Spring Cloud入门教程之服务消费者 Ribbon（二）(Finchley版本+Boot2.0)

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我是靠谱客的博主贪玩网络，最近开发中收集的这篇文章主要介绍Spring Cloud入门教程之服务消费者 Ribbon（二）(Finchley版本+Boot2.0)，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

什么是Ribbon？

Ribbon是一个负载均衡客户端，可以很好的控制htt和tcp的一些行为。Feign默认集成了ribbon。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。

推荐博客：

Ribbon实现服务器端的负载均衡参考博客：https://blog.csdn.net/Jeson0725/article/details/70058910

常见错误：

1、Spring Boot扫描不到controller解决方案加注解指定包路径，多个用逗号隔开

Spring Boot无法自动注入bean问题解决方案：https://blog.csdn.net/zjh_746140129/article/details/80156223

2、Ribbon使用@LoadBalanced报错，由于LoadBalanced是负载均衡，所以使用时不需要指定ip，直接指定服务名

参考博客：https://blog.csdn.net/awhip9/article/details/70599014

一、建立服务消费者

1、项目建立可参考上一篇博客：https://blog.csdn.net/zjh_746140129/article/details/80557302

2、项目pom.xml 新增

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

完整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.serverribbon</groupId>
	<artifactId>serverribbon</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>

	<name>serverribbon</name>
	<description>Demo project for Spring Boot</description>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.0.2.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
		<java.version>1.8</java.version>
		<spring-cloud.version>Finchley.RC2</spring-cloud.version>
	</properties>

	<dependencies>
		<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-ribbon</artifactId>
		</dependency>

		<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>${spring-cloud.version}</version>
				<type>pom</type>
				<scope>import</scope>
			</dependency>
		</dependencies>
	</dependencyManagement>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>

	<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>

3、编写服务消费Service和Controller

通过之前注入ioc容器的restTemplate来消费hello-service服务的“/hi”接口，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

package com.cloud.service;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;

@Service
public class HelloService {

    @Autowired
    RestTemplate restTemplate;

    public String hiService(String name) {
        return restTemplate.getForObject("http://HELLO-SERVICE/hi?name="+name,String.class);
    }
}

package com.cloud.controller;

import com.cloud.service.HelloService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
public class HelloController {

    @Autowired
    HelloService helloService;
    @RequestMapping(value = "/hi")
    @ResponseBody
    public String hi(@RequestParam String name){
        return helloService.hiService(name);
    }
}

4、修改配置文件

server.port=8763
spring.application.name=service-ribbon
#指定服务中心地址
eureka.client.service-url.defaultZone=http://localhost:8761/eureka/

5、修改启动类

在工程的启动类中,通过@EnableDiscoveryClient向服务中心注册；并且向程序的ioc注入一个bean: restTemplate;并通过@LoadBalanced注解表明这个restRemplate开启负载均衡的功能。

package com.serverribbon.serverribbon;

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.context.annotation.ComponentScan;
import org.springframework.web.client.RestTemplate;

@EnableDiscoveryClient
@SpringBootApplication
@ComponentScan("com.cloud.*")
public class ServerribbonApplication {

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


	@Bean
	@LoadBalanced
	RestTemplate restTemplate() {
		return new RestTemplate();
	}
}