【微服务架构 - 08 - Spring Cloud】04 创建服务消费者（Ribbon)

系统管理员 2022-03-22 15:20 220阅读 0赞

## 概述 ##

--------------------

在微服务架构中，业务都会被拆分成一个独立的服务，服务与服务的通讯是基于 http restful 的。Spring Cloud 有两种服务调用方式，一种是 ribbon + restTemplate，另一种是 feign。

## Ribbon 简介 ##

--------------------

Ribbon 是一个负载均衡客户端，可以很好的控制 `http` 和 `top` 的一些行为。

## 准备工作 ##

--------------------

*  启动服务提供者 `hello-spring-cloud-service-admin`，端口号为：`8762`
 *  修改配置文件的端口号为：`8763`，启动后在 Eureka 中会注册两个实例，这相当于一个小集群

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3NTgxMjgy_size_16_color_FFFFFF_t_70]

## 创建服务消费者 ##

--------------------

创建一个工程名为 `hello-spring-cloud-web-admin-ribbon` 的服务消费者项目，  
`pom.xml` 配置如下：

<?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>
    
        <parent>
            <groupId>com.yuu</groupId>
            <artifactId>hello-spring-cloud-dependencies</artifactId>
            <version>1.0.0-SNAPSHOT</version>
            <relativePath>../hello-spring-cloud-dependencies/pom.xml</relativePath>
        </parent>
    
        <artifactId>hello-spring-cloud-web-admin-ribbon</artifactId>
        <packaging>jar</packaging>
    
        <name>hello-spring-cloud-web-admin-ribbon</name>
        <inceptionYear>2019-Now</inceptionYear>
    
        <dependencies>
            
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-tomcat</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-thymeleaf</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-actuator</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <scope>test</scope>
            </dependency>
            
    
            
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
            </dependency>
            
    
            
            <dependency>
                <groupId>net.sourceforge.nekohtml</groupId>
                <artifactId>nekohtml</artifactId>
            </dependency>
        </dependencies>
    
        <build>
            <plugins>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                    <configuration>
                        <mainClass>com.yuu.hello.spring.cloud.web.admin.ribbon.WebAdminRibbonApplication</mainClass>
                    </configuration>
                </plugin>
            </plugins>
        </build>
    </project>

主要是增加了 Ribbon 的依赖

<dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
    </dependency>

## Application ##

--------------------

通过 `@EnableDiscoveryClient` 注解注册到服务中心

package com.yuu.hello.spring.cloud.service.admin;
    
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
    
    /**
     * @Classname ServiceAdminApplication
     * @Date 2019/1/28 22:50
     * @Created by Yuu
     */
    @SpringBootApplication
    @EnableEurekaClient
    public class ServiceAdminApplication {
        public static void main(String[] args) {
            SpringApplication.run(ServiceAdminApplication.class, args);
        }
    }

## application.yml ##

设置程序端口号为：`8764`

spring:
      application:
        name: hello-spring-cloud-service-admin
    
    server:
      port: 8763
    eureka:
      client:
        servcieUrl:
          defaultZone: http://localhost:8761/eureka/

## Configuration ##

配置注入 `RestTemplate` 的 `Bean`，并通过 `@LoadBalanced` 注解表明开启负载均衡功能

package com.yuu.hello.spring.cloud.web.admin.ribbon.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;
    
    /**
     * @Classname RestTemplateConfiguration
     * @Date 2019/1/29 0:08
     * @Created by Yuu
     */
    @Configuration
    public class RestTemplateConfiguration {
    
        @Bean
        @LoadBalanced
        public RestTemplate restTemplate() {
            return new RestTemplate();
        }
    }

## 创建测试用的 Service ##

--------------------

在这里我们直接用的程序名替代了具体的 URL 地址，在 Ribbon 中它会根据服务名来选择具体的服务实例，根据服务实例在请求的时候会用具体的 URL 替换掉服务名，代码如下：

package com.yuu.hello.spring.cloud.web.admin.ribbon.service;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Service;
    import org.springframework.web.client.RestTemplate;
    
    /**
     * @Classname AdminService
     * @Date 2019/1/29 0:09
     * @Created by Yuu
     */
    @Service
    public class AdminService {
    
        @Autowired
        private RestTemplate restTemplate;
    
        public String sayHi(String message) {
            return restTemplate.getForObject("http://HELLO-SPRING-CLOUD-SERVICE-ADMIN/hi?message=" + message, String.class);
        }
    }

## 创建测试用的 Controller ##

--------------------

package com.yuu.hello.spring.cloud.web.admin.ribbon.controller;
    
    import com.yuu.hello.spring.cloud.web.admin.ribbon.service.AdminService;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestMethod;
    import org.springframework.web.bind.annotation.RequestParam;
    import org.springframework.web.bind.annotation.RestController;
    
    /**
     * @Classname AdminController
     * @Date 2019/1/29 0:14
     * @Created by Yuu
     */
    @RestController
    public class AdminController {
    
        @Autowired
        private AdminService adminService;
    
        @RequestMapping(value = "hi", method = RequestMethod.GET)
        public String sayHi(@RequestParam(value = "message") String message) {
            return adminService.sayHi(message);
        }
    }

## 测是访问 ##

在浏览器上多次访问 [http://localhost:8764/hi?message=HelloSpringCloud][http_localhost_8764_hi_message_HelloSpringCloud]

浏览器交替显示：

![在这里插入图片描述][20190129115437986.png]  
![在这里插入图片描述][20190129115453682.png]

## 附 ##

--------------------

## 在 IDEA 中配置一个工程启动多个实例 ##

#### 步骤一 ####

点击 `Run` \-> `Edit Configurations...`

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3NTgxMjgy_size_16_color_FFFFFF_t_70 1]

#### 步骤二 ####

选择需要启动多实例的项目并勾选 `Allow running in parallel`

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3NTgxMjgy_size_16_color_FFFFFF_t_70 2]

## 步骤三 ##

通过修改 `application.yml` 配置文件的 `server.port` 的端口，启动多个实例，需要多个端口，分别进行启动即可。

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3NTgxMjgy_size_16_color_FFFFFF_t_70]: /images/20220322/580388aa1b764d32b9bb4a3b6908be78.png
[http_localhost_8764_hi_message_HelloSpringCloud]: http://localhost:8764/hi?message=HelloSpringCloud
[20190129115437986.png]: /images/20220322/9737aa6cd8834841a3a031cde1e9b85c.png
[20190129115453682.png]: /images/20220322/8e4e450d1db9475da96a2c62a1634f43.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3NTgxMjgy_size_16_color_FFFFFF_t_70 1]: /images/20220322/e4f52a1aa59e4a7298d070b637cde06d.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3NTgxMjgy_size_16_color_FFFFFF_t_70 2]: /images/20220322/1de8f5706e3442f9917ebaee66588304.png