springCloud - 第3篇 - 消费者调用服务 ( RestTemplate + Ribbon )

Dear 丶 2021-11-27 00:54 323阅读 0赞

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一、新建 ribbon 工程：

1. file - new - module

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTEzMTQ0NDI_size_16_color_FFFFFF_t_70][]

2. spring Initializr - module SDK 选择自己的 JDK ，其余的可以不用填写，next。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTEzMTQ0NDI_size_16_color_FFFFFF_t_70 1][]

3. 填写工程相关信息：包名、工程名等，next。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTEzMTQ0NDI_size_16_color_FFFFFF_t_70 2][]

4. spring cloud discovery - 勾选 eureka discover client，next。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTEzMTQ0NDI_size_16_color_FFFFFF_t_70 3][]

或  spring cloud routing - 勾选 ribbon，next。（此步这 2 种都可）

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTEzMTQ0NDI_size_16_color_FFFFFF_t_70 4][]

5. 工程名，代码存放位置等，finish 。

![20190723135503278.png][]

6. 工程结构如下：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTEzMTQ0NDI_size_16_color_FFFFFF_t_70 5][]

7. pom.xml：

<?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.ribbon</groupId>
        <artifactId>service-ribbon</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <packaging>jar</packaging>
        <name>service-ribbon</name>
        <description>服务消费 ribbon 方式</description>
    
        <parent>
            <groupId>com.base</groupId>
            <artifactId>base-config</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </parent>
    
        <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>
    
        <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>

8. 在工程启动类上加注解：@EnableDiscoveryClient  。

关于 2 个注解的区别见文章：[springcloud 注解 @EnableDiscoveryClient 与 @EnableEurekaClient 的区别][springcloud _ _EnableDiscoveryClient _ _EnableEurekaClient]

package com.ribbon.serviceribbon;
    
    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.context.annotation.Bean;
    import org.springframework.web.client.RestTemplate;
    
    // 标明自已为服务
    @EnableDiscoveryClient
    
    @SpringBootApplication
    public class ServiceRibbonApplication {
    
    
        public static void main(String[] args) {
            SpringApplication.run(ServiceRibbonApplication.class, args);
        }
    
        /**
         * 向 ioc 注入 bean : restTemplate;
         * 注解 @LoadBalanced ：此 bean 开启负载均衡。
         * @return
         */
        @Bean
        @LoadBalanced
        RestTemplate restTemplate() {
            return new RestTemplate();
        }
    }

实现对于生产者服务的调用：

SeeParamService

package com.ribbon.serviceribbon;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Service;
    import org.springframework.web.client.RestTemplate;
    
    /**
     * @author yujiang
     * @description
     * @date 2019/7/22 11:45
     */
    @Service
    public class SeeParamService {
    
        @Autowired
        RestTemplate restTemplate;
    
        public String seeService(String param) {
            return restTemplate.getForObject("http://see-param/seeParam?param=" + param, String.class);
        }
    
    }

SeeParamController：

package com.ribbon.serviceribbon;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestParam;
    import org.springframework.web.bind.annotation.RestController;
    
    /**
     * /**
     *
     * @author yujiang
     * @description
     * @date 2019/7/22 13:27
     */
    @RestController
    public class SeeParamController {
    
    
        @Autowired
        SeeParamService seeParamService;
    
        @RequestMapping(value = "/seeParam")
        public String see(@RequestParam String param) {
            return seeParamService.seeService(param);
        }
    }

9. 配置文件相关设置：

# 注册中心 - 端口： 1234、工程名： eureka （见 eureka 工程中配置）。
    eureka.client.serviceUrl.defaultZone= http://localhost:1234/eureka/
    
    # 端口
    server.port= 8701
    
    # 工程名
    spring.application.name= ribbon

10.启动工程：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTEzMTQ0NDI_size_16_color_FFFFFF_t_70 6][]

11. 浏览器访问：  [http://localhost:8701/seeParam?param=][http_localhost_8701_seeParam_param]参数啊 。刷新多次请求，得到不同端口服返回的结果 。

![20190723143206548.png][]![20190723143101524.png][]

![20190723143320741.png][]

12. 从注册中心可知，当前注册了4 个服务，访问注册中心：[http://localhost:1234/][http_localhost_1234]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTEzMTQ0NDI_size_16_color_FFFFFF_t_70 7][]

