SpringCloud-服务的消费者(rest+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,先来说下ribbon+rest
Ribbon简介
Ribbon是一个负载均衡客户端,可以很好的控制http和tcp的一些行为。Feign默认集成了ribbon
实现负载均衡,我们可以通过服务器端和客户端做负载均衡。服务器端做负载均衡,可以使用Nginx。而客户端做负载均衡,就是客户端有一个组件,知道有哪些可用的微服务,实现一个负载均衡算法。
Ribbon工作流程主要分为两步:
第一:先选择Eureka Server,优先选择在同一个Zone且负载较少的Server
第二:再根据用户指定的策略,再从server取到的服务注册列表中选择一个地址。其中Ribbon提供了很多种策略,例如轮询round bin ,随机random,很具响应时间加权
Ribbon已经默认实现了这些配置bean
IClientConfig ribbonClientConfig: DefaultClientConfigImpl
IRule ribbonRule: ZoneAvoidanceRule
IPing ribbonPing: NoOpPing
ServerList ribbonServerList: ConfigurationBasedServerList
ServerListFilter ribbonServerListFilter: ZonePreferenceServerListFilter
ILoadBalancer ribbonLoadBalancer: ZoneAwareLoadBalancer
项目创建
新建一个Eureka Client项目
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.SpringCloud</groupId> <artifactId>service-ribbon</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>service-ribbon</name> <description>service-ribbon-description</description> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.5.13.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>Edgware.SR3</spring-cloud.version> </properties> <dependencies> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-eureka</artifactId> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-ribbon</artifactId> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-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>
application.yml如下
spring: application: name: service-ribbon server: port: 8764 eureka: client: service-url: defaultZone: http://localhost:8761/eureka/
项目启动类修改如下
@EnableDiscoveryClient @SpringBootApplication public class ServiceRibbonApplication { public static void main(String[] args) { SpringApplication.run(ServiceRibbonApplication.class, args); } @Bean @LoadBalanced RestTemplate restTemplate(){ return new RestTemplate(); } }
通过@EurekaDiscoveryClient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。
新建测试service
@Service public class HelloService { @Autowired RestTemplate restTemplate; public String hiService(String name) { return restTemplate.getForObject("http://eureka-client/hello?name=" + name, String.class); } }
新建测试controller
@RestController public class HelloController { @Autowired HelloService helloService; @RequestMapping("/hi") public String hi(@RequestParam String name) { return helloService.hiService(name); } }
浏览器访问
http://localhost:8764/hi?name=test
可看到以下效果