Spring Cloud Alibaba 2.2 服务消费者(Ribbon)

逃离我推掉我的手 2022-12-28 07:15 131阅读 0赞

### 文章目录 ###

*   *   *  1 摘要
         *  2 核心 Maven 依赖
         *  3 核心代码
         *   *  3.1 application 配置文件
             *  3.2 Service 层-服务调用
             *  3.3 Controller 控制层
             *  3.5 SpringBoot 启动类
             *  3.6 其他相关代码
         *  4 请求测试
         *   *  4.1 GET 方式请求接口
             *  4.2 POST 方式请求接口
         *  5 推荐参考资料
         *  6 Github 源码

### 1 摘要 ###

本文将介绍基于 Spring Cloud Alibaba 2.2 使用 RestTemplete(Ribbon)搭建服务消费者。

### 2 核心 Maven 依赖 ###

./cloud-alibaba-server-consumer/pom.xml

<dependencies>
            
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
                <version>${spring-cloud-alibaba.version}</version>
            </dependency>
            
            
    
        </dependencies>
    
        <dependencyManagement>
            <dependencies>
                <dependency>
                    <groupId>com.alibaba.cloud</groupId>
                    <artifactId>spring-cloud-alibaba-dependencies</artifactId>
                    <version>${spring-cloud-alibaba.version}</version>
                    <type>pom</type>
                    <scope>import</scope>
                </dependency>
            </dependencies>
        </dependencyManagement>

其中 `${spring-cloud-alibaba.version}` 的版本为 `2.2.3.RELEASE`

**注意事项**: Spring Cloud Alibaba 2.2.3.RELEASE 版本支持的 Spring Boot 版本为 `2.3.1.RELEASE` ，建议在搭建项目时要保持版本的一致性，Spring Boot 版本过高或过低都可能导致不兼容问题

### 3 核心代码 ###

#### 3.1 application 配置文件 ####

./cloud-alibaba-server-consumer/src/main/resources/application.yml

## config
    
    ## server
    server:
      port: 8602
    
    ## spring
    spring:
      application:
        name: cloud-alibaba-server-consumer
      cloud:
        nacos:
          discovery:
            server-addr: 172.16.140.10:8688
    
    ## endpoint
    management:
      endpoints:
        web:
          exposure:
            include: "*"

#### 3.2 Service 层-服务调用 ####

Service 接口

./cloud-alibaba-server-consumer/src/main/java/com/ljq/demo/springboot/alibaba/server/consumer/service/NacosConsumerService.java

package com.ljq.demo.springboot.alibaba.server.consumer.service;
    
    import com.ljq.demo.springboot.alibaba.server.consumer.model.param.HelloParam;
    
    /** * @Description: Nacos 服务消费者业务层 * @Author: junqiang.lu * @Date: 2020/12/2 */
    public interface NacosConsumerService { 
    
        /** * hello * * @param helloParam * @return */
        String hello(HelloParam helloParam);
    
        /** * 回复 * * @param helloParam * @return */
        String replay(HelloParam helloParam);
    }

Service 实现类

./cloud-alibaba-server-consumer/src/main/java/com/ljq/demo/springboot/alibaba/server/consumer/service/impl/NacosConsumerServiceImpl.java

package com.ljq.demo.springboot.alibaba.server.consumer.service.impl;
    
    import com.ljq.demo.springboot.alibaba.server.consumer.common.constant.NacosConst;
    import com.ljq.demo.springboot.alibaba.server.consumer.model.param.HelloParam;
    import com.ljq.demo.springboot.alibaba.server.consumer.service.NacosConsumerService;
    import lombok.extern.slf4j.Slf4j;
    import org.springframework.http.ResponseEntity;
    import org.springframework.stereotype.Service;
    import org.springframework.util.CollectionUtils;
    import org.springframework.web.client.RestTemplate;
    
    import javax.annotation.Resource;
    import java.util.HashMap;
    import java.util.Map;
    
    /** * @Description: Nacos 服务消费者业务实现类 * @Author: junqiang.lu * @Date: 2020/12/2 */
    @Slf4j
    @Service("nacosConsumerService")
    public class NacosConsumerServiceImpl implements NacosConsumerService { 
    
        private static final String HELLO_URL = "/api/nacos/hello";
        private static final String REPLAY_URL = "/api/nacos/replay";
    
        @Resource
        private RestTemplate template;
    
