在微服務架構中,業務都會被拆分紅一個獨立的服務,服務與服務的通信是基於http restful的。Spring cloud有兩種服務調用方式,一種是ribbon+restTemplate,另外一種是feign。html
Ribbon is a client-side load balancer that gives you a lot of control over the behavior of HTTP and TCP clients. Feign already uses Ribbon, so, if you use @FeignClient, this section also applies.
-- 官方文檔java
ribbon是一個負載均衡客戶端,能夠很好的控制htt和tcp的一些行爲。Feign默認集成了ribbon。web
從新新建一個maven工程,取名爲:service-ribbon;
在它的pom.xml繼承了父pom文件,並引入瞭如下依賴:spring
<?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>sc-f-chapter2</artifactId> <groupId>com.tugohost</groupId> <version>1.0-SNAPSHOT</version> </parent> <modelVersion>4.0.0</modelVersion> <groupId>com.tugohost</groupId> <artifactId>service-ribbon</artifactId> <version>1.0-SNAPSHOT</version> <dependencies> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-netflix-eureka-client</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-netflix-ribbon</artifactId> </dependency> </dependencies> </project>
目錄結構:
apache
在工程的配置文件指定服務的註冊中心地址爲http://localhost:8761/eureka/,程序名稱爲 service-ribbon,程序端口爲8764。配置文件application.yml
以下:瀏覽器
eureka: client: service-url: default-zone: http://localhost:8761/eureka/ server: port: 8764 spring: application: name: service-ribbon
在工程的啓動類中,經過@EnableDiscoveryClient向服務中心註冊;而且向程序的ioc注入一個bean: restTemplate;並經過@LoadBalanced註解代表這個restRemplate開啓負載均衡的功能。restful
/** * @author: Tu9ohost */ @SpringBootApplication @EnableEurekaClient @EnableDiscoveryClient public class ServiceRibbonApplition { public static void main(String[] args) { SpringApplication.run(ServiceRibbonApplition.class,args); } @Bean @LoadBalanced RestTemplate restTemplate(){ return new RestTemplate(); } }
寫一個測試類HelloService,經過以前注入ioc容器的restTemplate來消費service-hi服務的「/hi」接口,在這裏咱們直接用的程序名替代了具體的url地址,在ribbon中它會根據服務名來選擇具體的服務實例,根據服務實例在請求的時候會用具體的url替換掉服務名,代碼以下:架構
/** * @author: Tu9ohost */ @Service public class HelloService { @Autowired RestTemplate restTemplate; public String helloService(String name){ return restTemplate.getForObject("http://SERVICE-HI/hello?name="+name,String.class); } }
寫一個controller,在controller中用調用HelloService 的方法,代碼以下:app
/** * @author: Tu9ohost */ @RestController public class HelloController { @Autowired HelloService helloService; @GetMapping(value = "/hello") public String hello(@RequestParam String name){ return helloService.helloService(name); } }
在瀏覽器上屢次訪問http://localhost:8764/hi?name=forezp,瀏覽器交替顯示:負載均衡
hi forezp,i am from port:8762
hi forezp,i am from port:8763
這說明當咱們經過調用restTemplate.getForObject(「http://SERVICE-HI/hi?name=」+name,String.class)方法時,已經作了負載均衡,訪問了不一樣的端口的服務實例。