簡介
RestTemplate
Spring用於同步client端的核心類,簡化了與http服務的通信,並滿足RESTful原則,程序代碼可以給它提供URL,並提取結果。默認情況下,RestTemplate默認依賴jdk的HTTP連接工具。
Ribbon
Spring Cloud Ribbon是一個基於HTTP和TCP的客戶端負載均衡工具,它基於Netflix Ribbon實現。通過Spring Cloud的封裝,可以讓我們輕鬆地將面向服務的REST模版請求自動轉換成客戶端負載均衡的服務調用。Spring Cloud Ribbon幾乎存在於每一個Spring Cloud構建的微服務和基礎設施中。因爲微服務間的調用,API網關的請求轉發等內容,實際上都是通過Ribbon來實現的,包括Feign,它也是基於Ribbon實現的工具。
在Spring Cloud中,當Ribbon與Eureka配合使用時,Ribbon可自動從Eureka Server獲取服務提供者地址列表,並基於負載均衡算法,選擇其中一個服務提供者實例。
啓動註冊中心和服務提供者
https://blog.csdn.net/miaodichiyou/article/details/104160284
1、啓動SpringCloud高可用服務註冊中心(Eureka)搭建的註冊中心
2、在springcloud-eureka-provider項目Hi_provider.java文件中添加一個controller,對外提供服務 "/hi"
package org.springcloud.eureka.provider;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
@SpringBootApplication
@EnableEurekaClient
public class Hi_provider
{
public static void main( String[] args )
{
SpringApplication.run(Hi_provider.class, args);
}
@RestController
public class HiController {
@Value("${server.port}")
String port;
@GetMapping("/hi")
public String Home(@RequestParam String name){
return "hi "+name+",This is from serverport:"+port;
}
}
}
啓動三個springcloud-eureka-provider實例,端口分別爲8001,8002和8003
創建服務消費者
添加依賴包文件POM.xml
<?xml version="1.0"?>
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.springcloud</groupId>
<artifactId>springcloud-root</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<artifactId>springcloud-ribbon</artifactId>
<name>springcloud-ribbon</name>
<url>http://maven.apache.org</url>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</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.apache.httpcomponents</groupId>
<artifactId>httpclient</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>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-configuration-processor</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
配置application.yml文件
spring:
application:
name: springcloud-ribbon
freemarker:
prefer-file-system-access: false
security:
user:
name: admin
password: 123456
server:
port: 8100
eureka:
instance:
hostname: eureka-ribbon.com
instance-id: eureka-ribbon
client:
service-url:
defaultZone: http://${spring.security.user.name}:${spring.security.user.password}@eureka-peer1.com:8897/eureka/,http://${spring.security.user.name}:${spring.security.user.password}@eureka-peer2.com:8898/eureka/,http://${spring.security.user.name}:${spring.security.user.password}@eureka-peer3.com:8899/eureka/
修改C:\Windows\System32\drivers\etc\hosts
127.0.0.1 eureka-ribbon.com
添加服務消費者啓動類
- RibbonApplication.java
package org.springcloud.ribbon;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class RibbonApplication {
public static void main(String[] args) {
SpringApplication.run(RibbonApplication.class, args);
}
}
添加RESTful API接口
調用springcloud-eureka-provider實例的API接口"/hi",即消費服務。由於springcloud-eureka-provider爲三個實例(端口8001、8002、8003),在調用時希望做到輪流訪問這三個實例,這時需要將RestTemplate和Ribbon結合進行負載均衡。只需要在程序的IOC容器中注入一個restTemplate的Bean,並加上@LoadBalanced註解,此時RestTemplate就結合了Ribbon開啓了負載均衡功能。
- RestTemplateConfig.java
package org.springcloud.ribbon;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.client.HttpComponentsClientHttpRequestFactory;