        /** * hello * * @param helloParam * @return */
        @Override
        public String hello(HelloParam helloParam) { 
            Map<String, Object> param = new HashMap<>(16);
            param.put("name", helloParam.getName());
            String url = convertGetUrl(NacosConst.NACOS_SERVER_PROVIDER_NAME, HELLO_URL, param);
            ResponseEntity<String> response = template.getForEntity(url, String.class);
            log.info("response: {}", response.getBody());
            return response.getBody();
        }
    
        /** * 回复 * * @param helloParam * @return */
        @Override
        public String replay(HelloParam helloParam) { 
            String url = convertGetUrl(NacosConst.NACOS_SERVER_PROVIDER_NAME, REPLAY_URL, null);
            ResponseEntity<String> response = template.postForEntity(url, helloParam, String.class);
            log.info("response: {}", response.getBody());
            return response.getBody();
        }
    
        /** * 组装 Get 请求 URL * @param serverName 服务名称 * @param apiAddress 接口地址 * @param param 请求参数 * @return */
        private String convertGetUrl(String serverName, String apiAddress, Map<String, Object> param) { 
            StringBuilder urlBuilder = new StringBuilder("http://");
            urlBuilder.append(serverName).append(apiAddress);
            if (!CollectionUtils.isEmpty(param)) { 
                urlBuilder.append("?");
                param.forEach((k, v) -> { 
                    urlBuilder.append(k).append("=").append(v).append("&");
                });
                urlBuilder.deleteCharAt(urlBuilder.lastIndexOf("&"));
            }
            return urlBuilder.toString();
        }
    
    
    }

使用 Spring 提供的 RestTemplate 请求微服务，这里的 RestTemplate 是经过负载均衡的，实际发送的请求会解析为服务，而非将服务名作为域名进行请求，**负载均衡配置在SpringBoot 启动类中**

#### 3.3 Controller 控制层 ####

./cloud-alibaba-server-consumer/src/main/java/com/ljq/demo/springboot/alibaba/server/consumer/controller/NacosConsumerController.java

package com.ljq.demo.springboot.alibaba.server.consumer.controller;
    
    import com.ljq.demo.springboot.alibaba.server.consumer.model.param.HelloParam;
    import com.ljq.demo.springboot.alibaba.server.consumer.service.NacosConsumerService;
    import lombok.extern.slf4j.Slf4j;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.http.MediaType;
    import org.springframework.http.ResponseEntity;
    import org.springframework.web.bind.annotation.*;
    
    /** * @Description: Nacos 服务消费者控制层 * @Author: junqiang.lu * @Date: 2020/12/1 */
    @Slf4j
    @RestController
    @RequestMapping("/api/nacos/consumer")
    public class NacosConsumerController { 
    
        @Autowired
        private NacosConsumerService consumerService;
      
        @GetMapping(value = "/hello", produces = { MediaType.APPLICATION_JSON_VALUE})
        public ResponseEntity<String> sayHello(HelloParam helloParam) { 
            String result = consumerService.hello(helloParam);
            return ResponseEntity.ok(result);
        }
    
        @PostMapping(value = "/replay", produces = { MediaType.APPLICATION_JSON_VALUE})
        public ResponseEntity<String> replay(@RequestBody HelloParam helloParam) { 
            String result = consumerService.replay(helloParam);
            return ResponseEntity.ok(result);
        }
    }

#### 3.5 SpringBoot 启动类 ####

./cloud-alibaba-server-consumer/src/main/java/com/ljq/demo/springboot/alibaba/server/consumer/CloudAlibabaServerConsumerApplication.java

package com.ljq.demo.springboot.alibaba.server.consumer;
    
    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;
    
    /** * @author junqiang.lu */
    @EnableDiscoveryClient
    @SpringBootApplication
    public class CloudAlibabaServerConsumerApplication { 
    
        public static void main(String[] args) { 
            SpringApplication.run(CloudAlibabaServerConsumerApplication.class, args);
        }
    
        @Bean
        @LoadBalanced
        public RestTemplate restTemplate() { 
            return new RestTemplate();
        }
    
    }

简要代码说明:

`@EnableDiscoveryClient`: spring cloud 服务发现注解，使用该注解可以在服务注册中心发现、管理该服务

`@Bean`: 将对象注册为 Spring 的一个 Bean，通过 Spring 来管理其生命周期

`@LoadBalanced` ： Ribbon 的负载均衡注解,简单来说其作用就是对请求的URI进行转换获取到具体应该请求哪个服务实例ServiceInstance

关于 `Ribbon` 的 `@LoadBalanced` 注解,其作用是实现客户端负载均衡，具体说明可参考:

[由springcloud ribbon的 @LoadBalanced注解的使用理解][springcloud ribbon_ _LoadBalanced]

