SpringCloud系列之Ribbon｜胡萝虎的博客，群晖，NAS，电脑知识

在以往的文章中我们已经介绍了Spring Cloud框架中的Eureka（服务注册/发现）、Config（中心化配置管理）的简单使用，接下来将要介绍如何创建服务提供者、服务消费者，以及如何实现服务调用。在Spring Cloud中，服务间的RPC是通过Http实现的，服务提供者开放Restful接口，消费者可以使用RestTemplate或其他客户端调用接口。
在微服务系统中，服务启动后会注册到注册/发现服务器上，同时也会从注册/发现服务器上获取所需的服务列表。同一个服务可能会存在多个甚至数以十计百计个节点，这时候消费者如果还是通过简单的Http客户端消费服务，显然难以实现有效的负载均衡。那么Spring Cloud时如何处理服务调用的负载均衡的呢？

Ribbon

Ribbon时Netflix开发的负载均衡实现，默认支持轮询、随机等算法，使用者也可以自定义实现自己的算法。在Spring Cloud中可以和Eureka配合使用，从Eureka Server获取服务列表后，完成请求的负载均衡。

实战

创建主项目

为了演示方便，笔者将Eureka Server、Config Server、服务提供者和服务消费者都创建在一个大的Maven工程下，结构如下：

根目录下的pom.xml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>

    <groupId>com.huluohu.cloud</groupId>
    <artifactId>huluohu-spring-cloud-demo</artifactId>
    <version>1.0-SNAPSHOT</version>
    <modules>
        <module>eureka-server</module>
        <module>config-server-git</module>
        <module>provider-user</module>
        <module>consumer-movie</module>
    </modules>
    <packaging>pom</packaging>



    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.10.RELEASE</version>
    </parent>

    <properties>
        <java.version>1.8</java.version>
        <lombok.version>1.16.20</lombok.version>
        <spring-boot.version>1.5.10.RELEASE</spring-boot.version>
        <spring-cloud.version>Edgware.SR3</spring-cloud.version>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    </properties>

    <!--公共依赖-->
    <dependencies>
        <!--监控-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <!--Lombok-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>${lombok.version}</version>
        </dependency>
        <!--测试依赖-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>


    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Edgware.SR3</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <build>
        <pluginManagement>
            <plugins>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                    <version>${spring-boot.version}</version>
                    <executions>
                        <execution>
                            <goals>
                                <goal>build-info</goal>
                            </goals>
                        </execution>
                    </executions>
                </plugin>
                <plugin>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <configuration>
                        <target>${java.version}</target>
                        <source>${java.version}</source>
                        <encoding>UTF-8</encoding>
                    </configuration>
                </plugin>
            </plugins>
        </pluginManagement>
    </build>
</project>

创建服务提供者

这里以用户服务为例provider-user

pom.xml

<parent>
    <artifactId>huluohu-spring-cloud-demo</artifactId>
    <groupId>com.huluohu.cloud</groupId>
    <version>1.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>

<artifactId>provider-user</artifactId>

<dependencies>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-eureka</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-config</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.retry</groupId>
        <artifactId>spring-retry</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-aop</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-actuator</artifactId>
    </dependency>
</dependencies>

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
            <configuration>
                <finalName>${project.name}</finalName>
            </configuration>
        </plugin>
    </plugins>
</build>

创建启动类

package com.huluohu.cloud.user;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

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

创建配置

bootstrap.yml

spring:
  application:
    name: provider-user
  rabbitmq:
    host: rabbitmq.huluohu.com
    port: 32602
    username: guest
    password: guest
  cloud:
      config:
        uri: http://localhost:8888 # 配置服务器地址
        fail-fast: true # 快速失败
        name: ${spring.application.name} #默认就是spring.application.name
        profile: ${spring.profiles.active:default} # 默认就是spring.profiles.active
        label: master #标签
        retry:
          max-attempts: 6 #最大重试次数
          max-interval: 2000 #间隔时间

application.yml

management:
  security:
    enabled: false

application-local.yml

server:
  port: 9001 #服务端口
eureka:
  instance:
      prefer-ip-address: true
  client:
      register-with-eureka: true
      fetch-registry: true
      service-url:
        defaultZone: http://localhost:8761/eureka/ #eureka server地址

application-local2.yml

server:
  port: 9002 #服务端口
eureka:
  instance:
      prefer-ip-address: true
  client:
      register-with-eureka: true
      fetch-registry: true
      service-url:
        defaultZone: http://localhost:8761/eureka/ #eureka server地址