import org.springframework.web.client.RestTemplate;
@Configuration
public class RestTemplateConfig {
@Bean
@LoadBalanced
public RestTemplate restTemplate(){
HttpComponentsClientHttpRequestFactory httpRequestFactory = new HttpComponentsClientHttpRequestFactory();
httpRequestFactory.setConnectionRequestTimeout(30000);
httpRequestFactory.setConnectTimeout(30000);
httpRequestFactory.setReadTimeout(30000);
return new RestTemplate(httpRequestFactory);
}
}
添加service消費服務提供者實例提供的服務
編寫一個RibbonService類,在該類的hi()方法用restTemplate調用springcloud-eureka-provider的API接口,uri上不需要使用硬編碼(如IP地址),只需寫服務名springcloud-eureka-provider即可。
- RibbonService.java
package org.springcloud.ribbon;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;
@Service
public class RibbonService {
@Autowired
RestTemplate restTemplate;
public String hi(String name){
return restTemplate.getForObject("http://springcloud-eureka-provider/hi?name="+name,String.class);
}
}
注:getForObject中的url springcloud-eureka-provider爲springcloud-eureka-provider項目(服務提供者)的應用名稱,也就是在創建springcloud-eureka-provider項目時在配置文件中配置的spring.application.name=springcloud-eureka-provider。hi爲springcloud-eureka-provider項目中接口的地址(controller), name是請求參數。
創建controller,調用service中的方法
編寫一個RibbonController類
package org.springcloud.ribbon;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class RibbonController {
@Autowired
private RibbonService ribbonService;
@GetMapping("/hi")
public String hi(@RequestParam(required = false,defaultValue = "zhaojq") String name){
return ribbonService.hi(name);
}
}
啓動springcloud-ribbon工程
查看Eureka註冊中心
運行啓動類,訪問http://eureka-peer1.com:8897/
http://eureka-peer2.com:8898/,http://eureka-peer3.com:8899/ 結果同上。
服務消費者實例已成功註冊。
在瀏覽器地址欄訪問ribbon項目中的controller
在瀏覽器多次訪問http://localhost:8100/hi?name=zhaojq,瀏覽器會輪流顯示如下
當一直刷新http://localhost:8100/hi?name=zhaojq時可以發現瀏覽器交替顯示端口8001,8002和8003,說明已經實現客戶端的負載均衡,並且Ribbon默認採用輪詢的負載均衡算法。
Ribbon負載均衡策略
自定義負載均衡策略(隨機策略)
修改springcloud-ribbon工程的application.yml配置文件添加如下配置:
# 自定義配置負載均衡策略
Load_Balance:
ribbon:
NFLoadBalancerRuleClassName: com.netflix.loadbalancer.RandomRule
Load_Balance爲需要負載的服務地址,com.netflix.loadbalancer.RandomRule爲服務策略。此處我們配置爲隨機策略
修改RestTemplateConfig配置類:
@Bean
public IRule ribbonRule() {
return new RandomRule();//實例化與配置文件對應的策略類
}
修改RibbonController
package org.springcloud.ribbon;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.loadbalancer.LoadBalancerClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class RibbonController {
@Autowired
private RibbonService ribbonService;
@Autowired
private LoadBalancerClient loadBalancerClient;
@GetMapping("/hi")
public String hi(@RequestParam(required = false,defaultValue = "zhaojq")String name){
this.loadBalancerClient.choose("Load_Balance");
return ribbonService.hi(name);
}
}
LoadBalancerClient(RibbonLoadBalancerClient是實現類)在初始化的時候(execute方法),會通過ILoadBalance(BaseLoadBalancer是實現類)向Eureka註冊中心獲取服務註冊列表,並且每10s一次向EurekaClient發送“ping”,來判斷服務的可用性,如果服務的可用性發生了改變或者服務數量和之前的不一致,則從註冊中心更新或者重新拉取。LoadBalancerClient有了這些服務註冊列表,就可以根據具體的IRule來進行負載均衡。
重新啓動springcloud-ribbon項目,訪問http://eureka-ribbon.com:8100/hi?name=zhaojq
在命令窗口curl http://eureka-ribbon.com:8100/hi,發現Ribbon已經實現隨機負載均衡策略