SpringCloud(四):服务消费(Feign)

2019-10-30 00:00:00 消费 服务 SpringCloud

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:

《SpringCloud(四):服务消费(Feign)》

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:

《SpringCloud(四):服务消费(Feign)》

 

 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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