(String[] args) {
            SpringApplication.run(ServiceRibbonApplication.class, args);
        }
    
        @Bean
        @LoadBalanced
        RestTemplate restTemplate() {
            return new RestTemplate();
        }
    }

#### 4. 新建包service -> 新建类HelloService ####

该类需要增加注解 **@Service**

package com.wsk.ribbon.service;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Service;
    import org.springframework.web.client.RestTemplate;
    
    /**
     * @author WuShukai
     * @version V1.0
     * @description
     * @date 2018/11/23  10:46
     */
    @Service
    public class HelloService {
    
        @Autowired
        RestTemplate restTemplate;
    
        public String hiService(String name) {
            //微服务调用
            return restTemplate.getForObject("http://SERVICE-CLIENT/hi?name="+name,String.class);
        }
    }

#### 5. 新建包controller -> 新建类HiController ####

访问该类中的方法的时候，该类会自动根据负载均衡的规则轮训注册中心的SERVICE-CLIENT。

package com.wsk.ribbon.controller;
    
    import com.wsk.ribbon.service.HelloService;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.RequestParam;
    import org.springframework.web.bind.annotation.RestController;
    
    /**
     * @author WuShukai
     * @version V1.0
     * @description
     * @date 2018/11/23  10:47
     */
    @RestController
    public class HiController {
        @Autowired
        private HelloService helloService;
    
        @GetMapping(value = "/hi")
        public String hi(@RequestParam String name) {
            return helloService.hiService( name );
        }
    }

#### 6. 启动ServiceRibbonApplication，多次访问http://localhost:8764/hi?name=sky ####

浏览器会交通显示：

hi sky,i am from port:8762
    
    hi sky,i am from port:8763

[https_wsk1103.github.io]: https://wsk1103.github.io/
[http_spring.io_projects_spring-cloud]: http://spring.io/projects/spring-cloud
[https_cloud.spring.io_spring-cloud-static_Finchley.SR2_single_spring-cloud.html]: https://cloud.spring.io/spring-cloud-static/Finchley.SR2/single/spring-cloud.html
[https_github.com_wsk1103_my-spring-cloud]: https://github.com/wsk1103/my-spring-cloud