8、服务发现&服务消费者Feign-CFANZ编程社区

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spring cloud的Netflix中提供了两个组件实现软负载均衡调用，分别是Ribbon和Feign。上一篇和大家一起学习了Ribbon。
Ribbon ：Spring Cloud Ribbon是基于HTTP和TCP的客户端负载工具，它是基于Netflix Ribbon实现的，它可以在客户端配置 ribbonServerList（服务端列表），然后轮询请求以实现均衡负载。
Feign ：spring cloud feign 是一个使用起来更加方便的 HTTP 客戶端。在使用ribbon时，通常会使用RestTemplate实现对http请求的封装，形成了模板化的调用方法。spring cloud feign在此基础上做了进一步的封装，Feign是一种声明式、模板化的HTTP客户端。在Spring Cloud中使用Feign, 可以做到使用HTTP请求远程服务时能与调用本地方法一样的编码体验，完全感知不到这是远程方法，更感知不到这是个HTTP请求。

1、新建项目sc-eureka-client-consumer-feign，对应的pom.xml文件如下

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>

	<groupId>spring-cloud</groupId>
	<artifactId>sc-eureka-client-consumer-feign</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>

	<name>sc-eureka-client-consumer-feign</name>
	<url>http://maven.apache.org</url>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.0.4.RELEASE</version>
	</parent>

	<dependencyManagement>
		<dependencies>
			<dependency>
				<groupId>org.springframework.cloud</groupId>
				<artifactId>spring-cloud-dependencies</artifactId>
				<version>Finchley.RELEASE</version>
				<type>pom</type>
				<scope>import</scope>
			</dependency>

		</dependencies>
	</dependencyManagement>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<maven.compiler.source>1.8</maven.compiler.source>
		<maven.compiler.target>1.8</maven.compiler.target>
	</properties>

	<dependencies>
	
		<!-- 说明是一个 eureka client -->
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
		</dependency>

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>
		
		<!-- <dependency> 
		        <groupId>org.springframework.cloud</groupId> 
		        <artifactId>spring-cloud-starter-feign</artifactId> 
			    <version>1.4.5.RELEASE</version> 
		   </dependency> -->

		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-openfeign</artifactId>
		</dependency>
		
	</dependencies>
</project>

备注：spring cloud 2.x后spring-cloud-starter-feign已经被标识为过期，推荐使用spring-cloud-starter-openfeign

8、服务发现&服务消费者Feign_springboot

2、新建spring boot启动类ConsumerFeignApplication.java

package sc.consumer;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.openfeign.EnableFeignClients;

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

}

3、创建配置文件bootstrap.yml和application.yml，对应的内容如下

bootstrap.yml

server:
  port: 5800


application.yml

spring:
  application:
    name: sc-eureka-client-consumer-feign

eureka:
  client:
    registerWithEureka: true #是否将自己注册到Eureka服务中，默认为true
    fetchRegistry: true #是否从Eureka中获取注册信息，默认为true
    serviceUrl:
      defaultZone: http://localhost:5001/eureka/

4、编写feign客户端

package sc.consumer.service;

import java.util.Map;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;

import sc.consumer.model.User;

@FeignClient(value="sc-eureka-client-provider")
public interface UserService {

	@GetMapping("/user/getUser/{id}")
	Map<String, Object> getUser(@PathVariable(value ="id") Long id);

	@RequestMapping("/user/listUser")
	Map<String, Object> listUser();

	@PostMapping("/user/addUser")
	Map<String, Object> addUser(@RequestBody User user);

	@PutMapping("/user/updateUser")
	Map<String, Object> updateUser(@RequestBody User user);

	@DeleteMapping("/user/deleteUser/{id}")
	Map<String, Object> deleteUser(@PathVariable(value ="id") Long id);

}

5、分别启动注册中心项目sc-eureka-server和服务提供者sc-eureka-client-provider

6、启动项目sc-eureka-client-consumer-feign，并验证是否启动成功

方法一

8、服务发现&服务消费者Feign_springcloud_02