SpringCloudNetflix(5)服务消费者(Ribbon)

2020-04-08

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。在这一篇文章首先讲解下基于 ribbon +
rest。

Ribbon 简介

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

准备工作

  1. 启动服务提供者(本案例工程为:hello-spring-cloud-service-admin),端口号为:8762
  2. 按照步骤去掉勾选,可以多次运行
    image.png
    image.png
  3. 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
    image.png

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.funtl</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>
    <url>http://www.funtl.com</url>
    <inceptionYear>2018-Now</inceptionYear>

    <dependencies>
        <!-- Spring Boot Begin -->
        <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>
        <!-- Spring Boot End -->

        <!-- Spring Cloud Begin -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </dependency>
        <!--服务的消费者-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
        </dependency>
        <!-- Spring Cloud End -->

        <!-- 解决 thymeleaf 模板引擎一定要执行严格的 html5 格式校验问题 -->
        <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.funtl.hello.spring.cloud.web.admin.ribbon.WebAdminRibbonApplication</mainClass>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

主要是增加了 Ribbon 的依赖

<!--服务的消费者-->
        <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.misterzhang.top.hello.spring.cloud.web.admin.ribbon;

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

/**
 * @author zhangfan
 * @date 2020/4/8
 */
@SpringBootApplication
@EnableDiscoveryClient          //通过注解,注册到服务中心
public class WebAdminRibbonApplication {

    public static void main(String[] args) {
        SpringApplication.run(WebAdminRibbonApplication.class,args);
    }
}

application.yml ,设置程序端口号为:8764

spring:
  application:
    name: hello-spring-cloud-web-admin-ribbon
  thymeleaf:
    cache: false
    mode: LEGACYHTML5
    encoding: UTF-8
    servlet:
      content-type: text/html

server:
  port: 8764

eureka:
  client:
    serviceUrl:
      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.misterzhang.top.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;

/**
 * @author zhangfan
 * @date 2020/4/8
 */
@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.misterzhang.top.hello.spring.cloud.web.admin.ribbon.service;

/**
 * @author zhangfan
 * @date 2020/4/8
 */
public interface AdminService {

    String sayHi(String message);
}

package com.misterzhang.top.hello.spring.cloud.web.admin.ribbon.service.impl;

import com.misterzhang.top.hello.spring.cloud.web.admin.ribbon.service.AdminService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;

/**
 * @author zhangfan
 * @date 2020/4/8
 */
@Service
public class AdminServiceImpl implements AdminService {

    @Autowired
    private RestTemplate restTemplate;


    @Override
    public String sayHi(String message) {
        //url为运行程序的名字拼接网址
        return restTemplate.getForObject("http://hello-spring-cloud-service-admin/hi?message=" + message, String.class);
    }
}

创建测试用的 Controller

package com.misterzhang.top.hello.spring.cloud.web.admin.ribbon.controller;

import com.misterzhang.top.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.RestController;

/**
 * @author zhangfan
 * @date 2020/4/8
 */
@RestController
public class AdminController {

    @Autowired
    private AdminService adminService;

    @RequestMapping(value = "hi",method = RequestMethod.GET)
    public String sayHi(String message){
        return adminService.sayHi(message);
    }
}

测试访问

在浏览器上多次访问 http://localhost:8764/hi?message=HelloRibbon
浏览器交替显示:

Hi,your message is :"HelloRibbon" i am from port:8762
Hi,your message is :"HelloRibbon" i am from port:8763
请求成功则表示我们已经成功实现了负载均衡功能来访问不同端口的实例

此时的架构

Lusifer201805292246004.png

  1. 一个服务注册中心,Eureka Server,端口号为:8761
  2. service-admin 工程运行了两个实例,端口号分别为:87628763
  3. web-admin-ribbon 工程端口号为:8764
  4. web-admin-ribbon 通过 RestTemplate 调用 service-admin 接口时因为启用了负载均衡功能故会轮流调用它的 87628763 端口

标题:SpringCloudNetflix(5)服务消费者(Ribbon)
作者:张范
地址:http://misterzhang.top/articles/2020/04/08/1586357264596.html