SpringCloud之负载均衡Feign

1. 说明

   Feign通过接口的方法调用Rest服务，之前是Ribbon+ResuTemplete,该请求发生给Eureka服务器，通过Feign直接找到服务接口，由于在进行服务调用的时候融合了Ribbon技术，所以也支持负载均衡，实现方式是接口[email protected]注解的形式

2. 案例

   （1）pom文件

<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>
	<parent>
		<groupId>com.atguigu.springcloud</groupId>
		<artifactId>microservicecloud</artifactId>
		<version>0.0.1-SNAPSHOT</version>
	</parent>

	<artifactId>microservicecloud-consumer-dept-feign</artifactId>


	<dependencies>
		<dependency><!-- 自己定义的api -->
			<groupId>com.atguigu.springcloud</groupId>
			<artifactId>microservicecloud-api</artifactId>
			<version>${project.version}</version>
		</dependency>
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-feign</artifactId>
		</dependency>
		<!-- Ribbon相关 -->
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-eureka</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-ribbon</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-config</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>
		<!-- 修改后立即生效，热部署 -->
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>springloaded</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-devtools</artifactId>
		</dependency>
	</dependencies>
</project>
           

（2）yaml配置文件

server:
  port: 80
  
eureka:
  client:
    register-with-eureka: false
    service-url: 
      defaultZone: http://eureka7001.com:7001/eureka/,http://eureka7002.com:7002/eureka/,http://eureka7003.com:7003/eureka/  
           

（3）主启动类

添加@EnableFeignClients(basePackages= {“com.atguigu.springcloud”})开启Feign

package com.atguigu.springcloud;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.netflix.feign.EnableFeignClients;
import org.springframework.context.annotation.ComponentScan;

@SpringBootApplication
@EnableEurekaClient
@EnableFeignClients(basePackages= {"com.atguigu.springcloud"})
@ComponentScan("com.atguigu.springcloud")
public class DeptConsumer80_Feign_App
{
	public static void main(String[] args)
	{
		SpringApplication.run(DeptConsumer80_Feign_App.class, args);
	}
}
           

（4）Feign的实现（核心）

一般是放在公共部分用于其他服务进行调用，内容为提供者的service接口的代码，表现形式为接口[email protected]的形式

package com.atguigu.springcloud.service;

import java.util.List;

import org.springframework.cloud.netflix.feign.FeignClient;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

import com.atguigu.springcloud.entities.Dept;


/**
 * 
 * @Description: 修改microservicecloud-api工程，根据已经有的DeptClientService接口
 * @date 2018年4月21日
 */
@FeignClient(value = "MICROSERVICECLOUD-DEPT")
public interface DeptClientService
{
	@RequestMapping(value = "/dept/get/{id}", method = RequestMethod.GET)
	public Dept get(@PathVariable("id") long id);

	@RequestMapping(value = "/dept/list", method = RequestMethod.GET)
	public List<Dept> list();

	@RequestMapping(value = "/dept/add", method = RequestMethod.POST)
	public boolean add(Dept dept);
}