Spring Cloud實戰(四)-Spring Cloud Netflix Feign

概要

• 什麼是Spring Cloud Netflix Feign?

• 怎麼用Feign?

什麼是Spring Cloud Netflix Feign?

Feign:Declarative REST clients.
Feign:是一個聲明式的REST客戶端.
在之前的例子中我們使用的有DiscoveryClient,LoadBalancerClient,如他們一樣FeignClient也是調用Eureka Server中服務用的,不過它提供了聲明式的REST風格的調用,使編程更加簡單.它是在運行時Runtime實現接口的實現,所以pom可以指定運行時依賴.

怎麼用Feign?

百說不如一run,構造一個例子來實現

• Eureka Server 如之前一樣,正常啓動即可

• Eureka-Client 修改bootstrap.xml,變得簡單一點,只有noun服務

spring:
  application:
    name: noun
server:
  port: 8030
eureka:
  client:
    service-url:
      defaultZone: http://127.0.0.1:8010/eureka/

• Sentence-Client添加NounClient接口

@FeignClient("noun")
public interface NounClient {

    @RequestMapping(value = "/",method = RequestMethod.GET)
    public  String getWord();
}

• Sentence-Client添加pom.xml

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

• Sentence-Client在Application添加@EnableFeignClients

• Sentence-Client在SentenceController中使用NounClient

@RestController
public class SentenceController {

    @Autowired
    private NounClient nounClient;
    @RequestMapping("/sentence")
    public @ResponseBody
    String getSentence() {
        return
                "<h3>造句:</h3><br/>" +
                        buildSentence() + "<br/><br/>" +
                        buildSentence() + "<br/><br/>" +
                        buildSentence() + "<br/><br/>" +
                        buildSentence() + "<br/><br/>" +
                        buildSentence() + "<br/><br/>"
                ;
    }
    public String buildSentence() {
        String sentence = "There was a problem assembling the sentence!";
        try{
            sentence =  nounClient.getWord();
        } catch ( Exception e ) {
            System.out.println(e);
        }
        return sentence;
    }

}

• 現在去http://127.0.0.1:8080/sentence檢查下是否調用服務成功吧

特別感謝 kennyk65
Spring Cloud 中文用戶組 31777218
Spring-Cloud-Config 官方文檔-中文譯本 (本人有參與,哈哈)
Spring Cloud Netflix 官網文檔-中文譯本
本文實例github地址 mmb-feign

原文地址：https://segmentfault.com/a/1190000006188802