微服務(wù)調(diào)用方式

微服務(wù)調(diào)用方式之Ribbon

Ribbon簡(jiǎn)介

Ribbon是Netflix發(fā)布的云中間層服務(wù)開源項(xiàng)目，其主要功能是提供客戶端實(shí)現(xiàn)負(fù)載均衡算法。Ribbon客戶端組件提供一系列完善的配置項(xiàng)如連接超時(shí)，重試等葵袭。簡(jiǎn)單的說(shuō)沉颂，Ribbon是一個(gè)客戶端負(fù)載均衡器，我們可以在配置文件中Load Balancer后面的所有機(jī)器独泞，Ribbon會(huì)自動(dòng)的幫助你基于某種規(guī)則（如簡(jiǎn)單輪詢，隨機(jī)連接等）去連接這些機(jī)器苔埋，我們也很容易使用Ribbon實(shí)現(xiàn)自定義的負(fù)載均衡算法懦砂。

Ribbon的使用

通過(guò)IDEA創(chuàng)建項(xiàng)目并引入依賴

<?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>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.4.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.yuan</groupId>
    <artifactId>order_service</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>order_service</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Greenwich.SR1</spring-cloud.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <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-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>

向注冊(cè)中心注冊(cè)服務(wù)(application.yml)

server:
  port: 8781

#指定注冊(cè)中心地址
eureka:
  client:
    service-url:
      defaultZone: http://localhost:8761/eureka/

#服務(wù)的名稱
spring:
  application:
    name: order-service

使用Ribbon
啟動(dòng)類中加入如下代碼:

    @Bean
    @LoadBalanced
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }

使用添加@LoadBalanced注解后的RestTemplate調(diào)用服務(wù)提供者的接口時(shí)，可以使用虛擬IP替代真實(shí)IP地址组橄。所謂的虛擬IP就是服務(wù)提供者在application.yml文件中配置的spring.application.name屬性的值荞膘。示例如下：（調(diào)用上篇文章中的）

@RestController
@RequestMapping("api/v1/order")
public class OrderController {

    @Autowired
    private RestTemplate restTemplate;

   //調(diào)用方式二
   @Autowired
   private LoadBalancerClient loadBalancer;

    @RequestMapping("save")
    public Object save(@RequestParam("user_id") int userId,@RequestParam("product_id") int productId){
        Object obj=restTemplate.getForObject("http://product-service/api/v1/product/findById?id="+productId,Object.class);

         //調(diào)用方式二
        //ServiceInstance instance = loadBalancer.choose("product-service");
         //String url = String.format("http://%s:%s/api/v1/product/find?id="+productId, instance.getHost(),instance.getPort());
        // RestTemplate restTemplate = new RestTemplate();
        // Map<String,Object> productMap = restTemplate.getForObject(url, Map.class);

       return obj;

    }
}

啟動(dòng)注冊(cè)中心服務(wù)提供者和消費(fèi)者

調(diào)用url進(jìn)行測(cè)試

可以發(fā)現(xiàn)有負(fù)載均衡默認(rèn)調(diào)用為輪詢每個(gè)端口被輪著調(diào)用

修改負(fù)載均衡策略(IRule實(shí)現(xiàn)類全路徑)
文檔：http://cloud.spring.io/spring-cloud-static/Finchley.RELEASE/single/spring-cloud.html#_customizing_the_ribbon_client_by_setting_properties

#自定義負(fù)載均衡策略
product-service:
  ribbon:
    NFLoadBalancerRuleClassName: com.netflix.loadbalancer.RandomRule

如果部分機(jī)器配置強(qiáng)，則可以改為 WeightedResponseTimeRule