13. 不断刷新 ribbon 工程访问地址，可见 8801、8802、8803 都有请求到。图见第 11 点。

说明 负载均衡 已实现，消费者（服务请求方应用）请求到了不同的生产者（服务提供方应用）。

14.总结：

此时 整个工程体系为：

1个注册中心：eureka 工程，端口：1234 。

3个生产者 see-param ，分别占用端口：8801、8802、8803 ，三者都向 eureka  注册，暴露自已提供的服务。

1个消费者 ribbon 工程，端口：8701 。向 eureka 注册 ，订阅自已所需要的服务。

ribbon 有作负载均衡，故 在调用生产者服务时，可轮流请求到不同的生产者服务。

\------------------------------------------------------------------------------

遇到 问题1：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTEzMTQ0NDI_size_16_color_FFFFFF_t_70 8][]

解决方法见文章：[解决：There was an unexpected error (type=Internal Server Error,..). No instances available for XXX][There was an unexpected error _type_Internal Server Error_.._. No instances available for XXX]

遇到 问题2 ：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTEzMTQ0NDI_size_16_color_FFFFFF_t_70 9][]

解决方法见文章：[解决：Whitelabel Error Page This application has no explicit mapping for /error...UnknownHostException][Whitelabel Error Page This application has no explicit mapping for _error...UnknownHostException]

\------------------------------------------------------------------------

下一篇：[springCloud - 第4篇 - 消费者调用服务 ( Feign )][springCloud - _4_ - _ _ Feign]

源码见：[https://gitee.com/FJ\_WoMenDeShiJie/springcloud-ribbon][https_gitee.com_FJ_WoMenDeShiJie_springcloud-ribbon]

\--------------------------------------------------------------

PS：这个系列不定时更新，只是个人的学习分享，

内容全程参考书目：

《Spring Cloud 与 Docker 微服务架构空实战 》、

《Spring Cloud 微服务实战》及此书作者博客：http://blog.didispace.com/spring-cloud-learning/

《深入理解 Spring Cloud 与微服务构建》及此书作者博客：https://blog.csdn.net/forezp/article/details/70148833  
\--------------------------------------------------------------

[Link 1]: https://www.captainai.net/jiangyu1013/
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTEzMTQ0NDI_size_16_color_FFFFFF_t_70]: /images/20211126/da724cbde7bb40e098da9698e5b575c9.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTEzMTQ0NDI_size_16_color_FFFFFF_t_70 1]: /images/20211126/92c1d7bc7a2d46189c149292736add94.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTEzMTQ0NDI_size_16_color_FFFFFF_t_70 2]: /images/20211126/a13535c98b4d4ddd83a70bc00b1bf0e5.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTEzMTQ0NDI_size_16_color_FFFFFF_t_70 3]: /images/20211126/90dc0559b9064dbe93afe3ae03495a9c.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTEzMTQ0NDI_size_16_color_FFFFFF_t_70 4]: /images/20211126/43937b75ded54a388415d56a3f8f0830.png
[20190723135503278.png]: /images/20211126/39685d8280f5419fa873931554c9eff7.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTEzMTQ0NDI_size_16_color_FFFFFF_t_70 5]: /images/20211126/f43f7d2bedfa466196e7a4d154caba04.png
[springcloud _ _EnableDiscoveryClient _ _EnableEurekaClient]: https://blog.csdn.net/jiangyu1013/article/details/96828681
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTEzMTQ0NDI_size_16_color_FFFFFF_t_70 6]: /images/20211126/7c259d3851d94969b8f18367dd20d974.png
[http_localhost_8701_seeParam_param]: http://localhost:8701/seeParam?param=%E5%8F%82%E6%95%B0%E5%95%8A
[20190723143206548.png]: https://img-blog.csdnimg.cn/20190723143206548.png
[20190723143101524.png]: /images/20211126/fb2d93a349484e08a4b5b33536ee7e12.png
[20190723143320741.png]: /images/20211126/d01a588627544957add58af414df100f.png
[http_localhost_1234]: http://localhost:1234/
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTEzMTQ0NDI_size_16_color_FFFFFF_t_70 7]: /images/20211126/3158beb780fe4368815e74cbd965439e.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTEzMTQ0NDI_size_16_color_FFFFFF_t_70 8]: /images/20211126/b48b35eb4f7d4cb2a35c0f5b876081e1.png
[There was an unexpected error _type_Internal Server Error_.._. No instances available for XXX]: https://blog.csdn.net/jiangyu1013/article/details/96978665
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTEzMTQ0NDI_size_16_color_FFFFFF_t_70 9]: /images/20211126/55551581186c43499babc85074cb1679.png
[Whitelabel Error Page This application has no explicit mapping for _error...UnknownHostException]: https://blog.csdn.net/jiangyu1013/article/details/97015963
[springCloud - _4_ - _ _ Feign]: https://blog.csdn.net/jiangyu1013/article/details/97034095
[https_gitee.com_FJ_WoMenDeShiJie_springcloud-ribbon]: https://gitee.com/FJ_WoMenDeShiJie/springcloud-ribbon