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Feign是一个声明式的伪Http客户端,它使得写Http客户端变得更简单。使用Feign,只需要创建一个接口并注解。它具有可插拔的注解特性,可使用Feign 注解和JAX-RS注解。Feign支持可插拔的编码器和解码器。Feign默认集成了Ribbon,并和Eureka结合,默认实现了负载均衡的效果。
继续用上一节的工程, 启动eureka-server,端口为8761; 启动service-client 两次,端口分别为8762 、8773.
新建一个spring-boot工程,取名为serice-feign,在它的pom文件引入Feign的起步依赖spring-cloud-starter-feign、Eureka的起步依赖spring-cloud-starter-eureka、Web的起步依赖spring-boot-starter-web,pom.xml文件如下:
4.0.0 org.springframework.boot spring-boot-starter-parent 2.3.2.RELEASE com.itinfo.service-feign service-feign 0.0.1-SNAPSHOT service-feign Demo project for Spring Boot 1.8 Hoxton.SR6 org.springframework.boot spring-boot-starter-web org.springframework.cloud spring-cloud-starter-netflix-eureka-server org.springframework.cloud spring-cloud-starter-openfeign org.springframework.boot spring-boot-starter-test test org.junit.vintage junit-vintage-engine org.springframework.cloud spring-cloud-dependencies ${spring-cloud.version} pom import org.springframework.boot spring-boot-maven-plugin
在工程的配置文件application.yaml文件,指定程序名为service-feign,端口号为8765,服务注册地址为http://localhost:8761/eureka/ ,代码如下:
eureka: client: service-url: defaultZone: http://localhost:8761/eureka/server: port: 8765spring: application: name: service-feign
在程序的启动类ServiceFeignApplication ,加上@EnableFeignClients注解开启Feign的功能:
@SpringBootApplication@EnableDiscoveryClient@EnableFeignClientspublic class ServiceFeignApplication { public static void main(String[] args) { SpringApplication.run(ServiceFeignApplication.class, args); }}
定义一个feign接口,通过@ FeignClient(“服务名”),来指定调用哪个服务。比如在代码中调用了service-client服务的“/hello”接口,代码如下:
@FeignClient(value = "service-hello")public interface SchedualServiceHello { @RequestMapping(value = "/hello",method = RequestMethod.GET) String sayHelloFromClientOne(@RequestParam(value = "name")String name);}
在Web层的controller层,对外暴露一个”/hello”的API接口,通过上面定义的Feign客户端SchedualServiceHello 来消费服务。代码如下:
@RestControllerpublic class HelloController { @Autowired SchedualServiceHello schedualServiceHello; @RequestMapping(value = "/hello",method = RequestMethod.GET) public String sayHello(@RequestParam String name){ return schedualServiceHello.sayHelloFromClientOne(name); }}
启动程序,多次访问http://localhost:8765/hello?name=二哈,浏览器交替显示:
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