负载均衡---ribbon

作者: dalaoyang | 来源:发表于2018-04-19 16:33 被阅读147次

Ribbon:提供云端负载均衡，有多种负载均衡策略可供选择，可配合服务发现和断路器使用。

上一篇简单讲解了eureka的使用，这一篇文章基于上一篇的基础上，讲一下springcloud的另一个重要的组件ribbon。

这篇文章需要新建三个工程，service（8762），service（8763），service-ribbon（8764），三个服务分别向eureka-server注册中心注册，本文的服务使用的注册中心都是本人创建的测试eureka--http://eureka.dalaoyang.cn。

首先新建一个service（8762），括号内的8762是项目的端口号，加入eureka依赖，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.dalaoyang</groupId>
    <artifactId>springcloud_service</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>springcloud_service</name>
    <description>springcloud_service</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.9.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.SR1</spring-cloud.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</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>

配置文件

##端口号
server.port=8762

##服务名称
spring.application.name=service

##注册中心地址
eureka.client.service-url.defaultZone=http://eureka.dalaoyang.cn/eureka/

启动类使用注解@EnableEurekaClient向注册中心注册，代码如下：

package com.dalaoyang;

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.RestController;

@SpringBootApplication
@RestController
@EnableEurekaClient
public class SpringcloudServiceApplication {

    public static void main(String[] args) {
        SpringApplication.run(SpringcloudServiceApplication.class, args);
    }


    @Value("${server.port}")
    String port;

    @Value("${spring.application.name}")
    String serviceName;

    @GetMapping("/")
    public String index(){
        return "serviceName=" + serviceName + "-------port=" + port;
    }
}

到这里service（8762）创建完成，然后复制一个项目，端口号改为8763作为service（8763）。

然后新建项目service-ribbon（8764），pom文件加入ribbon依赖，pom完整代码如下：

<?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.dalaoyang</groupId>
    <artifactId>springcloud_ribbon</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>springcloud_ribbon</name>
    <description>springcloud_ribbon</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.9.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.SR1</spring-cloud.version>
    </properties>

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

            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-ribbon</artifactId>
        </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>

配置文件如下：

##端口号
server.port=8764

##服务名称
spring.application.name=service_ribbon

##注册中心地址
eureka.client.service-url.defaultZone=http://eureka.dalaoyang.cn/eureka/

由于只是一个简单demo，所有我将java代码都写在了启动类里面，解释一下，@LoadBalanced放在RestTemplate上面，表明RestTemplate开启负载均衡。代码如下：

package com.dalaoyang;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.context.annotation.Bean;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication
@EnableEurekaClient
@RestController
public class SpringcloudRibbonApplication {

    public static void main(String[] args) {
        SpringApplication.run(SpringcloudRibbonApplication.class, args);
    }

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

    @Value("${server.port}")
    String port;

    @Value("${spring.application.name}")
    String serviceName;

    @GetMapping("/")
    public String index(){
        return restTemplate().getForObject("http://service/",String.class);
    }
}

分别启动service（8762），service（8763），service-ribbon（8764）三个工程。
先查看http://eureka.dalaoyang.cn/,可以看到三个实例注册成功。如下图：