Ribbon【入门】

公共依赖：

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.3.RELEASE</version>
        <relativePath/>
</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>Finchley.RELEASE</spring-cloud.version>
</properties>

<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>

1、创建eureka-server注册中心工程

a、eureka-server工程pom依赖：

<!--加上上面的公共依赖-->

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

<build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
</build>

b、eureka-server启动类：

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;

@SpringBootApplication
@EnableEurekaServer
public class EurekaServerApplication {

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

c、eureka-server工程配置文件：eureka-server\src\main\resources\bootstrap.yml

server:
  port: 8888
eureka:
  instance:
    hostname: localhost
  client:
    registerWithEureka: false
    fetchRegistry: false
    serviceUrl:
      defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/

d、启动注册中心

mvn spring-boot:run

2、创建demo-client服务工程

a、demo-client工程pom配置：

<!--加上上面的公共依赖-->

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

<build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
</build>

b、demo-client启动类：

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

@SpringBootApplication
@EnableDiscoveryClient
public class ClientApplication {

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

c、demo-client工程配置文件：demo-client\src\main\resources\bootstrap.yml

server:
  port: 7070
spring:
  application:
    name: client
eureka:
  client:
    serviceUrl:
      defaultZone: http://${eureka.host:127.0.0.1}:${eureka.port:8888}/eureka/
  instance:
    prefer-ip-address: true

d、编写测试接口：

import javax.servlet.http.HttpServletRequest;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * 测试API
 */
@RestController
public class TestController {

    @GetMapping("/testApi")
    public String testApi(Integer a, Integer b, HttpServletRequest request) {
        return " From Port: " + request.getServerPort() + ", Result: " + (a + b);
    }
}

e、启动工程

mvn spring-boot:run

mvn spring-boot:run -Dserver.port=7171

启动了2个工程实例，一个端口是7070，一个是7171

3、创建demo-ribbon客户端工程

a、demo-ribbon工程pom依赖：

<!--加上上面的公共依赖-->

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

<build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
</build>

b、demo-ribbon工程启动类：

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication
@EnableDiscoveryClient
public class RibbonLoadbalancerApplication {

    public static void main(String[] args) {
        SpringApplication.run(RibbonLoadbalancerApplication.class, args);
    }
    
　　 //声明该RestTemplate用于负载均衡
    @Bean
    @LoadBalanced
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }
}

c、编写一个测试接口：

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

@RestController
public class TestController {

    @Autowired
    private RestTemplate restTemplate;

    @GetMapping("/testApi")
    public String testApi(Integer a, Integer b) {
　　　　 //使用RestTemplate调用demo-client工程暴露的测试API接口
        String result = restTemplate.getForObject("http://CLIENT/testApi?a=" + a + "&b=" + b, String.class);
        System.out.println(result);
        return result;
    }
}

d、demo-ribbon工程配置文件：demo-ribbon\src\main\resources\bootstrap.yml

spring:
  application:
    name: ribbon-loadbalancer
server:
  port: 7777
eureka:
  client:
    serviceUrl:
      defaultZone: http://${eureka.host:127.0.0.1}:${eureka.port:8888}/eureka/
  instance:
    prefer-ip-address: true

e、启动demo-ribbon工程：

mvn spring-boot:run

4、访问 localhost:7777/testApi?a=2019&=2020

从结果可以看到这次访问的是7171端口服务。

从下面的控制台输出可以看出，ribbon在做负载均衡的时候，默认使用的是轮询的方式！

入门成功！！！