SpringCloud学习系列-Feign负载均衡

Posted 2021-03-20 XiangHuiBlog

Feign使用步骤

1.参考microservicecloud-consumer-dept-80   新建microservicecloud-consumer-dept-feign

  修改主启动类名字DeptConsumer80_Feign_App

2.microservicecloud-consumer-dept-feign工程pom.xml修改，主要添加对feign的支持

<dependency>
       <groupId>org.springframework.cloud</groupId>
       <artifactId>spring-cloud-starter-feign</artifactId>
   </dependency>

3.修改microservicecloud-api工程

POM

<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><!-- 子类里面显示声明才能有明确的继承表现，无意外就是父类的默认版本否则自己定义 -->
   <groupId>com.atguigu.springcloud</groupId>
   <artifactId>microservicecloud</artifactId>
   <version>0.0.1-SNAPSHOT</version>
  </parent>
 
  <artifactId>microservicecloud-api</artifactId><!-- 当前Module我自己叫什么名字 -->
 
  <dependencies><!-- 当前Module需要用到的jar包，按自己需求添加，如果父类已经包含了，可以不用写版本号 -->
   <dependency>
     <groupId>org.projectlombok</groupId>
     <artifactId>lombok</artifactId>
   </dependency>
   <dependency>
     <groupId>org.springframework.cloud</groupId>
     <artifactId>spring-cloud-starter-feign</artifactId>
   </dependency>
  </dependencies>
 
 
 
</project>

新建DeptClientService接口并新增注解@FeignClient

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;
 
@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);
}
 

mvn clean

mvn install

4.microservicecloud-consumer-dept-feign工程修改Controller，添加上一步新建的DeptClientService接口

package com.atguigu.springcloud.controller;
 
import java.util.List;
 
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
 
import com.atguigu.springcloud.entities.Dept;
import com.atguigu.springcloud.service.DeptClientService;
 
@RestController
public class DeptController_Feign
{
  @Autowired
  private DeptClientService service = null;
 
  @RequestMapping(value = "/consumer/dept/get/{id}")
  public Dept get(@PathVariable("id") Long id)
  {
   return this.service.get(id);
  }
 
  @RequestMapping(value = "/consumer/dept/list")
  public List<Dept> list()
  {
   return this.service.list();
  }
 
  @RequestMapping(value = "/consumer/dept/add")
  public Object add(Dept dept)
  {
   return this.service.add(dept);
  }
}
 

5.microservicecloud-consumer-dept-feign工程修改主启动类

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;
 
 
@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);
  }
}
 
 

6.测试

启动3个eureka集群

启动3个部门微服务8001/8002/8003

启动Feign自己启动

http://localhost/consumer/dept/list

Feign自带负载均衡配置项

7.小结

Feign通过接口的方法调用Rest服务（之前是Ribbon+RestTemplate），
该请求发送给Eureka服务器（http://MICROSERVICECLOUD-DEPT/dept/list）,
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作用。