创建服务消费者(Feign)

概述

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

• Feign 采用的是基于接口的注解

• Feign 整合了 ribbon和hystrix

创建服务消费者

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</artifactId>
        </dependency>
​
        <!--spring cloud starter feign-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-feign</artifactId>
        </dependency>
​
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
​

主要增加对Feign的依赖

Application

通过@EnableFeignClients注解开启Feign功能

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

application.yml

server:
  port: 9002
​
eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:1111/eureka/
  instance:
    lease-renewal-interval-in-seconds: 10 #服务续约
    lease-expiration-duration-in-seconds: 15 #服务剔除>服务续约时间
    hostname: localhost
    instance-id: ${eureka.instance.hostname}:${spring.application.name}:${server.port}
spring:
  application:
    name: eureka-client-feign
feign:
  client:
    config:
      eureka-provider:
        #配置feign日志级别
        logger-level: full
  #开启feign对hystrix的支持,默认为false
  hystrix:
    enabled: true
logging:
  level:
    #必须设置feign的服务包日志级别为debug
    com.ley.springcloud.feign.service: debug

创建Feign接口

通过@FeignClient("服务名")注解来指定调用哪个服务

import org.springframework.cloud.netflix.feign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
​
@FeignClient(name = "eureka-provider")
public interface HelloService {
​
    @GetMapping("/hello")
    String hello();
}
​

创建测试用的Controller

import com.ley.springcloud.feign.service.HelloService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
​
@RestController
@RequestMapping("/api")
public class FeignController {
​
    @Autowired
    private HelloService helloService;
​
    @GetMapping("/feign/hello")
    public String hello() {
        return helloService.hello();
    }
}