Ribbon简介

Ribbon是Netflix发布的负载均衡器，它可以帮我们控制HTTP和TCP客户端的行为。只需为Ribbon配置服务提供者地址列表，Ribbon就可基于负载均衡算法计算出要请求的目标服务地址。

Ribbon默认为我们提供了很多的负载均衡算法，例如轮询、随机、响应时间加权等——当然，为Ribbon自定义负载均衡算法也非常容易，只需实现 IRule 接口即可。

Ribbon入门

新建提供者模块spring-cloud-provider：

pom：

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>com.example</groupId>
        <artifactId>spring-cloud-wsl</artifactId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>
    <groupId>com.example</groupId>
    <artifactId>spring-cloud-provider</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>spring-cloud-provider</name>
    <description>Demo project for Spring Cloud Provider</description>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!-- eureka服务端依赖jar包 -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </dependency>
    </dependencies>
</project>

application.yml配置文件：

server:
  port: 8880
spring:
  application:
    name: provider
#eureka客户端连接配置
eureka:
  client:
    service-url:
      #注册中心地址
      defaultZone: http://localhost:8761/eureka/
  instance:
    #将ip注册到eureka上
    prefer-ip-address: true

controller:

@RestController
public class TestController {
    @Value("${server.port}")
    private String port;

    // 注入配置文件上下文
    @Autowired
    private ConfigurableApplicationContext applicationContext;

    @GetMapping(value = "/test/{name}")
    public String test(@PathVariable String name) {
        return "success! hello: " + name + " i am from port " + port;
    }

    // 从上下文中读取配置
    @GetMapping(value = "/hi")
    public String sayHi() {
        return "Hello " + applicationContext.getEnvironment().getProperty("user.name");
    }
}

启动spring-cloud-provider模块

先启动spring-cloud-eureka，再启动spring-cloud-provider

打开http://localhost:8761/：

红框部分说明已经注册到注册中心

输入http://localhost:8880/test/wangshilin

提供者调用成功

创建消费者模块spring-cloud-consumer-ribbon：

pom：

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>com.example</groupId>
        <artifactId>spring-cloud-wsl</artifactId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>
    <groupId>com.example</groupId>
    <artifactId>spring-cloud-consumer-ribbon</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>spring-cloud-consumer-ribbon</name>
    <description>Demo project for Spring Cloud Consumer Ribbon</description>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!-- eureka客户端依赖jar包 -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
    </dependencies>
</project>

配置文件application.yml：

server:
  port: 8882
spring:
  application:
    name: consumer-ribbon
#eureka客户端连接配置
eureka:
  client:
    service-url:
      #注册中心地址
      defaultZone: http://localhost:8761/eureka/
  instance:
    #将ip注册到eureka上
    prefer-ip-address: true

配置RestTemplate：

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

controller:

@RestController
public class TestController {

    @Autowired
    private RestTemplate restTemplate;

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

    @GetMapping(value = "/test/app/name")
    public String test() {
        return restTemplate.getForObject("http://provider/test/{name}", String.class, appName);
    }
}