SpringCloudAlibaba - RPC远程调用OpenFeign

深藏阁楼爱情的钟 2023-07-01 10:56 4阅读 0赞

OpenFeign是一个Web声明式的Http客户端调用工具，提供接口和注解形式调用。开发微服务，免不了需要服务间调用。Spring Cloud框架提供了RestTemplate和FeignClient两个方式完成服务间调用，本文简要介绍如何使用OpenFeign完成服务间调用，下面开始进行整合：

首先基于IDEA建立maven聚合项目如下图：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0FraXJhTmlja3k_size_16_color_FFFFFF_t_70][]

其中，**springcloud-alibaba-parent**是父项目，存放一些共同依赖，**service-api，service-impl**是**springcloud-alibaba-parent**的module子模块，**service-api-member，service-api-order**是**service-api**的module子模块，**service-impl-member，service-impl-order**是**service-impl**的module子模块。

在**springcloud-alibaba-parent**引入如下公共依赖：

<?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>
    
        <groupId>com.xyy</groupId>
        <artifactId>springcloud-alibaba-parent</artifactId>
        <packaging>pom</packaging>
        <version>1.0-SNAPSHOT</version>
        <modules>
            <module>service-api</module>
            <module>service-impl</module>
        </modules>
    
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>2.0.0.RELEASE</version>
        </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-alibaba-nacos-discovery</artifactId>
                <version>0.2.2.RELEASE</version>
            </dependency>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-openfeign</artifactId>
                <version>2.0.0.RELEASE</version>
            </dependency>
        </dependencies>
    
    </project>

**service-impl-member**依赖如下：

<dependencies>
        <dependency>
            <groupId>com.xyy</groupId>
            <artifactId>service-api-member</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
    </dependencies>

**service-impl-order**依赖如下：

<dependencies>
        <dependency>
            <groupId>com.xyy</groupId>
            <artifactId>service-api-member</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
        <dependency>
            <groupId>com.xyy</groupId>
            <artifactId>service-api-order</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
    </dependencies>

**service-impl-member**配置文件如下：

spring:
      application:
        # 服务名称
        name: service-member
      cloud:
        nacos:
          discovery:
            # nacos注册地址
            server-addr: 127.0.0.1:8848
    server:
      port: 8081

**service-impl-order**配置文件如下：

spring:
      application:
        # 服务名称
        name: service-order
      cloud:
        nacos:
          discovery:
            # nacos注册地址
            server-addr: 127.0.0.1:8848
    server:
      port: 8090

在**service-api-member**编写Member服务：

package com.xyy;
    
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.RequestParam;
    
    public interface MemberService {
        /**
         * 提供我们发布的接口
         * @param userId
         * @return
         */
        @GetMapping("/getUser")
        String getUser(@RequestParam("userId") Integer userId);
    }

在**service-impl-member**编写实现类：

package com.xyy.impl;
    
    import com.xyy.MemberService;
    import org.springframework.beans.factory.annotation.Value;
    import org.springframework.web.bind.annotation.RestController;
    
    @RestController
    public class MemberServiceImpl implements MemberService {
        @Value("${server.port}")
        private String serverPort;
    
        @Override
        public String getUser(Integer userId) {
            return "我是会员服务" + serverPort;
        }
    }

在**service-impl-order**编写openFeign客户端（直接实现会员服务接口即可）：

package com.xyy.openfeign;
    
    import com.xyy.MemberService;
    import org.springframework.cloud.openfeign.FeignClient;
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.RequestParam;
    
    
    @FeignClient("service-member")
    public interface MemberServiceFeign extends MemberService {
    
    }

在**service-impl-order**编写订单实现：

package com.xyy.impl;
    
    import com.xyy.openfeign.MemberServiceFeign;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    @RestController
    public class OrderService {
        @Autowired
        private MemberServiceFeign memberServiceFeign;
        /**
         * 基于我们的feign客户端形式实现rpc远程调用
         * @return
         */
        @RequestMapping("/orderFeignToMember")
        public String orderFeignToMember() {
            String result = memberServiceFeign.getUser(1);
            return "我是订单服务调用会员服务的接口,返回结果" + result;
        }
    }

分别启动**service-impl-member（8080），service-impl-member（8081），service-impl-order（8090），**直接请求orderFeignToMember接口，会发现，底层默认封装了Ribbon进行客户端负载均衡：

![20200122230140292.png][]    ![20200122230204164.png][]

**【小结】：**

**·  **订单调会员的时候，会员服务接口的方法参数，一定要加@RequestParam注解，订单可以不用加。

**·  **在微服务架构中Nacos服务的名称命名不能够有下划线（service\_order是错误写法，openfeign调用的时候报错）。

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0FraXJhTmlja3k_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20200122224652562.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0FraXJhTmlja3k=,size_16,color_FFFFFF,t_70
[20200122230140292.png]: https://img-blog.csdnimg.cn/20200122230140292.png
[20200122230204164.png]: https://img-blog.csdnimg.cn/20200122230204164.png