使用Feign负载均衡

素颜马尾好姑娘i 2023-10-11 10:19 60阅读 0赞

Feign 也是在客户端的负载均衡。其也集成了Ribbon负债均衡，它与Ribbon不同的是通过肺功能只要定义

服务绑定接口且以声明式的方法，优雅而简单的实现了服务的调用。

下面介绍使用步骤：

1.建立一个客户端消费者module。

pom文件内容：

<?xml version="1.0" encoding="UTF-8"?>
    <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">
        <parent>
            <artifactId>microservicecloud</artifactId>
            <groupId>com.atguigu.springcloud</groupId>
            <version>0.0.1-SNAPSHOT</version>
        </parent>
        <modelVersion>4.0.0</modelVersion>
    
        <artifactId>microservicecloud-consumer-dept-feign</artifactId>
        <dependencies>
            <dependency>
                <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>
    
            <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-ribbon</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-config</artifactId>
            </dependency>
            
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>springloaded</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-devtools</artifactId>
            </dependency>
        </dependencies>
    
    </project>

2.配置yaml：

server:
      port: 8000
    feign:
      hystrix:
        enabled: true
    
    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.编写controller：

package com.atguigu.springcloud.controller;
    
    import com.atguigu.springcloud.entities.Dept;
    import com.atguigu.springcloud.service.DeptClientService;
    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 org.springframework.web.client.RestTemplate;
    
    import java.util.List;
    
    /**
     * 使用restTemplate访问restful接口非常的简单粗暴无脑。
     * (url, requestMap, ResponseBean.class)这三个参数分别代表
     * REST请求地址、请求参数、HTTP响应转换被转换成的对象类型。
     */
    @RestController
    public class DeptController_Consumer {
        @Autowired
        private DeptClientService service = null;//这个接口待会会在api工程里建立！
    
        @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);
        }
    }

4.主启动类：

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

5.修改api工程：

在pom文件中添加feign的依赖：

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

新建立DeptClientService接口，并且添加注解：

@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);
    }

这样就完事了，完整工程地址：[https://hn.devcloud.huaweicloud.com/codehub/project/db863c4dd09b44e1949853aa22197df3/codehub/7172321/home][https_hn.devcloud.huaweicloud.com_codehub_project_db863c4dd09b44e1949853aa22197df3_codehub_7172321_home]

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。

[https_hn.devcloud.huaweicloud.com_codehub_project_db863c4dd09b44e1949853aa22197df3_codehub_7172321_home]: https://hn.devcloud.huaweicloud.com/codehub/project/db863c4dd09b44e1949853aa22197df3/codehub/7172321/home