Spring Cloud 之 Feign

系统管理员 2023-07-18 09:11 15阅读 0赞

关于Feign是什么的问题可以参考以下：

[https://www.jianshu.com/p/94177e224ef8][https_www.jianshu.com_p_94177e224ef8]

[https://www.cnblogs.com/756623607-zhang/p/8661571.html][https_www.cnblogs.com_756623607-zhang_p_8661571.html]

后边介绍Fein中有依赖Eureka和Ribbon可以看这些博客

[ Spring Cloud之Eureka][Spring Cloud_Eureka]

[Spring Cloud之Ribbon实现负载均衡][Spring Cloud_Ribbon]

1.版本：

SpringBoot：2.2.5.RELEASE  
Spring Cloud：Hoxton.SR1

2.项目结构

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0hlbGxvV29ybGRZYW5nU29uZw_size_16_color_FFFFFF_t_70][]

共4个服务：feign-web-api、feign-service-a、feign-service-b、feign-service-c

3.parent依赖

<?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>
      <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.5.RELEASE</version>
        <relativePath/>
      </parent>
      <groupId>com.yarm</groupId>
      <artifactId>feign</artifactId>
        <packaging>pom</packaging>
        <version>1.0-SNAPSHOT</version>
        <modules>
          <module>service-a</module>
          <module>service-b</module>
          <module>service-c</module>
          <module>web-api</module>
        </modules>
    
      <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.boot</groupId>
          <artifactId>spring-boot-starter</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>
    
        <dependency>
          <groupId>org.springframework.boot</groupId>
          <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
      </dependencies>
    
      <dependencyManagement>
        <dependencies>
          <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-dependencies</artifactId>
            <version>Hoxton.SR1</version>
            <type>pom</type>
            <scope>import</scope>
          </dependency>
        </dependencies>
      </dependencyManagement>
    </project>

3.其余模块依赖类似、如下：

4. 启动函数

@SpringBootApplication
    @EnableFeignClients
    @EnableEurekaClient
    public class WebApiApplication {
        public static void main(String[] args) {
            SpringApplication.run(WebApiApplication.class, args);
        }
    }

说明：

@EnableFeignClients  // 表示feign客户端

5.配置文件，几个服务都类似

server.port=7000
    spring.application.name=feign-web-api
    eureka.client.serviceUrl.defaultZone=http://localhost:8761/eureka/
    # 开启健康检查
    eureka.client.healthcheck.enabled=true
    # eureka client发送心跳给server端的频率。如果在leaseExpirationDurationInSeconds后，server端没有收到client的心跳，则将摘除该instance
    eureka.instance.lease-renewal-interval-in-seconds=3
    # eureka server至上一次收到client的心跳之后，等待下一次心跳的超时时间，在这个时间内若没收到下一次心跳，则将移除该instance
    eureka.instance.lease-expiration-duration-in-seconds=6

6.服务调用链

feign-web-api-->feign-service-a-->feign-service-b-->feign-service-c

7. 以feign-web-api调用feign-service-a举例

7.1 feign-service-a服务提供服务，和springmvc方式一样，加controller：

package com.yarm.controller;
    
    import com.yarm.service.FeignServiceB;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    @RequestMapping
    @RestController
    public class OpneController {
        @Autowired
        FeignServiceB feignServiceB;
        /**
         * @Description :对外提供服务接口
         * @Author : yarm.yang
         * @Date : 2020/3/25 14:19
         * @Return :
        */
        @RequestMapping("toA")
        public String open(){
            String result = "feign-service-a";
            String s = feignServiceB.toB();
            return result + "-->" + s;
        }
    }

7.2 feign-web-api作为消费者需新建接口，加上注解@FeignClient("feign-service-a")，其中feign-service-a表示要调用的服务。

package com.yarm.service;
    
    import org.springframework.cloud.openfeign.FeignClient;
    import org.springframework.web.bind.annotation.RequestMapping;
    
    /**
     * @Description :调用服务feign-service-a
     * @Author : yarm.yang
     * @Date : 2020/3/25 14:15
    */
    @FeignClient("feign-service-a")
    public interface FeignServiceA {
        @RequestMapping("toA")
        String  toA();
    }

7.3 注入FeignServiceA接口就可以直接调用feign-service-a的接口了

package com.yarm.controller;
    
    import com.yarm.service.FeignServiceA;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    @RestController
    @RequestMapping("api")
    public class ConsumerController {
    
        @Autowired
        FeignServiceA feignServiceA;
    
        @RequestMapping("getLink")
        public String get(){
            String result = "feign-web-api";
            // 调用服务feign-service-a
            String s = feignServiceA.toA();
            return result + "-->" + s;
        }
    }

其他的服务类似，调用feign-web-api接口

[http://127.0.0.1:7000/api/getLink][http_127.0.0.1_7000_api_getLink]

输出：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0hlbGxvV29ybGRZYW5nU29uZw_size_16_color_FFFFFF_t_70 1][]

8.代码地址

[https://github.com/15902124763/spring-cloud][https_github.com_15902124763_spring-cloud]

[https_www.jianshu.com_p_94177e224ef8]: https://www.jianshu.com/p/94177e224ef8
[https_www.cnblogs.com_756623607-zhang_p_8661571.html]: https://www.cnblogs.com/756623607-zhang/p/8661571.html
[Spring Cloud_Eureka]: https://blog.csdn.net/HelloWorldYangSong/article/details/104680591
[Spring Cloud_Ribbon]: https://blog.csdn.net/HelloWorldYangSong/article/details/104791259
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0hlbGxvV29ybGRZYW5nU29uZw_size_16_color_FFFFFF_t_70]: /images/20230528/713eb34fd4064e30a966eee066b1a149.png
[http_127.0.0.1_7000_api_getLink]: http://127.0.0.1:7000/api/getLink
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0hlbGxvV29ybGRZYW5nU29uZw_size_16_color_FFFFFF_t_70 1]: /images/20230528/c6444d967cc94b1a9129e98f430442e3.png
[https_github.com_15902124763_spring-cloud]: https://github.com/15902124763/spring-cloud