一、场景描述
我们的微服务已经注册到了注册中心，不同的服务之间如何进行调用？这里我们采用feign或者ribbon都可以实现
二、ribbon实现
- Idea-->file-->new-->project-->spring initializr-->next-->修改必要信息-->next
- 分别选择Cloud Routing-->Ribbon
- 再选择 Cloud Discovery-->Eureka Discovery
- 使用ribbon我们需要使用restTemplete，需要web支持，选择Web-->web
- 点击next-->finish
- 查看生成的pom文件如下
<?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.example</groupId>
<artifactId>eurekaribbon</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>eurekaribbon</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.4.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.SR1</spring-cloud.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</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>
</project>
5.我们摘出我们需要的依赖，一个是启用eureka，一个是引入ribbon，一个是引入Web，
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
- application.properties文件中添加eureka配置
spring.application.name=eurekaribbon
server.port=8085
eureka.client.serviceUrl.defaultZone=http://eureka1:8001/eureka/ ,http://eureka1:8002/eureka/,http://eureka1:8003/eureka/
- 启动类添加 @EnableDiscoveryClient
- 启动类中添加restTemplete Bean，完整的启动类如下
package com.example.eurekaribbon;
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;
@SpringBootApplication
@EnableDiscoveryClient
public class EurekaribbonApplication {
@Bean
@LoadBalanced
RestTemplate restTemplate() {
return new RestTemplate();
}
public static void main(String[] args) {
SpringApplication.run(EurekaribbonApplication.class, args);
}
}
- 这样我们就可以基于ribbon来调用其他服务了，重点是restTemplete上面的@LoadBalanced注解
- 我们可以简单写一个调用DEMO的hello服务的实现方式如下：
package com.example.eurekaribbon;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;
import javax.annotation.Resource;
@RestController
public class Hello {
@Resource
RestTemplate restTemplate;
@RequestMapping(value = "/hello")
public String hello(){
return restTemplate.getForObject("http://DEMO/hello",String.class);
}
}
==这里我们引入的RestTemplete是我们在启动类中定义的以@LoadBalanced注解的bean。默认使用的就是ribbon，已经支持负载均衡==
- 我们可以把注册中心，demo服务启动，再启动现有的ribbon服务。调用localhost:8085/hello。得到返回值helloWord