创建用户查询服务

UserDTO

package com.huluohu.cloud.user.presentation.mode;

import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@Builder
@NoArgsConstructor
@AllArgsConstructor
public class UserDTO {
    private Integer id;
    private String username;
    private String name;
    private Integer age;
    private Long balance;
}

UserController

package com.huluohu.cloud.user.presentation.web;

import com.huluohu.cloud.user.presentation.mode.UserDTO;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

import java.util.Random;

@RestController
public class UserController {
    private Random random = new Random();

    @GetMapping("/{id}")
    public UserDTO findById(@PathVariable Integer id) {
        return UserDTO.builder()
                .id(id)
                .username("root_" + id)
                .name("huluohu_" + id)
                .age(random.nextInt(30) % (30 - 15 + 1) + 15)
                .balance(random.nextLong())
                .build();
    }
}

创建服务消费者

这里以电影服务为例consumer-movie

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">
    <parent>
        <artifactId>huluohu-spring-cloud-demo</artifactId>
        <groupId>com.huluohu.cloud</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>consumer-movie</artifactId>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</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-config</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.retry</groupId>
            <artifactId>spring-retry</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-aop</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <finalName>${project.name}</finalName>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

由于spring-cloud-starter-eureka已经包含了spring-cloud-starter-ribbon的依赖，这里就不用单独添加了。

创建启动类

package com.huluohu.cloud.movie;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

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

创建配置

bootstrap.yml

spring:
  application:
    name: consumer-movie
  rabbitmq:
    host: rabbitmq.huluohu.com
    port: 32602
    username: guest
    password: guest
  cloud:
      config:
        uri: http://localhost:8888 # 配置服务器地址
        fail-fast: true # 快速失败
        name: ${spring.application.name} #默认就是spring.application.name
        profile: ${spring.profiles.active:default} # 默认就是spring.profiles.active
        label: master #标签
        retry:
          max-attempts: 6 #最大重试次数
          max-interval: 2000 #间隔时间

application.yml

management:
  security:
    enabled: false

application-local.yml

server:
  port: 9009
eureka:
  instance:
      prefer-ip-address: true
  client:
      register-with-eureka: true
      fetch-registry: true
      service-url:
        defaultZone: http://localhost:8761/eureka/ #eureka server地址

创建测试代码

配置RestTemplate并启用Ribbon

package com.huluohu.cloud.movie;

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 ApplicationConfiguration {

    @Bean
    @LoadBalanced //启动负载均衡（Ribbon实现）
    public RestTemplate restTemplate(){
        return new RestTemplate();
    }
}

创建服务Facade

package com.huluohu.cloud.movie.application.service;

import com.huluohu.cloud.movie.application.model.User;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;

import javax.annotation.Resource;

@Service
public class UserService {
    @Resource
    private RestTemplate restTemplate;


    public User findById(Integer id) {
        //provider-user为用户服务的服务主机名称，通过该名称从eureka获取服务列表
        return restTemplate.getForObject("http://provider-user/" + id, User.class);
    }
}

创建测试服务

package com.huluohu.cloud.movie.presentation.web;

import com.huluohu.cloud.movie.application.model.User;
import com.huluohu.cloud.movie.application.service.UserService;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.Resource;

@RestController
@RequestMapping("/test")
public class TestController {
    @Resource
    private UserService userService;

    @GetMapping("/user/{id}")
    public Object testFindUser(@PathVariable Integer id){
        final User user = userService.findById(id);
        return ResponseEntity.ok(user);
    }
}

测试

启动Eureka Server(local profile)
启动Config Server(不需要区分profile)
启动provider-user(local profile)
启动provider-user(local2 profile，模拟多节点)
启动consumer-movie(local profile)

启动应用列表

服务注册情况

测试结果

在浏览器中访问http://localhost:9009/test/user/1，访问consumer-movie中的测试接口，结果如下

consumer-movie通过RestTemplate的负载均衡，调用了provide-user的一个节点，并获取数据。

Robbin的简单使用到此介绍完了。

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