8、服务发现&服务消费者Feign

2024-12-10 技术教程

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>  <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-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

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@EnableFeignClientspublic 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: 5800application.ymlspring: application: name: sc-eureka-client-consumer-feigneureka: 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

方法二

7、使用postman验证
查询：
http://127.0.0.1:5800/feign/user/getUser/4

列表：
http://127.0.0.1:5800/feign/user/listUser

添加：
http://127.0.0.1:5800/feign/user/addUser

更新：
http://127.0.0.1:5800/feign/user/updateUser

删除：
http://127.0.0.1:5800/feign/user/deleteUser/6

备注：
sc-eureka-client-provider项目的UserController.java 需要修正

https://gitee.com/hjj520/spring-cloud-2.x/tree/master/sc-eureka-client-consumer-feign