SpringCloud（4）-通过Ribbon/Feign两种方式请求服务

服务的消费者

在上一个博客中，已经讲述了如何搭建一个服务提供者，并注册到eureka注册中心去。在这一博客，主要介绍，如何请求提供的服务。我们有两种方式去请求别人提供的服务，ribbon+RestTemplate或者Feign这两种方式请求

使用Ribbon+restTemplate请求

1. 在pom.xml文件中引入依赖

   <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>
   

2. application.properties配置文件的配置

   server.port=85
   spring.application.name=consume
   eureka.client.service-url.defaultZone=http://master:81/eureka/
   

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

4. 配置RestTemplate

   import org.springframework.cloud.client.loadbalancer.LoadBalanced;
   import org.springframework.context.annotation.Bean;
   import org.springframework.context.annotation.Configuration;
   import org.springframework.web.client.RestTemplate;
   
   @Configuration
   public class config {
       //@LoadBalanced 负载均衡
       @Bean
       @LoadBalanced
       RestTemplate restTemplate(){
           return new RestTemplate();
       }
   }
   

5. service层使用restTemplate来请求

   import org.springframework.beans.factory.annotation.Autowired;
   import org.springframework.stereotype.Service;
   import org.springframework.web.client.RestTemplate;
   
   @Service
   public class ConsumeService {
       @Autowired
       private RestTemplate restTemplate;
       public String consumeHello(){
           //provider 是你提供者的spring.application.name的值
           return restTemplate.getForObject("http://provider?name=test",String.class);
       }
   }
   

使用Feign来请求

1. 使用fegion的方式来请求，使请求变得更简单，只需要定义一个接口，在接口上面注解FeignClient

   import org.springframework.cloud.openfeign.FeignClient;
   import org.springframework.web.bind.annotation.RequestMapping;
   import org.springframework.web.bind.annotation.RequestMethod;
   import org.springframework.web.bind.annotation.RequestParam;
   
   @FeignClient(value = "provider")
   public interface FegionService {
   
       @RequestMapping(method = RequestMethod.GET)
        String feignHello(@RequestParam(value = "name") String name);
   }
   

2. 在启动类上注解

   @EnableFeignClients