java版b2b2c社交电商spring cloud分布式微服务（三）服务消费者（Feign）

╰半橙微兮° 2022-10-01 11:57 4阅读 0赞

### 一、Feign简介 ###

电子商务社交平台源码请加企鹅求求：一零三八七七四六二六。Feign是一个声明式的伪Http客户端，它使得写Http客户端变得更简单。使用Feign，只需要创建一个接口并注解。它具有可插拔的注解特性，可使用Feign 注解和JAX-RS注解。Feign支持可插拔的编码器和解码器。Feign默认集成了Ribbon，并和Eureka结合，默认实现了负载均衡的效果。

简而言之：

*  Feign 采用的是基于接口的注解
 *  Feign 整合了ribbon
 *

### 二、准备工作 ###

继续用上一节的工程， 启动eureka-server，端口为8761; 启动service-hi 两次，端口分别为8762 、8773.

### 三、创建一个feign的服务 ###

新建一个spring-boot工程，取名为serice-feign，在它的pom文件引入Feign的起步依赖spring-cloud-starter-feign、Eureka的起步依赖spring-cloud-starter-eureka、Web的起步依赖spring-boot-starter-web，代码如下：

<?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.forezp</groupId>
        <artifactId>service-feign</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <packaging>jar</packaging>
        <name>service-feign</name>
        <description>Demo project for Spring Boot</description>
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>1.5.2.RELEASE</version>
            <relativePath/> 
        </parent>
     
        <properties>
            <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
            <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
            <java.version>1.8</java.version>
        </properties>
     
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-eureka</artifactId>
            </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.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <scope>test</scope>
            </dependency>
        </dependencies>
        <dependencyManagement>
            <dependencies>
                <dependency>
                    <groupId>org.springframework.cloud</groupId>
                    <artifactId>spring-cloud-dependencies</artifactId>
                    <version>Dalston.RC1</version>
                    <type>pom</type>
                    <scope>import</scope>
                </dependency>
            </dependencies>
        </dependencyManagement>
        <build>
            <plugins>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                </plugin>
            </plugins>
        </build>
     
        <repositories>
            <repository>
                <id>spring-milestones</id>
                <name>Spring Milestones</name>
                <url>https://repo.spring.io/milestone</url>
                <snapshots>
                    <enabled>false</enabled>
                </snapshots>
            </repository>
        </repositories>
    </project>复制代码

在工程的配置文件application.yml文件，指定程序名为service-feign，端口号为8765，服务注册地址为[http://localhost:8761/eureka/][http_localhost_8761_eureka] ，代码如下：

eureka:
      client:
        serviceUrl:
          defaultZone: http://localhost:8761/eureka/
    server:
      port: 8765
    spring:
      application:
        name: service-feign复制代码

在程序的启动类ServiceFeignApplication ，加上@EnableFeignClients注解开启Feign的功能：

@SpringBootApplication
    @EnableDiscoveryClient
    @EnableFeignClients
    public class ServiceFeignApplication {
     
        public static void main(String[] args) {
            SpringApplication.run(ServiceFeignApplication.class, args);
        }
    }复制代码

定义一个feign接口，通过@ FeignClient（“服务名”），来指定调用哪个服务。比如在代码中调用了service-hi服务的“/hi”接口，代码如下：

<br>/**
     * Created by fangzhipeng on 2017/4/6.
     */
    @FeignClient(value = "service-hi")
    public interface SchedualServiceHi {
        @RequestMapping(value = "/hi",method = RequestMethod.GET)
        String sayHiFromClientOne(@RequestParam(value = "name") String name);
    }<br>复制代码

在Web层的controller层，对外暴露一个”/hi”的API接口，通过上面定义的Feign客户端SchedualServiceHi 来消费服务。代码如下：

@RestController
    public class HiController {
     
        @Autowired
        SchedualServiceHi schedualServiceHi;
        @RequestMapping(value = "/hi",method = RequestMethod.GET)
        public String sayHi(@RequestParam String name){
            return schedualServiceHi.sayHiFromClientOne(name);
        }
    }复制代码

启动程序，多次访问[http://localhost:8765/hi?name=forezp][http_localhost_8765_hi_name_forezp],浏览器交替显示：

hi forezp,i am from port:8762
     
    hi forezp,i am from port:8763复制代码

需要JAVASpring Cloud大型企业分布式微服务云构建的B2B2C电子商务社交平台源码请加企鹅求求：一零三八七七四六二六

转载于:https://juejin.im/post/5ce3becfe51d454f71439c2d

[http_localhost_8761_eureka]: https://link.juejin.im?target=http%3A%2F%2Flocalhost%3A8761%2Feureka%2F
[http_localhost_8765_hi_name_forezp]: https://link.juejin.im?target=http%3A%2F%2Flocalhost%3A8765%2Fhi%3Fname%3Dforezp