【微服务架构】SpringCloud之Feign(五)

蔚落 2022-05-11 05:48 281阅读 0赞

### 【微服务架构】SpringCloud之Feign ###

*   *  Feign简介
     *  声明式REST客户端：Feign
     *  总结

[原文链接][Link 1]

## Feign简介 ##

Feign 是一个声明web服务客户端，这便得编写web服务客户端更容易，使用Feign 创建一个接口并对它进行注解，它具有可插拔的注解支持包括Feign注解与JAX-RS注解，Feign还支持可插拔的编码器与解码器，Spring Cloud 增加了对 Spring MVC的注解，Spring Web 默认使用了HttpMessageConverters, Spring Cloud 集成 Ribbon 和 Eureka 提供的负载均衡的HTTP客户端 Feign.

## 声明式REST客户端：Feign ##

先要启动eureka\_register\_service工程（注册中心）和biz-service-0工程（服务生产者）

创建一个maven工程eureka\_feign\_client  
pom.xml

<parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.4.3.RELEASE</version> <relativePath/>  </parent> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-feign</artifactId> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-eureka</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</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>Brixton.SR5</version> <type>pom</type> <scope>import</scope> </dependency> </dependencies> </dependencyManagement>

在应用主类中通过@EnableFeignClients注解开启Feign功能

启动文件FeignApplication.java

@SpringBootApplication @EnableDiscoveryClient @EnableFeignClients public class FeignApplication { public static void main(String[] args) { SpringApplication.run(FeignApplication.class, args); } }

定义服务接口类UserClient.java

使用@FeignClient(“biz-service-0”)注解来绑定该接口对应biz-service-0服务

@FeignClient("biz-service-0") public interface UserClient { @RequestMapping(method = RequestMethod.GET, value = "/getuser") public User getuserinfo(); @RequestMapping(method = RequestMethod.GET, value = "/getuser") public String getuserinfostr(); @RequestMapping(method = RequestMethod.GET, value = "/info") public String info(); }

在web层中调用上面定义的UserController，具体如下

@RestController public class UserController { @Autowired UserClient userClient; @RequestMapping(value = "/getuserinfo", method = RequestMethod.GET) public User getuserinfo() { return userClient.getuserinfo(); } @RequestMapping(value = "/getuserinfostr", method = RequestMethod.GET) public String getuserinfostr() { return userClient.getuserinfostr(); } @RequestMapping(value = "/info", method = RequestMethod.GET) public String info() { return userClient.info(); } }

application.properties配置变量

spring.application.name=feign-consumer server.port=8004 eureka.client.serviceUrl.defaultZone=http://localhost:8000/eureka/

访问 [http://127.0.0.1:8004/getuserinfo][http_127.0.0.1_8004_getuserinfo]

## 总结 ##

其实通过Feign封装了HTTP调用服务方法，使得客户端像调用本地方法那样直接调用方法，类似Dubbo中暴露远程服务的方式，区别在于Dubbo是基于私有二进制协议，而Feign本质上还是个HTTP客户端

[Link 1]: https://www.cnblogs.com/xiaojunbo/p/7094377.html
[http_127.0.0.1_8004_getuserinfo]: http://127.0.0.1:8004/getuserinfo