#### 3.6 其他相关代码 ####

定义服务名称的常量类

./cloud-alibaba-server-consumer/src/main/java/com/ljq/demo/springboot/alibaba/server/consumer/common/constant/NacosConst.java

package com.ljq.demo.springboot.alibaba.server.consumer.common.constant;
    
    /** * @Description: Nacos 相关常量 * @Author: junqiang.lu * @Date: 2020/12/2 */
    public class NacosConst { 
    
        private NacosConst() { 
        }
    
        public static final String NACOS_SERVER_PROVIDER_NAME = "cloud-alibaba-server-provider";
    }

请求参数接收类

./cloud-alibaba-server-consumer/src/main/java/com/ljq/demo/springboot/alibaba/server/consumer/model/param/HelloParam.java

package com.ljq.demo.springboot.alibaba.server.consumer.model.param;
    
    import lombok.Data;
    
    import java.io.Serializable;
    
    /** * @Description: 用户实体类 * @Author: junqiang.lu * @Date: 2020/12/2 */
    @Data
    public class HelloParam implements Serializable { 
    
        /** * 用户名 */
        private String name;
    }

### 4 请求测试 ###

依次启动服务提供者项目 `cloud-alibaba-server-provider`，服务消费者项目 `cloud-alibaba-server-consumer`

打开 Nacos 控制台，可以看到两个服务

![Nacos 控制台][Nacos]

请求服务消费者的接口

#### 4.1 GET 方式请求接口 ####

接口地址与请求参数:

http://127.0.0.1:8602/api/nacos/consumer/hello?name=%E5%BE%B7%E7%8E%9B%E8%A5%BF%E4%BA%9A

请求方式: GET

返回结果:

Hello,德玛西亚

服务消费者日志:

2020-12-15 11:07:01.147  INFO 67805 --- [nio-8602-exec-1] l.d.s.a.s.c.s.i.NacosConsumerServiceImpl : response: Hello,德玛西亚

服务提供者日志:

2020-12-15 11:07:01.105  INFO 67789 --- [nio-8600-exec-1] c.l.d.p.a.s.p.c.NacosProviderController  : serverPort: 8600
    2020-12-15 11:07:01.105  INFO 67789 --- [nio-8600-exec-1] c.l.d.p.a.s.p.c.NacosProviderController  : result: Hello,德玛西亚

#### 4.2 POST 方式请求接口 ####

接口地址:

http://127.0.0.1:8602/api/nacos/consumer/replay

请求参数:

{ 
        "name": "卢本伟"
    }

请求方式: POST

返回结果:

Hi,卢本伟,I'm fine,Thank you.

服务消费者日志:

2020-12-15 11:10:18.759  INFO 67805 --- [nio-8602-exec-3] l.d.s.a.s.c.s.i.NacosConsumerServiceImpl : response: Hi,卢本伟,I'm fine,Thank you.

服务提供者日志:

2020-12-15 11:10:18.757  INFO 67789 --- [nio-8600-exec-3] c.l.d.p.a.s.p.c.NacosProviderController  : result: Hi,卢本伟,I'm fine,Thank you.

至此，一个基于 Spring Cloud Alibaba 2.2 的服务消费者框架已经搭建完成

### 5 推荐参考资料 ###

[官方文档: Spring Cloud Alibaba Nacos Discovery][Spring Cloud Alibaba Nacos Discovery]

[Spring Cloud Alibaba系列教程 - Spring Cloud Alibaba 创建服务消费者][Spring Cloud Alibaba_ - Spring Cloud Alibaba]

### 6 Github 源码 ###

**Gtihub 源码地址** : [https://github.com/Flying9001/springBootDemo][https_github.com_Flying9001_springBootDemo]

个人公众号:**404Code**,分享半个互联网人的技术与思考，感兴趣的可以关注.  
![404Code][]

[springcloud ribbon_ _LoadBalanced]: https://blog.csdn.net/xiao_jun_0820/article/details/78917215
[Nacos]: /images/20221120/11fabc1fff4f46d480c2952f5e5a44dc.png
[Spring Cloud Alibaba Nacos Discovery]: https://github.com/alibaba/spring-cloud-alibaba/wiki/Nacos-discovery
[Spring Cloud Alibaba_ - Spring Cloud Alibaba]: https://www.jianshu.com/p/9cdcad44e53e
[https_github.com_Flying9001_springBootDemo]: https://github.com/Flying9001/springBootDemo
[404Code]: /images/20221120/7379456f6d7b408586792286975a4942.png