創建服務消費者(Ribbon)
概述
在微服務架構中,業務都會被拆分成一個獨立的服務,服務與服務的通訊是基於 http restful 的。Spring cloud 有兩種服務調用方式,一種是 ribbon + restTemplate,另一種是 feign。在這一篇文章首先講解下基於 ribbon + rest。
Ribbon 簡介
Ribbon 是一個負載均衡客戶端,可以很好的控制 http
和 tcp
的一些行爲。
準備工作
- 啓動服務提供者(本教程案例工程爲:
hello-spring-cloud-service-admin
),端口號爲:8762
- 修改配置文件的端口號爲:
8763
,啓動後在 Eureka 中會註冊兩個實例,這相當於一個小集羣
創建服務消費者
創建一個工程名爲 hello-spring-cloud-web-admin-ribbon
的服務消費者項目,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>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
</dependency>
<!-- Spring Cloud End -->
<!-- 解決 thymeleaf 模板引擎一定要執行嚴格的 html5 格式校驗問題 -->
<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 的依賴
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
</dependency>
Application
通過 @EnableDiscoveryClient
註解註冊到服務中心
package com.funtl.hello.spring.cloud.web.admin.ribbon;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
@SpringBootApplication
@EnableDiscoveryClient
public class WebAdminRibbonApplication {
public static void main(String[] args) {
SpringApplication.run(WebAdminRibbonApplication.class, args);
}
}
application.yml
設置程序端口號爲: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,並通過 @LoadBalanced
註解表明開啓負載均衡功能
package com.funtl.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;
@Configuration
public class RestTemplateConfiguration {
@Bean
@LoadBalanced
public RestTemplate restTemplate() {
return new RestTemplate();
}
}
創建測試用的 Service
在這裏我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,代碼如下:
package com.funtl.hello.spring.cloud.web.admin.ribbon.service;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;
@Service
public class AdminService {
@Autowired
private RestTemplate restTemplate;
public String sayHi(String message) {
return restTemplate.getForObject("http://HELLO-SPRING-CLOUD-SERVICE-ADMIN/hi?message=" + message, String.class);
}
}
創建測試用的 Controller
package com.funtl.hello.spring.cloud.web.admin.ribbon.controller;
import com.funtl.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.RequestParam;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class AdminController {
@Autowired
private AdminService adminService;
@RequestMapping(value = "hi", method = RequestMethod.GET)
public String sayHi(@RequestParam String message) {
return adminService.sayHi(message);
}
}
測試訪問
在瀏覽器上多次訪問 http://localhost:8764/hi?message=HelloRibbon
瀏覽器交替顯示:
Hi,your message is :"HelloRibbon" i am from port:8762
Hi,your message is :"HelloRibbon" i am from port:8763
請求成功則表示我們已經成功實現了負載均衡功能來訪問不同端口的實例
此時的架構
- 一個服務註冊中心,Eureka Server,端口號爲:
8761
service-admin
工程運行了兩個實例,端口號分別爲:8762
,8763
web-admin-ribbon
工程端口號爲:8764
web-admin-ribbon
通過RestTemplate
調用service-admin
接口時因爲啓用了負載均衡功能故會輪流調用它的8762
和8763
端口
附
在 IDEA 中配置一個工程啓動多個實例
步驟一
點擊 Run -> Edit Configurations...
步驟二
選擇需要啓動多實例的項目並去掉 Single instance only
前面的勾
步驟三
通過修改 application.yml
配置文件的 server.port
的端口,啓動多個實例,需要多個端口,分別進行啓動即可。