SpringCloud之Feign示例详解

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/> <!-- lookup parent from repository --></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@EnableFeignClientspublic 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

@RestControllerpublic 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-consumerserver.port=8004eureka.client.serviceUrl.defaultZone=http://localhost:8000/eureka/ 

访问 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

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持武林网。