SpringCloud(四):服务消费(Feign)
一、Feign介绍
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。
二、Feign消费者服务:
pom.xml:
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-feign</artifactId>
</dependency>
application.properties:
spring.application.name=hello-consumer-feign server.port=8031 eureka.client.serviceUrl.defaultZone=http://localhost:8001/eureka/
Feign客户端:package cn.demo.service;
import org.springframework.cloud.netflix.feign.FeignClient; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestParam;
//注意点:这里user-service大小写都可以,默认会转成大写 @FeignClient("user-service") public interface HelloService {
//这里必须是这样配置,如果不配置或者配置的value=name1或者是其他值,相当于传其他参数key过去,在这里传错的话,会返回hello, null,因为hello-service接口拿不到name的值。 @RequestMapping("hello") String hello (@RequestParam(value = "name") String name) ;
}
启动类:
package cn.demo; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.cloud.client.discovery.EnableDiscoveryClient; import org.springframework.cloud.netflix.feign.EnableFeignClients; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; import cn.demo.service.HelloService; @SpringBootApplication @EnableDiscoveryClient @EnableFeignClients @RestController public class HelloConsumerFeignApplication { public static void main(String[] args) { SpringApplication.run(HelloConsumerFeignApplication.class, args); } @Autowired private HelloService helloService; @RequestMapping("hello") public String hello(String name){ return helloService.hello(name); } }
三、测试
同样的,先启动eureka-server:8001, 以及hello-service:8011,8012,然后访问:
http://localhost:8031/hello?name=feign
结果:
同样的多次访问,hello-service:8011,8012日志都有打印调用信息,表示也实现了负载均衡。
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