SpringCloud学习笔记（五）Feign负载均衡

你的名字 2021-01-22 06:04 810阅读 0赞

项目地址：[https://github.com/gongxianshengjiadexiaohuihui/SpringCloudDemo][https_github.com_gongxianshengjiadexiaohuihui_SpringCloudDemo]

我在springCloud学习笔记三中讲了通过restTemplate+ribbon的方式，实现负载均衡，这一篇写另一种方式，Feign，Feign默认整合了ribbon,Feign只需建立一个接口，并通过注解配置，具有可插拔性

*  Feign 采用的是基于接口的注解
 *  Feign 整合了ribbon，具有负载均衡的能力
 *  整合了Hystrix，具有熔断的能力

还是在以前的项目上新建一个module

需要新导入Feign的包，

pom文件
````
    <?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">
        <modelVersion>4.0.0</modelVersion>
    
        <groupId>com.example</groupId>
        <artifactId>eureka-feign-client</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <packaging>jar</packaging>
    
        <name>eureka-feign-client</name>
        <description>Demo project for Spring Boot</description>
    
        <parent>
            <groupId>spring-cloud</groupId>
            <artifactId>eureka</artifactId>
            <version>1.0-SNAPSHOT</version>
            <relativePath/>
        </parent>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-openfeign</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <scope>test</scope>
            </dependency>
        </dependencies>
    </project>
````
配置文件
````
    eureka:
      client:
        serviceUrl:
          defaultZone: http://localhost:8761/eureka/
    server:
      port: 8765
    spring:
      application:
         name: eureka-feign-client
````
启动类
````
    package com.example.eurekafeignclient;
    
    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 EurekaFeignClientApplication {
    
        public static void main(String[] args) {
            SpringApplication.run(EurekaFeignClientApplication.class, args);
        }
    }
````
需要创建的接口
````
    package com.example.eurekafeignclient;

import org.springframework.cloud.openfeign.FeignClient;
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.RequestParam;

/**
     * @ClassName FeignClient
     * @Description TODO
     * @Author Mr.G
     * @Date 2018/9/17 18:00
     * @Version 1.0
     */
    @FeignClient(value = "eureka-client")
    public interface FeignClientDemo {
        @GetMapping("/hi")
        String FeignClientTest(@RequestParam("name") String name);
    }
````
@FeignClient是最关键的注解，里面的值是请求的服务名，接口里面的值是对应服务的映射

Controller
````
    package com.example.eurekafeignclient;

import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.*;

/**
     * @ClassName FeignController
     * @Description TODO
     * @Author Mr.G
     * @Date 2018/9/17 18:12
     * @Version 1.0
     */
    @RestController
    public class FeignController {
    
        @Autowired
        FeignClientDemo feignClientDemo;
    
        @GetMapping("/hi")
        public String Hi(@RequestParam("name") String name){
                 return feignClientDemo.FeignClientTest(name);
        }
    }
````
到此就完毕了，和以前一样的启动顺序，先启动服务，再启动两个客户端，最后启动新创建的工程

效果展示

![70][]

![70 1][]

![70 2][]

此时的工程架构图

![70 3][]

[https_github.com_gongxianshengjiadexiaohuihui_SpringCloudDemo]: https://github.com/gongxianshengjiadexiaohuihui/SpringCloudDemo
[70]: /images/1611295364769.png
[70 1]: /images/1611295382633.png
[70 2]: /images/1611295401387.png
[70 3]: /images/1611295420318.png